130 FERC ¶ 61,221 

UNITED STATES OF AMERICA 

FEDERAL ENERGY REGULATORY COMMISSION 

18 CFR Part 40 

[Docket No. RM08-13-000; Order No. 733] 

Transmission Relay Loadability Reliability Standard 

(Issued March 18, 2010) 

AGENCY: Federal Energy Regulatory Commission. 

ACTION: Final Rule. 

SUMMARY: Pursuant to section 215 of the Federal Power Act, the Federal Energy 

Regulatory Commission approves the Transmission Relay Loadability Reliability 

Standard (PRC-023-1), developed by the North American Electric Reliability 

Corporation (NERC). Reliability Standard PRC-023-1 requires transmission owners, 

generator owners, and distribution providers to set load-responsive phase protection 

relays according to specific criteria in order to ensure that the relays reliably detect and 

protect the electric network from all fault conditions, but do not limit transmission 

loadability or interfere with system operators’ ability to protect system reliability. In 

addition, pursuant to section 215(d)(5) of the Federal Power Act, the Commission directs 

NERC to develop modifications to the Reliability Standard to address specific concerns 

identified by the Commission. 

EFFECTIVE DATE: This rule will become effective [Insert Date that is 45 days after 

publication in the FEDERAL REGISTER]. 
Docket No. RM08-13-000 - 2 - 

FOR FURTHER INFORMATION CONTACT: 

Cynthia Pointer (Technical Information) 

Office of Electric Reliability 

Division of Reliability Standards 

Federal Energy Regulatory Commission 

888 First Street, NE 

Washington, DC 20426 

(202) 502-6069 

Joshua Konecni (Legal Information) 

Office of the General Counsel 

Federal Energy Regulatory Commission 

888 First Street, NE 

Washington, DC 20426 

(202) 502-6291 

SUPPLEMENTARY INFORMATION:
UNITED STATES OF AMERICA 

FEDERAL ENERGY REGULATORY COMMISSION 

Transmission Relay Loadability Reliability Standard Docket No. RM08-13-000 

ORDER NO. 733 

TABLE OF CONTENTS

 Paragraph Numbers

I. Background ............................................................................................................................2.

II. Reliability Standard PRC-023-1 ............................................................................................5.

 A. Applicability ....................................................................................................................6.

 B. Requirements ....................................................................................................................8.

 1. Requirement R1...........................................................................................................9.

 2. Requirement R2...........................................................................................................10.

 3. Requirement R3...........................................................................................................11.

III. Discussion.............................................................................................................................12.

 A. Overview.........................................................................................................................12.

 B. Approval of PRC-023-1..................................................................................................13.

 C. Applicability ..................................................................................................................20.

 D. Generator Step-Up and Auxiliary Transformers ...........................................................98.

 1. Omission from the Reliability Standard ....................................................................98.

 2. Generator Step-Up Transformer Relays as Back-up Protection ................................109.

 E. Need to Address Additional Issues .................................................................................115.

1. Zone 3/Zone 2 Relays Applied as Remote Circuit Breaker Failure and Backup 

Protection ........................................................................................................................116.

 2. Protective Relays Operating Unnecessarily due to Stable Power Swings ................130.

 F. Requirement R1...............................................................................................................174.

 1. Sub-Requirement R1.1 ...............................................................................................175.

 2. Sub-Requirement R1.2 ...............................................................................................178.

 3. Sub-Requirement R1.10 .............................................................................................190.

 4. Sub-Requirement R1.12 .............................................................................................213.

 G. Requirement R2..............................................................................................................227.

 H. Requirement R3 and its Sub-Requirements ...................................................................230.

 1. Role of the Planning Coordinator .............................................................................231.

 2. Sub-Requirement R3.3 .............................................................................................235.
Docket No. RM08-13-000 ii 

 I. Attachment A ................................................................................................................238.

 1. Section 2: Evaluation of Out-of-Step Blocking Schemes ........................................239.

 2. Section 3: Protection Systems Excluded from the Reliability Standard ..................249.

 J. Effective Date ...............................................................................................................273.

 K. Violation Risk Factors ...................................................................................................285.

 L. Violation Severity Levels..............................................................................................298.

 M. Miscellaneous ...............................................................................................................313.

 1. Purpose of the Reliability Standard........................................................................313.

 2. Transmission Facility Design Margin ....................................................................316.

IV. Information Collection Statement .......................................................................................318.

V. Environmental Analysis .......................................................................................................329.

VI. Regulatory Flexibility Act....................................................................................................330.

VII. Document Availability........................................................................................................345.

VIII. Effective Date and Congressional Notification.................................................................348.
 

130 FERC ¶ 61,221 

UNITED STATES OF AMERICA 

FEDERAL ENERGY REGULATORY COMMISSION 

Before Commissioners: Jon Wellinghoff, Chairman; 

 Marc Spitzer, Philip D. Moeller, 

 and John R. Norris. 

Transmission Relay Loadability Reliability Standard Docket No. RM08-13-000 

ORDER NO. 733 

FINAL RULE 

(Issued March 18, 2010) 

1. Pursuant to section 215 of the Federal Power Act (FPA),1

 the Commission 

approves the Transmission Relay Loadability Reliability Standard (PRC-023-1), 

developed by the North American Electric Reliability Corporation (NERC) in its capacity 

as the Electric Reliability Organization (ERO).2

 Reliability Standard PRC-023-1 requires 

transmission owners, generator owners, and distribution providers to set load-responsive 

1

 16 U.S.C. 824o. The Commission is not adding any new or modified text to its 

regulations. 

2

 Section 215(e)(3) of the FPA directs the Commission to certify an ERO to 

develop mandatory and enforceable Reliability Standards, subject to Commission review 

and approval. 16 U.S.C. 824o(e)(3). Following a selection process, the Commission 

selected and certified NERC as the ERO. North American Electric Reliability Corp., 

116 FERC ¶ 61,062 (ERO Certification Order), order on reh’g & compliance, 117 FERC 

¶ 61,126 (ERO Rehearing Order) (2006), aff’d sub nom. Alcoa, Inc. v. FERC, 564 F.3d 

1342 (D.C. Cir. 2009). 
Docket No. RM08-13-000 - 2 - 

phase protection relays according to specific criteria in order to ensure that the relays 

reliably detect and protect the electric network from all fault conditions, but do not limit 

transmission loadability or interfere with system operators’ ability to protect system 

reliability.3

 In addition, pursuant to section 215(d)(5) of the FPA,4 the Commission 

directs the ERO to develop modifications to PRC-023-1 to address specific concerns 

identified by the Commission and sets specific deadlines for these modifications. 

I. Background

2. Protective relays are devices that detect and initiate the removal of faults on an 

electric system.5

 They are designed to read electrical measurements, such as current, 

voltage, and frequency, and can be set to recognize certain measurements as indicating a 

fault. When a protective relay detects a fault on an element of the system under its 

protection, it sends a signal to an interrupting device(s) (such as a circuit breaker) to 

disconnect the element from the rest of the system.6

 Impedance relays (also known as 

 3

 Loadability refers to the ability of protective relays to refrain from operating 

under load conditions. 

4

 16 U.S.C. 824o(d)(5). 

5

 Protective relays are one type of equipment used in protection systems. The 

NERC definition of protection systems also includes communication systems associated 

with protective relays, voltage and current sensing devices, station batteries, and DC 

control circuitry. See NERC Glossary of Terms Used in Reliability Standards at 14. 

6

 Coordination of protection through distance settings and time delays ensures that 

the relay closest to a fault operates before a relay farther away from the fault, thereby 

(continued...) 
Docket No. RM08-13-000 - 3 - 

 

distance relays) are the most common type of load-responsive phase protection relays 

used to protect transmission lines. Impedance relays can also provide backup protection 

and protection against remote circuit breaker failure. 

3. Following the August 2003 blackout that affected parts of the Midwest and 

Northeast United States, and Ontario, Canada, NERC and the U.S.-Canada Power System 

Outage Task Force (Task Force) concluded that a substantial number of transmission 

lines disconnected during the blackout when load-responsive phase-protection backup 

distance and phase relays operated unnecessarily, i.e. under non-fault conditions. 

Although these relays operated according to their settings, the Task Force determined that 

the operation of these relays for non-fault conditions contributed to cascading outages at 

the start of the blackout and accelerated the geographic spread of the cascade.7

 

4. Seeking to prevent or minimize the scope of future blackouts, both NERC and the 

Task Force made recommendations to ensure that these types of protective relays do not 

contribute to future blackouts. Recommendation 8A of the NERC Report addresses the 

ensuring that the more distant relay does not disconnect both the transmission equipment 

necessary to remove the fault and “healthy” equipment that should remain in service. 

7

 U.S.-Canada Power System Outage Task Force, Final Report on the August 14, 

2003 Blackout in the United States and Canada: Causes and Recommendations, at 80 

(2004) (Final Blackout Report). 
Docket No. RM08-13-000 - 4 - 

 

need to evaluate load-responsive protection zone 3 relays8

 to determine whether they will 

operate under extreme emergency conditions: 

All transmission owners shall, no later than September 30, 2004, evaluate 

the zone 3 relay settings on all transmission lines operating at 230 kV and 

above for the purpose of verifying that each zone 3 relay is not set to trip on 

load under extreme emergency conditions[]. In each case that a zone 3 

relay is set so as to trip on load under extreme conditions, the transmission 

operator shall reset, upgrade, replace, or otherwise mitigate the overreach of 

those relays as soon as possible and on a priority basis, but no later than 

December 31, 2005. Upon completing analysis of its application of zone 3 

relays, each transmission owner may no later than December 31, 2004 

submit justification to NERC for applying zone 3 relays outside of these 

recommended parameters. The Planning Committee shall review such 

exceptions to ensure they do not increase the risk of widening a cascading 

failure of the power system.9

 

Recommendation No. 21A of the Task Force Final Blackout Report (Final Blackout 

Report) urges NERC to expand the scope of its review to include certain operationally 

significant facilities: 

NERC [should] broaden the review [described in Recommendation 8A of 

the NERC Report] to include operationally significant 115 kV and 138 kV 

lines, e.g., lines that are part of monitored flowgates or interfaces. 

8

 Multiple impedance relays are installed at each end of a transmission line, with 

each used to protect a certain percentage, or zone, of the local transmission line and 

remote lines. Zone 3 relays and zone 2 relays set to operate like zone 3 relays (zone 

3/zone 2 relays) are typically set to reach 100 percent of the protected transmission line 

and more than 100 percent of the longest line (including any series elements such as 

transformers) that emanates from the remote buses. 

9

 August 14, 2003 Blackout: NERC Actions to Prevent and Mitigate the Impacts 

of Future Cascading Blackouts, at 13 (2004) (NERC Report). 
Docket No. RM08-13-000 - 5 - 

Transmission owners should also look for zone 2 relays set to operate like 

zone 3 [relays].10

In its petition, NERC states that PRC-023-1 is intended to specifically address these 

recommendations. 

II. Reliability Standard PRC-023-1

5. Reliability Standard PRC-023-1 requires transmission owners, generator owners, 

and distribution providers to set load-responsive phase protection relays according to 

specific criteria in order to ensure that the relays reliably detect and protect the electric 

network from all fault conditions, but do not operate during non-fault load conditions. 

A. Applicability 

6. As proposed by NERC, the Reliability Standard applies to relay settings on: 

(1) all transmission lines and transformers with low-voltage terminals operated or 

connected at or above 200 kV;11 and (2) those transmission lines and transformers with 

 10 Final Blackout Report at 158. 

11 NERC explains in general that it decided to make PRC-023-1 voltage-levelspecific because the definition of what is included in the “bulk electric system” varies 

throughout the eight Regional Entities and because the effects of PRC-023-1 are not 

constrained to regional boundaries. For example, if one Region has purely performancebased criteria and an adjoining Region has voltage-based criteria, these criteria may not 

permit consideration of the effects of protective relay operation in one Region upon the 

behavior of facilities in the adjoining Region. NERC Petition at 18-19, 39-41. 
Docket No. RM08-13-000 - 6 - 

 

low-voltage terminals operated or connected between 100 kV and 200 kV12 that are 

designated by planning coordinators as critical to the reliability of the bulk electric 

system.13 

7. Attachment A to the Reliability Standard specifies which protection systems are 

subject to and excluded from the Standard’s Requirements. Section 1 of Attachment A 

provides that the Reliability Standard applies to any protective functions that can operate 

with or without time delay, on load current, including but not limited to: (1) phase 

distance; (2) out-of-step tripping; (3) switch-on-to-fault; (4) overcurrent relays; and 

12 In this Final Rule, we occasionally use the shorthand “100 kV-200 kV facilities” 

to refer to transmission lines and transformers with low-voltage terminals operated or 

connected between 100 kV and 200 kV. 

13 In this Final Rule, we use the terms “bulk electric system” and “Bulk-Power 

System.” “Bulk electric system” is defined in the NERC Glossary of Terms Used in 

Reliability Standards, and generally includes facilities operated at voltages at and above 

100 kV. See NERC Glossary of Terms Used in Reliability Standards at 2. “Bulk-Power 

System” is defined in section 215 of the FPA, and does not include a voltage threshold. 

See 16 U.S.C. 824o(a)(1). In Order No. 693, the Commission explained that while it 

would rely on the NERC definition of bulk electric system during the start-up phase of 

the mandatory Reliability Standard regime, the statutory Bulk-Power System 

encompasses more facilities than are included in NERC’s definition of the bulk electric 

system. Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, 

FERC Stats. & Regs. ¶ 31,242, at P 75-76; order on reh’g, Order No. 693-A, 120 FERC 

¶ 61,053 (2007). 
Docket No. RM08-13-000 - 7 - 

 

(5) communication-aided protection applications.14 Section 2 states that the Reliability 

Standard requires evaluation of out-of-step blocking schemes15 to ensure that they do not 

operate for faults during the loading conditions defined in the Standard’s Requirements. 

Finally, section 3 expressly excludes from the Reliability Standard’s Requirements: 

(1) relay elements enabled only when other relays or associated systems fail (e.g., 

overcurrent elements enabled only during abnormal system conditions or a loss of 

communications); (2) protection relay systems intended for the detection of ground fault 

conditions or for protection during stable power swings; (3) generator protection relays 

susceptible to load; (4) relay elements used only for special protection systems applied 

and approved in accordance with Reliability Standards PRC-012 through PRC-017;16 

(5) protection relay systems designed to respond only in time periods that allow operators 

15 minutes or longer to respond to overload conditions; (6) thermal emulation relays used 

14 Section 1.5 specifies that the communications aided applications subject to the 

Reliability Standard include, but are not limited to: (1) permissive overreach transfer 

trip; (2) permissive under-reach transfer trip; (3) directional comparison blocking; and 

(4) directional comparison unblocking. 

15 “Out-of-step blocking” refers to a protection system that is capable 

distinguishing between a fault and a power swing. If a power swing is detected, the 

protection system, “blocks,” or prevents the tripping of its associated transmission 

facilities. 

16 The Commission has not yet acted on PRC-012-0, PRC-013-0, or PRC-014-0 

because it is awaiting further information from the ERO. 
Docket No. RM08-13-000 - 8 - 

in conjunction with dynamic facility ratings; (7) relay elements associated with DC line; 

and (8) relay elements associated with DC converter transformers. 

B. Requirements

8. Reliability Standard PRC-023-1 consists of three Requirements. Requirement R1 

directs entities to set their relays according to one of the options set forth in subrequirements R1.1 through R1.13. Requirement R2 contains directives for entities that 

set their relays according to sub-requirements R1.6 through R1.9, R1.12, or R1.13. 

Requirement R3 directs planning coordinators to designate which facilities operated 

between 100 kV and 200 kV are critical to the reliability of the bulk electric system and 

therefore must have their relays set according to one of the options in Requirement R1. 

1. Requirement R1

9. Requirement R1 directs entities to set their relays according to one of thirteen 

specific settings (sub-requirements R1.1 through R1.13) intended to maximize loadability 

while maintaining Reliable Operation of the bulk electric system for all fault conditions. 

Entities must evaluate relay loadability at 0.85 per unit voltage and a power factor angle 

of 30 degrees and set their transmission line relays so that they do not operate: 

R1.1. [A]t or below 150 [percent] of the highest seasonal [f]acility [r]ating 

of a circuit, for the available defined loading duration nearest 4 hours 

(expressed in amperes)[;] 
Docket No. RM08-13-000 - 9 - 

 

R1.2. [A]t or below 115 [percent] of the highest seasonal 15-minute 

[f]acility [r]ating[] of a circuit (expressed in amperes)[;]17

R1.3. [A]t or below 115 [percent] of the maximum theoretical power 

transfer capability (using a 90-degree angle between the sending-end and 

receiving-end voltages and either reactance or complex impedance) of the 

circuit (expressed in amperes) using one of the following to perform the 

power transfer calculation: 

R1.3.1. An infinite source (zero source impedance) with a 1.00 per 

unit bus voltage at each end of the line[;] [or] 

R1.3.2. An impedance at each end of the line, which reflects the 

actual system source impedance with a 1.05 per unit voltage behind 

each source impedance[;] 

R1.4. [O]n series compensated transmission lines[,] . . . at or below the 

maximum power transfer capability of the line, determined as the greater 

of: 

[a.] 115 [percent] of the highest emergency rating of the series 

capacitor[;] [or] 

[b.] 115 [percent] of the maximum power transfer capability of the 

circuit (expressed in amperes), calculated in accordance with R1.3, 

using the full line inductive reactance[;] 

R1.5. [O]n weak source systems[,] . . . at or below 170 [percent] of the 

maximum end-of-line three-phase fault magnitude (expressed in 

amperes)[;] 

R1.6. [On] transmission line relays applied on transmission lines connected 

to generation stations remote to load[,] . . . at or below 230 [percent] of the 

aggregated generation nameplate capability[;] 

17 NERC includes a footnote that states “[w]hen a 15-minute rating has been 

calculated and published for use in real-time operations, the 15-minute rating can be used 

to establish the loadability requirement for the protective relays.” 
Docket No. RM08-13-000 - 10 - 

R1.7. [On] transmission line relays applied at the load center terminal, 

remote from generation stations, . . . at or below 115 [percent] of the 

maximum current flow from the load to the generation source under any 

system configuration[;] 

R1.8. [On] transmission line relays applied on the bulk system-end of 

transmission lines that serve load remote to the system[,] . . . at or below 

115 [percent] of the maximum current flow from the system to the load 

under any system configuration[;] 

R1.9. [On] transmission line relays applied on the load-end of transmission 

lines that serve load remote to the bulk system[,] . . . at or below 115 

[percent] of the maximum current flow from the load to the system under 

any system configuration[;] 

R1.10. [On] transformer fault protection relays and transmission line relays 

on transmission lines terminated only with a transformer[,] . . . at or below 

the greater of: 

[a.] 150 [percent] of the applicable maximum transformer nameplate 

rating (expressed in amperes), including the forced cooled ratings 

corresponding to all installed supplemental cooling equipment[;] [or] 

[b.] 115 [percent] of the highest operator established emergency 

transformer rating[;] 

R1.11. For transformer overload protection relays that do not comply with 

R1.10[,] [the entity must either]. . . . 

[a.] Set the relays to allow the transformer to be operated at an 

overload level of at least 150 [percent] of the maximum applicable 

nameplate rating, or 115 [percent] of the highest operator established 

emergency transformer rating, whichever is greater. The protection 

must allow this overload for at least 15 minutes to allow for the 

operator to take controlled action to relieve the overload[;] [or] 

[b.] Install supervision for the relays using either a top oil or 

simulated winding hot spot temperature element. The setting should 
Docket No. RM08-13-000 - 11 - 

be no less than 100° C for the top oil or 140° C for the winding hot 

spot temperature[][;]18

R1.12. When the desired transmission line capability is limited by the 

requirement to adequately protect the transmission line, set the transmission 

line distance relays to a maximum of 125 [percent] of the apparent 

impedance (at the impedance angle of the transmission line) subject to the 

following constraints: 

R1.12.1. Set the maximum torque angle (MTA) to 90 degrees or the 

highest supported by the manufacturer[;] 

 

R1.12.2. Evaluate the relay loadability in amperes at the relay trip 

point at 0.85 per unit voltage and a power factor angle of 30 

degrees[;] [and] 

R1.12.3. Include a relay setting component of 87 [percent] of the 

current calculated in R1.12.2 in the [f]acility [r]ating determination 

for the circuit[;] 

R1.13. [Finally,] [w]here other situations present practical 

limitations on circuit capability, [entities can] set the phase 

protection relays so they do not operate at or below 115 [percent] of 

such limitations. 

2. Requirement R2

10. Requirement R2 provides that entities that set their relays according to subrequirements R1.6 through R1.9, R1.12, or R1.13 must use the calculated circuit 

capability as the circuit’s facility rating and must obtain the agreement of the planning 

 18 NERC includes a footnote that states: “IEEE [S]tandard C57.115, Table 3, 

specifies that transformers are to be designed to withstand a winding hot spot temperature 

of 180 degrees C, and cautions that bubble formation may occur above 140 degrees C.” 
Docket No. RM08-13-000 - 12 - 

coordinator, transmission operator, and reliability coordinator with authority over the 

facility as to the calculated circuit capability. 

3. Requirement R3

11. Requirement R3 directs planning coordinators to designate which facilities 

operated between 100 kV and 200 kV are critical to the reliability of the bulk electric 

system and therefore must have their relays set according to one of the options in 

Requirement R1. Sub-requirement R3.1 requires planning coordinators to have a process 

to identify critical facilities. Sub-requirement R3.1.1 specifies that the process must 

consider input from adjoining planning coordinators and affected reliability coordinators. 

Sub-requirements R3.2 and R3.3 require planning coordinators to maintain a list of 

critical facilities and provide it to reliability coordinators, transmission owners, generator 

owners, and distribution providers within 30 days of initially establishing it, and 30 days 

of any subsequent change. 

III. Discussion

A. Overview

12. The Commission approves PRC-023-1, finding that it is just and reasonable, not 

unduly discriminatory or preferential and in the public interest. The Commission also 

directs the ERO to develop modifications to PRC-023-1 through its Reliability Standards 

development process to address specific concerns identified by the Commission and sets 
Docket No. RM08-13-000 - 13 - 

specific deadlines for these modifications. Similar to our approach in Order No. 693,19

we view such directives as separate from approval, consistent with our authority under 

section 215(d)(5) of the FPA to direct the ERO to develop a modification to a Reliability 

Standard. 

B. Approval of PRC-023-1

1. NOPR Proposal

13. On May 21, 2009, the Commission issued a Notice of Proposed Rulemaking 

(NOPR) proposing to approve PRC-023-1 as mandatory and enforceable.20 As a separate 

action, pursuant to section 215(d)(5) of the FPA, the Commission proposed to direct 

certain modifications to the Reliability Standard. 

2. Comments

14. While commenters universally support the Commission’s proposal to approve 

PRC-023-1,21 most commenters oppose the majority of the Commission’s proposed 

modifications. Some commenters argue that the Commission’s proposed modifications 

 19 See supra n.13. 

20 Transmission Relay Loadability Reliability Standard, Notice of Proposed 

Rulemaking, 74 FR 35830 (Jul. 21, 2009), FERC Stats. & Regs. ¶ 32,642 (2009) 

(NOPR). 

21 See, e.g., NERC Comments, EEI, TAPS, APPA, NARUC, EPSA, Exelon. 
Docket No. RM08-13-000 - 14 - 

violate Order No. 693 because they prescribe specific changes that would dictate the 

content of the modified Reliability Standard. 

3. Commission Determination

15. Pursuant to section 215(d)(2) of the FPA,22 the Commission approves PRC-023-1 

as just, reasonable, not unduly discriminatory or preferential, and in the public interest. 

The Commission finds that PRC-023-1 is a significant step toward improving the 

reliability of the Bulk-Power System in North America because it requires loadresponsive phase protection relay settings to provide essential facility protection for 

faults, while allowing the Bulk-Power System to be operated in accordance with 

established facility ratings. 

16. Also, pursuant to section 215(d)(5) of the FPA, the Commission adopts some of 

the proposed modifications in the NOPR and thus directs certain modifications to the 

Reliability Standard. Unless stated otherwise, the Commission directs the ERO to submit 

these modifications no later than one year from the date of this Final Rule. We will 

address each proposal and the specific comments received on each proposal in the 

remainder of this Final Rule. 

17. With regard to the concerns raised by some commenters about the prescriptive 

nature of the Commission’s proposed modifications, we agree that, consistent with Order 

 22 16 U.S.C. 824o(d)(2). 
Docket No. RM08-13-000 - 15 - 

 

No. 693, a direction for modification should not be so overly prescriptive as to preclude 

the consideration of viable alternatives in the ERO’s Reliability Standards development 

process. However, some guidance is necessary, as the Commission explained in Order 

No. 693: 

[I]n identifying a specific matter to be addressed in a modification . . . it is 

important that the Commission provide sufficient guidance so that the ERO 

has an understanding of the Commission’s concerns and an appropriate, but 

not necessarily exclusive, outcome to address those concerns. Without 

such direction and guidance, a Commission proposal to modify a 

Reliability Standard might be so vague that the ERO would not know how 

to adequately respond.23 

18. Thus, in some instances, while we provide specific details regarding the 

Commission’s expectations, we intend by doing so to provide useful guidance to assist in 

the Reliability Standards development process, not to impede it. As we explained in 

Order No. 693, we find that this is consistent with statutory language that authorizes the 

Commission to order the ERO to submit a modification “that addresses a specific matter” 

if the Commission considers it appropriate to carry out section 215 of the FPA.24 In this 

Final Rule, we have considered commenters’ concerns and, where a directive for 

modification appears to be determinative of the outcome, the Commission provides 

flexibility by directing the ERO to address the underlying issue through the Reliability 

23 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 185. 

24 Id. P 186. 
Docket No. RM08-13-000 - 16 - 

Standards development process without mandating a specific change to PRC-023-1.25 

Consequently, consistent with Order No. 693, we clarify that where the Final Rule 

identifies a concern and offers a specific approach to address that concern, we will 

consider an equivalent alternative approach provided that the ERO demonstrates that the 

alternative will adequately address the Commission’s underlying concern or goal as 

efficiently and effectively as the Commission’s proposal.26 

19. Consistent with section 215 of the FPA, our regulations, and Order No. 693, any 

modification to a Reliability Standard, including a modification that addresses a 

Commission directive, must be developed and fully vetted through NERC’s Reliability 

Standards development process.27 

C. Applicability

20. As proposed by NERC, PRC-023-1 does not apply to any facility operated or 

connected between 100 kV and 200 kV unless the relevant planning coordinator 

designates the facility as “critical” to the reliability of the bulk electric system. In the 

NOPR, the Commission described this as an “add in” approach to applicability.28 

 25 Id. 

26 Id. 

27 Id. P 187. 

28 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 40. 
Docket No. RM08-13-000 - 17 - 

21. Requirement R3 of PRC-023-1 directs planning coordinators to determine which 

100 kV-200 kV facilities are critical to the reliability of the bulk electric system, and 

therefore subject to the Reliability Standard; it does not, however, define “critical to the 

reliability of the bulk electric system” or provide planning coordinators with a test to 

identify critical facilities. 

1. NOPR Proposal

22. In the NOPR, the Commission stated that it expects planning coordinators to use a 

process to carry out Requirement R3 that is consistent across regions and robust enough 

to identify all facilities that should be subject to PRC-023-1. The Commission expressed 

concern that, based on the information in NERC’s petition, the “add in” approach 

proposed by NERC would fail to meet these expectations. 

23. The Commission explained that since approximately 85 percent of circuit miles of 

electric transmission are operated at or below 253 kV, the “add in” approach could, at the 

outset, effectively exempt from the Reliability Standard’s requirements a large 

percentage of facilities that should otherwise be subject to the Standard. The 

Commission also cited a letter from NERC to industry stakeholders discussing the results 

of an “add in” approach in the context of industry’s self-identification of Critical Cyber 

Assets. According to the Commission, the letter was an acknowledgement from NERC 

that the “add in” approach failed to produce a comprehensive list of Critical Cyber 
Docket No. RM08-13-000 - 18 - 

 

Assets.29 The Commission further observed that NERC failed to provide a technical 

basis for the “add in” approach, and did not support its claim that expanded application of 

PRC-023-1 would double implementation costs and distract industry resources from more 

important areas. The Commission added that PRC-023-1 was developed to prevent 

cascading outages, and that no area has a greater impact on the reliability of the bulk 

electric system than the prevention of cascading outages. 

24. The Commission emphasized that PRC-023-1 must apply to relay settings on all 

critical facilities for it to achieve its intended reliability objective.30 In order to meet this 

goal, the Commission stated that the process for identifying critical 100 kV-200 kV 

facilities must include the same system simulations and assessments as the Transmission 

Planning (TPL) Reliability Standards for reliable operation for all categories of 

contingencies used in transmission planning for all operating conditions. The 

Commission also stated that it expects a comprehensive review to identify nearly every 

100 kV-200 kV facility as a critical facility. In light of this expectation, and coupled with 

its concern about the “add in” approach, the Commission proposed to direct the ERO to 

adopt a “rule out” approach to applicability; that is, to modify PRC-023-1 so that it 

applies to relay settings on all 100 kV-200 kV facilities, with the possibility of case-by29 Id. 

30 Id. P 42. 
Docket No. RM08-13-000 - 19 - 

 

case exceptions for facilities that are not critical to the reliability of the bulk electric 

system and demonstrably would not result in cascading outages, instability, uncontrolled 

separation, violation of facility ratings, or interruption of firm transmission service.31 

25. Finally, the Commission proposed to direct the ERO to adopt an “add in” 

approach to sub-100 kV facilities that Regional Entities have identified as critical to the 

reliability of the bulk electric system.32 The Commission explained that owners and 

operators of such facilities are defined as transmission owners/operators for the purposes 

of NERC’s Compliance Registry,33 and that sub-100 kV facilities can be included in 

31 Id. P 43. 

32 Id. P 45. 

33 NERC’s Compliance Registry is a listing of organizations subject to compliance 

with mandatory Reliability Standards. See NERC Rules of Procedure, Section 500. 

NERC’s Statement of Compliance Registry Criteria, which sets forth thresholds for 

registration, defines “transmission owner/operator” as: 

III.d.1 An entity that owns or operates an integrated transmission 

element associated with the bulk power system 100 kV and 

above, or lower voltage as defined by the Regional Entity 

necessary to provide for the reliable operation of the 

interconnected transmission grid; or 

III.d.2 An entity that owns/operates a transmission element below 

100 kV associated with a facility that is included on a critical 

facilities list defined by the Regional Entity. 

See NERC Statement of Compliance Registry Criteria at 9. 
Docket No. RM08-13-000 - 20 - 

ndard. 

regional definitions of the bulk electric system.34 The Commission also stated that 

NERC failed to provide a sufficient technical record to justify excluding such facilities 

from the scope of the Reliability Sta

2. Comments

26. In response to the NOPR, the Commission received comments addressing its 

remarks about the test that planning coordinators must use to implement Requirement R3 

and its proposals to direct the ERO to adopt the “rule out” approach for 100 kV-200 kV 

facilities and the “add in” approach for sub-100 kV facilities. 

a. Comments on the Test that Planning Coordinators Must

Use to Implement Requirement R3

27. Commenters generally agree with the Commission that the process for identifying 

critical facilities pursuant to Requirement R3 should include the same simulation and 

assessments required by the TPL Reliability Standards for all operating conditions. 

However, commenters disagree with the Commission’s expectation that planning 

coordinators will identify nearly every 100 kV-200 kV facility as a critical facility. For 

 34 NERC defines the bulk electric system as follows: 

As defined by the Regional Reliability Organization, the electrical 

generation resources, transmission lines, interconnections with neighboring 

systems, and associated equipment, generally operated at voltages of 

100 kV or higher. Radial transmission facilities serving only load with one 

transmission source are generally not included in this definition. 

See NERC Glossary of Terms Used in Reliability Standards at 2. 
Docket No. RM08-13-000 - 21 - 

 

example, Duke reports that it has applied the existing TPL standards to its Midwest and 

Carolina systems and has not identified any sub-200 kV facility as a critical facility (i.e., 

there have been no showings that the loss of any such facilities could result in cascading 

outages, instability, or uncontrolled separation). Other commenters maintain that the 

Commission’s expectation is not supported by any technical evidence and depends on a 

circular definition between “above 100 kV” and “critical to the reliability of the bulk 

electric system.”35 

28. NERC recognizes the need for consistent criteria across North America for 

identifying critical 100 kV-200 kV facilities and proposes to work through industry to 

develop it.36 Although NERC did not propose a test in PRC-023-1, in its comments it did 

provide the suggestions for identifying operationally significant 100 kV-200 kV facilities 

that the NERC System Protection and Control Task Force provided to Regional Entities 

in 2004 and 2005 during the voluntary Beyond Zone 3 relay review and mitigation 

program.37 During that program, NERC suggested that Regional Entities identify: 

35 See, e.g., Basin, Exelon, and WECC. 

36 NERC Comments at 12. 

37 For a discussion of the Beyond Zone 3 relay review and mitigation program, see

infra P 34. 
Docket No. RM08-13-000 - 22 - 

 

All circuits that are elements of flowgates[38] in the Eastern 

Interconnection, Commercially Significant Constraints in the Texas 

Interconnection, or Rated Paths in the Western Interconnection. This 

includes both the monitored and outage element for OTDF [Outage 

Transfer Distribution Factor] sets.[39] 

All circuits that are elements of system operating limits (SOLs) and 

interconnection reliability operating limits (IROLs), including both 

monitored and outage elements. 

All circuits that are directly related to off-site power supply to nuclear 

plants. Any circuit whose outage causes unacceptable voltages on the offsite power bus at a nuclear plant must be included, regardless of its 

proximity to the plant. 

All circuits of the first 5 limiting elements (monitored and outaged 

elements) for transfer interfaces[40] determined by regional and 

interregional transmission reliability studies. If fewer than 5 limiting 

elements are found before reaching studied transfers, all should be listed. 

Other circuits determined and agreed to by the reliability 

authority/coordinator and the Regional Reliability Organizations. 

38 A “flowgate” is a single or group of transmission elements intended to model 

MW flow impact relating to transmission limitations and transmission service outage. 

See Final Black Report at 214. Flowgates are operationally significant for the purpose of 

ensuring desirable system performance because an actual outage would present the 

modeled physical limitations on the bulk electric system. 

39 In the post-contingency configuration of a system under study, Outage Transfer 

Distribution Factor refers to the measure of the responsiveness or change (expressed in 

percent) in electrical loadings on transmission system facilities due to a change in electric 

power transfer from one area to another with one or more system facilities removed from 

service. 

40 An “interface” is the specific set of transmission elements between two areas or 

between two areas comprising one or more electrical systems. See Final Blackout Report 

at 215. An interface is operationally significant for the purpose of ensuring desirable 

system performance because an outage of an interface would affect IROLs. 
Docket No. RM08-13-000 - 23 - 

29. In its comments, APPA proposes that the Commission direct NERC to develop a 

process whereby each region can develop a specific methodology to ensure consistent, 

verifiable identification of critical facilities. 

b. Comments on the “Rule Out” Approach

30. Commenters unanimously oppose the “rule out” approach. In general, they argue 

that it is unnecessary, extremely costly, and potentially detrimental to reliability. 

31. NERC, EEI, and WECC argue that the cascade of 138 kV lines that occurred 

during the August 2003 blackout would not have occurred if the 345 kV lines in their 

vicinity had not tripped, and that the 345 kV lines would not have tripped if PRC-023-1 

had been in effect prior to the blackout.41 EEI, PG&E, and SRP add that whenever a 

facility between 100 kV and 200 kV trips on load, it is almost always because of 

preceding faults at higher voltages. 

32. Some commenters argue that the majority of facilities between 100 kV and 

200 kV are not critical to the reliability of the bulk electric system and are unlikely to 

contribute to cascading outages at higher voltages. APPA, EEI, and WECC state that 

most wide-area bulk power transfers flow on high voltage facilities, while most 

sub-200 kV facilities support local distribution service.42 SRP asserts that a malfunction 

 41 See, e.g., NERC Comments at 10, 16. 

42 SRP and Y-WEA emphasize that this is especially true in the western 

interconnection, where sub-200 kV facilities are generally used as localized means for 

(continued...) 
Docket No. RM08-13-000 - 24 - 

 

on a 100 kV-200 kV line typically causes an outage only for the load connected to the 

faulted part of the line, leaving the rest of the line unaffected; PG&E makes the related 

claim that the tripping of a 100 kV-200 kV facility generally has a low impact on the 

reliability of higher voltage systems, even when the two systems run in parallel. APPA 

argues that cascading outages at higher voltages are unlikely to be arrested by relay 

action at lower voltages. EEI adds that many 100 kV-200 kV facilities are designed to 

support local distribution service and their related protection systems are set to ensure 

separation, including load shedding, if disturbances or system events take place. EEI 

asserts that these systems ensure “controlled separation” that, by definition, does not 

involve the Bulk-Power System. 

33. Commenters also argue that the “rule out” approach is a costly and inefficient use 

of limited industry resources that will place an unreasonable burden on small entities and 

require utilities to incur unnecessary upfront costs, forego other important initiatives, and 

direct money and personnel away from the work necessary to ensure the day-to-day 

reliability of the bulk electric system. 

34. NERC states that it modeled PRC-023-1 on two post-blackout relay review and 

mitigation programs (the Zone 3 Review and Beyond Zone 3 Review) that focused 

primarily on facilities operated at or above 200 kV, and that these programs give it a 

distributing electricity to moderately sized and geographically distant load centers. See

also ElectriCities and NWCP. 
Docket No. RM08-13-000 - 25 - 

 

basis for concluding that the costs of the “rule out” approach are extremely high.43 

NERC reports that these programs took over three years to complete, required close to 

150,000 hours of labor, cost almost $18 million, and resulted in mitigation costs 

(equipment change-outs or additions) of approximately $65 million, or $111,500 per 

terminal. Based on a survey of industry conducted after the NOPR, NERC estimates that 

a review and mitigation program for all facilities between 100 kV and 200 kV would far 

exceed these costs in time and money. NERC estimates that such a program would entail 

review of approximately 53,000 terminals, require close to 340,000 hours of labor, and 

cost almost $41 million.44 Based on the results of the previous review programs, NERC 

estimates that at least 11,400 terminals could be out-of-compliance and that mitigation 

could take between 5 and 10 years and cost approximately $590 million.45 In contrast, 

NERC estimates that the “add in” approach would entail review of only 2,400 terminals 

and require mitigation for approximately 500, roughly 240 of which would require 

equipment replacement.46

43 The Zone 3 Review examined 10,914 terminals operating at or above 200 kV. 

The Beyond Zone 3 Review examined 12,273 terminals operating at or above 200 kV 

and operationally significant terminals operating between 100 kV and 200 kV. NERC 

Comments at 9-16. 

44 Id. at 13-14. NERC adds that 114 transmission owners operating 100 kV-200 

kV lines responded to the survey. 

45 Id. at 14. 

46 Id. at 15. 
Docket No. RM08-13-000 - 26 - 

 

35. Some commenters argue that the “rule out” approach may adversely affect 

reliability. Exelon is concerned that the “rule out” approach may unintentionally result in 

the over-inclusion of facilities subject to PRC-023-1. Exelon believes that such overinclusion will take a known and successful backup protection scheme and make it less 

effective. Exelon explains that over-inclusion will increase the risk of certain instances 

of backup relaying not tripping when it should, thus allowing what would otherwise be a 

minor disturbance to expand unnecessarily.47 Consumers Energy and Entergy argue that 

the “rule out” approach will require entities to divert scarce resources from other duties 

that are essential to reliability, thereby adversely affecting reliability. Basin argues that 

the complexity of integrating PRC-023-1 with other Reliability Standards for lower 

voltage lines will divert personnel from more important aspects of the Reliability 

Standards and adversely affect reliability. 

36. In addition to these arguments, commenters oppose the “rule out” approach on the 

grounds that it: (1) fails to give due weight to the technical expertise of the ERO, as 

required by section 215(d)(2) of the FPA; (2) violates Order No. 693 because it 

prescribes a specific change that will dictate the content of the modified Reliability 

47 See also Ameren at 8. 
Docket No. RM08-13-000 - 27 - 

 

Standard;48 (3) is inconsistent with the Commission’s statements in Order No. 672 about 

the cost of Reliability Standards;49 (4) rests on the unsupported assumption that planning 

coordinators will fail to produce a comprehensive list of critical facilities; and 

(5) mischaracterizes NERC’s letter expressing concern about the use of an “add in” 

approach in the Critical Cyber Assets survey.50 

37. In the event that the Commission adopts the “rule out” approach, commenters 

argue that the Commission should immediately confirm the following exclusions: 

(1) facilities that are not part of a defined and routinely monitored flowgate; (2) radial 

transmission lines, because they are specifically excluded from the bulk electric system 

and are not critical to the reliability of the bulk electric system;51 and (3) Category D 

48 See e.g., TAPS, APPA, EEI, Ameren, Manitoba Hydro, Georgia Transmission, 

Tri-State, CRC, EEI, APPA, Ameren, TANC, Fayetteville Public Works Commission, 

and LES. 

49 In Order No. 672, the Commission stated that “[a] proposed Reliability Standard 

does not necessarily have to reflect the optimal method, or ‘best practice,’ for achieving 

its reliability goal without regard to implementation cost . . . . [but] should[,] however[,] 

achieve its reliability goal effectively and efficiently;” Rules Concerning Certification of 

the Electric Reliability Organization; and Procedures for the Establishment, Approval, 

and Enforcement of Electric Reliability Standards, Order No. 672, FERC Stats. & Regs. 

¶ 31,204, at P 328, order on reh’g, Order No. 672-A, FERC Stats. & Regs. ¶ 31,212 

(2006). 

50 See e.g., Exelon, PG&E, EEI, Basin, and TAPS. 

51 See e.g., ElectriCities, NWCP, Palo Alto, PSEG Companies, Pacific Northwest 

State Commissions, Y-WEA, and Filing Cooperatives. 
Docket No. RM08-13-000 - 28 - 

Contingencies, because they involve the loss of multiple transmission facilities caused by 

the outage of transmission facilities other than those relevant to the Reliability Standard. 

38. Commenters also disagree with what they describe as the Commission’s 5-part test 

for case-by-case exceptions from the “rule out” approach, that is, its proposal to permit 

exceptions for facilities that demonstrably would not result in: (1) cascading outages; 

(2) instability; (3) uncontrolled separation; (4) violation of facility ratings; or 

(5) interruption of firm transmission service. 

39. At the outset, commenters assert that they do not understand the relationship 

between the 5-part test for exceptions from the “rule out” approach and the 

Commission’s insistence that the “add in” process must include the same simulations and 

assessments as the TPL Reliability Standards. Commenters are unsure whether the 5-part 

test is in addition to, or in lieu of, the TPL assessments. 

40. Commenters also challenge the substance of the 5-part test, generally arguing that 

it requires more than a showing that a facility is unlikely to contribute to cascading 

thermal outages and introduces more rigorous requirements than those in the TPL 

Reliability Standards. Specifically, APPA, Duke, Exelon, and TAPS argue that 

interruption of firm transmission service and violation of facility ratings do not belong as 

elements of the test because: (1) they do not result in instability, uncontrolled separation, 

or cascading failures, and are absent from the definition of “Reliable Operation” in 
Docket No. RM08-13-000 - 29 - 

section 215 of the FPA;52 (2) avoiding an interruption of firm transmission service is a 

business issue; (3) a requirement specifying that the loss of a 138 kV line cannot result in 

interruption of local load goes beyond the requirements of existing Reliability Standards; 

(4) the loss of a 138 kV line does not show a loss of bulk electric system reliability; and 

(5) “violation of facility ratings” is unduly vague and over-broad because it is not 

restricted to bulk electric system facilities other than the facility in question and is not 

focused on violation of emergency ratings caused by an outage of the facility in question. 

41. Commenters also argue that NERC should develop the test for exclusions and that 

there should be some mechanism for entities to challenge criticality determinations. For 

example, APPA argues that the Regional Entity should establish a process for entities to 

challenge criticality determinations. 

c. Comments on Proposal to Include Sub-100 kV Facilities 

42. Commenters also address the Commission’s proposal to direct the ERO to adopt 

an “add in” approach to sub-100 kV facilities, with most objecting to what they perceive 

as the Commission’s view of the Compliance Registry.53 NERC argues that the 

 52 Section 215 defines “Reliable Operation” as “operating the elements of the 

bulk-power system within equipment and electric system thermal, voltage, and stability 

limits so that instability, uncontrolled separation, or cascading failures of such system 

will not occur as a result of a sudden disturbance, including a cybersecurity incident, or 

unanticipated failure of system elements.” 16 U.S.C. 824o(a)(4). 

53 See e.g., NERC, EEI, TAPS, TANC, Ontario Generation, SWTDUG, and 

APPA. 
Docket No. RM08-13-000 - 30 - 

 

Commission mischaracterized the nature and purpose of the Compliance Registry by 

suggesting that entities on the Registry must comply with all Reliability Standards for all 

of their facilities.54 NERC explains that the Compliance Registry does not specify which 

entities must comply with any particular Reliability Standard, but that each individual 

Standard specifies the entities and the facilities that are subject to it. TAPS and APPA 

assert that a facility may be “critical” for the purpose of inclusion on the Compliance 

Registry, but not “operationally significant” for the purpose of avoiding cascading 

thermal outages. For example, TAPS states that a sub-100 kV line that connects to a 

black start unit and is designated as part of a transmission operator’s restoration plan 

would be deemed critical for Compliance Registry purposes, but may not be 

operationally significant for purposes of thermal cascading outages.55 

43. Several commenters request that the Commission confirm their understanding of 

what is required if the Commission adopts its proposal. ERCOT and TAPS request 

confirmation that the Reliability Standard will apply only to those sub-100 kV facilities 

that are already in the Compliance Registry, and that future registration will be subject to 

a case-by-case demonstration of criticality. Likewise, SWTDUG is concerned that the 

Commission’s proposal will require non-registered public power entities with sub-100 kV 

54 See also TANC and Ontario Generation. 

55 TAPS at 16; see also APPA at 28. 
Docket No. RM08-13-000 - 31 - 

 

facilities to become Registered Entities. ERCOT also requests confirmation that the only 

required revision to the Reliability Standard would be the addition of sub-100 kV 

facilities to the applicability section. ISO New England requests confirmation that the 

Commission does not intend to create an enforceable obligation against Regional Entities 

by directing them to undertake—solely for the purpose of compliance with PRC-023-1—

a process to determine which sub-100 kV facilities are critical to the reliability of the 

bulk electric system. ISO New England asserts that NERC has already delegated to 

Regional Entities the role of designating critical sub-100 kV facilities as part of the 

Compliance Registry process.56 ISO New England seeks clarification that the 

Commission’s proposal merely requires the addition of a cross-reference to previous 

designations of criticality made pursuant to the Compliance Registry process. 

44. ITC, IRC, and IESO/Hydro One support the Commission’s proposal. These 

commenters argue that a proactive approach should be used to identify any facilities 

critical to the reliability of the bulk electric system. 

45. NERC and EEI oppose the Commission’s proposal; however, both concede that it 

may have merit and should be studied through the Reliability Standards development 

process.57 SWTDUG and TAPS oppose the Commission’s proposal and argue that the 

56 ISO New England at 3. 

57 NERC Comments at 18-19; EEI at 17-18. 
Docket No. RM08-13-000 - 32 - 

Final Blackout Report does not support extending the Reliability Standard to relay 

settings on sub-100 kV facilities. TAPS maintains that the Commission must give “due 

weight” to NERC’s exclusion of sub-100 kV facilities. 

46. EPSA argues that the Commission’s proposal lacks technical support and fails to 

identify a specific reliability gap. EPSA contends that the Commission should use 

“Reliability Engineering” to determine if its project has a technical basis. EEI argues that 

few sub-100 kV facilities are critical to the reliability of the bulk electric system. EEI 

states that because it usually requires multiple 69 kV lines to replace one 138 kV line, it 

is highly unlikely that sub-100 kV facilities will cause a major cascade. EEI asserts that 

it is much more likely that sub-100 kV facilities will trip to end a cascade, as occurred 

during the August 2003 blackout. 

3. Commission Determination

47. As discussed more fully below, we decline to direct the ERO to adopt the “rule 

out” approach for 100 kV-200 kV facilities. However, we adopt the NOPR proposal and 

direct the ERO to modify PRC-023-1 to apply an “add in” approach to certain sub-100 

kV facilities that Regional Entities have already identified or will identify in the future as 

critical facilities for the purposes the Compliance Registry.58 Finally, we direct the ERO 

to modify Requirement R3 of the Reliability Standard to include the test that planning 

 58 Examples of such facilities include black start generation and the “cranking 

path” from the generators to the bulk electric system. 
Docket No. RM08-13-000 - 33 - 

coordinators must use to identify sub-200 kV facilities that are critical to the reliability of 

the bulk electric system. 

a. “Rule Out” Approach

48. We will not direct the ERO to adopt the “rule out” approach. After further 

consideration, we conclude that our concerns about the “add in” approach can be 

addressed by directing the ERO to modify Requirement R3 of the Reliability Standard to 

specify a comprehensive and rigorous test that all planning coordinators must use to 

identify all critical facilities. 

49. In the NOPR, the Commission explained that PRC-023-1 must apply to relay 

settings on all critical facilities between 100 kV and 200 kV for it to achieve its intended 

reliability objective. The Commission also stated that planning coordinators must use a 

process to carry out Requirement R3 that is consistent across regions and robust enough 

to identify all facilities that should be subject to the Reliability Standard. The 

Commission expressed concern, however, that NERC’s “add in” approach could 

effectively exempt from the Reliability Standard’s Requirements a large percentage of 

facilities that should otherwise be subject to the Standard. Since NERC did not propose 

any test for the Commission to consider, the Commission proposed the “rule out” 

approach to ensure that planning coordinators identify all critical facilities between 

100 kV and 200 kV. 
Docket No. RM08-13-000 - 34 - 

50. After reflecting on the rationale behind the “rule out” approach — namely, the 

goal of ensuring that planning coordinators identify all critical facilities between 100 kV 

and 200 kV — and considering the comments, we conclude that, from a reliability 

standpoint, it should not matter whether PRC-023-1 employs an “add in” approach or a 

“rule out” approach because both approaches should ultimately result in the same list of 

critical facilities. In other words, given a uniform and robust test, the facilities that would 

be “added in” under an “add in” approach should be the same as the facilities that would 

remain subject to the Reliability Standard after non-critical facilities are ruled out under 

the “rule out” approach. Instead of concerning ourselves with the merits of an “add in” 

or “rule out” approach, the Commission will focus on the test methodology that a 

planning coordinator uses to either “add in” or “rule out” a facility. If that test is lacking, 

PRC-023-1’s reliability objective will not be achieved regardless of whether an “add in” 

approach or a “rule out” approach is adopted. Consequently, we decline to adopt the 

NOPR proposal and will not require the ERO to adopt the “rule out” approach. Instead, 

as discussed below, we direct the ERO to modify Requirement R3 of the Reliability 

Standard to specify the test that planning coordinators must use to identify all critical 

facilities. 

51. In light of our decision, we do not need to address commenters’ objections to the 

“rule out” approach or speculation about the number of 100 kV-200 kV facilities that are 

critical to the reliability of the Bulk-Power System. Nevertheless, we do not accept the 
Docket No. RM08-13-000 - 35 - 

 

claim that if PRC-023-1 had been in effect at the time of the August 2003 blackout, it 

would have prevented the 345 kV lines from tripping and therefore prevented the 

100 kV-200 kV lines from tripping. We also disagree with commenters’ claim that the 

majority of facilities between 100 kV and 200 kV are unlikely to contribute to cascading 

outages at higher voltages. 

52. We disagree with commenters’ assertion that if PRC-023-1 had been in effect at 

the time of the August 2003 blackout, it would have prevented the 345 kV lines from 

tripping and therefore prevented the 100 kV-200 kV lines from tripping. On the day of 

the blackout, the Harding-Chamberlin, Hanna-Juniper, and Star-South Canton 345 kV 

lines all tripped in a span of less than 45 minutes. Each of these lines tripped and locked 

out because of contact with an overgrown tree.59 As each line failed, its outage increased 

the load on the remaining 138 kV and 345 kV lines, including the 345 kV Sammis-Star 

line,60 and shifted power flows to other transmission paths. Starting at 15:39 EDT, the 

first of an eventual sixteen 138 kV lines began to fail. The tripping of these 138 kV lines 

occurred because the loss of the combination of the Hardin-Chamberlin, Hanna-Juniper, 

and Star-South Canton 345 kV lines overloaded the 138 kV system with electricity 

59 Final Blackout Report at 57-61; 63-64. 

60 Id. at 70. 
Docket No. RM08-13-000 - 36 - 

 

flowing toward the Akron and Cleveland loads.61 In other words, the cascade of 138 kV 

lines was precipitated by faults caused by tree contact, not protective relays, and would 

not have been prevented if PRC-023-1 had been in effect before the blackout. 

53. As the 138 kV lines opened, they blacked out customers in Akron and in the area 

west and south of Akron, ultimately dropping about 600 MW of load.62 Even this load 

shedding was not enough to offset the cumulative effect of the 138 kV line outages on the 

increased loadings of the 345 kV Sammis-Star line. The Sammis-Star line tripped at 

16:05:57 EDT and triggered a cascade of interruptions on the high voltage system, 

causing electrical fluctuations and facility trips such that within seven minutes the 

blackout rippled from the Cleveland-Akron area across much of the northeast United 

States.63 

54. Unlike the Hardin-Chamberlin, Hanna-Juniper, and Star-South Canton lines, 

which tripped because of tree contact, the Sammis-Star line tripped due to protective zone 

3 relay action that measured low apparent impedance (depressed voltage divided by 

abnormally high line current).64 There was no fault and no major power swing at the 

time of the trip; rather, high flows above the line’s emergency rating together with 

61 Id. at 69-70. 

62 Id. at 68. 

63 Id. at 74. 

64 Id. at 77-78. See Figure 6.4. 
Docket No. RM08-13-000 - 37 - 

 

depressed voltage caused the overload to appear to the protective relays as a remote fault 

on the system.65 In effect, the relay could no longer differentiate between a remote threephase fault and an exceptionally high loading condition. The relay operated as it was 

designed to do.66

55. To the extent that commenters’ argument is that PRC-023-1 would have prevented 

the loss of the Sammis-Star line, and therefore the subsequent spread of the blackout, we 

do not think that it is possible to definitively reach these conclusions on the present 

record. 

56. Requirement R1 of PRC-023-1 directs entities to evaluate relay loadability at 0.85 

per unit voltage and a power factor angle of 30 degrees. Figure 6.4 of the Final Blackout 

Report indicates that the power factor angle recorded at the time the Sammis-Star line 

tripped was about 27 degrees. Although the system was in a marginally stable operating 

stage, it would not require major changes to effect a further change on the loading or 

further increasing the power factor angle on this line to beyond 30 degrees. In other 

words, purely from the power factor angle viewpoint, the Sammis-Star line trip may still 

have occurred even if the relay loadability evaluation requirement of 30 degrees was met. 

In fact, in a white paper explaining the engineering assumptions and rationales behind the 

65 Id. at 77. 

66 Id. 
Docket No. RM08-13-000 - 38 - 

 

Requirements in PRC-023-1, the NERC System Protection and Control Task Force 

specifically stated that: 

[T]he most important point to understand [about the relay loadability evaluation 

requirement in Requirement R1] is that the loadability recommendations are not 

absolute system conditions. They represent a typical system operation point during 

an extreme system condition. The voltage at the relay may be below the 0.85 per 

unit voltage and the power factor angle may be greater than 30 degrees. It is up to 

the relay settings engineer to provide the necessary margin as is done in all relay 

settings.67 

We agree with the NERC System Protection and Control Task Force, and caution that 

setting relays pursuant to PRC-023-1 simply based on a static and typical system 

operation point, without validating the relay settings based on system conditions that the 

relays could experience, and without acceptable margins applied to the minimum 

voltages and power factor angles, may not achieve the reliability goals intended by PRC023-1. 

57. Consequently, we believe that it is not possible to conclude whether the SammisStar line would have tripped on loadability if PRC-023-1 had been in effect without first 

setting its zone 3 relay pursuant to PRC-023-1 and then validating the setting against the 

voltages, currents, and power factor angles that were recorded during the August 2003 

Blackout. In fact, it is our view that a similar process should be followed for the 345 kV 

67 NERC Planning Committee, System Protection and Control Task Force, 

“Increase Line Loadability by Enabling Load Encroachment Functions of Digital 

Relays,” December 7, 2005 at A-1. 
Docket No. RM08-13-000 - 39 - 

 

lines in Michigan that tripped following the loss of Sammis-Star line to determine 

whether PRC-023-1 would have prevented the blackout. 

58. We also disagree with commenters’ assertion that that majority of facilities 

between 100 kV and 200 kV are unlikely to contribute to cascading outages at higher 

voltages. Prior to the dynamic cascading stage that began with the loss of the 345 kV 

Sammis-Star line, when the system was still in a marginally stable operating state (albeit 

not within IROLs, as shown in Figure 5.12 in the Final Blackout Report), it was the loss 

of several 138 kV facilities that contributed to the subsequent increased loading on the 

345 kV Sammis-Star line and resulted in its tripping.68 A more recent example of a 

cascade initiating at the 138 kV voltage level and spreading to higher voltages is the 

Florida Power and Light 2008 blackout event. This event started at the 138 kV level and 

cascaded into additional 138 kV, 230 kV, and 500 kV facilities. Because the operation of 

the protective relay is dependent on the apparent impedance, i.e. voltage and current 

quantities as measured by the relay irrespective of voltage class, application of 

PRC-023-1 at only the higher voltage would not have prevented these events. We 

believe that only a valid assessment with an acceptable set of test criteria could determine 

whether 100 kV-200 kV facilities are critical facilities, and therefore whether they need 

to be set pursuant to PRC-023-1 to prevent such undesirable system performance. 

68 Final Blackout Report at 64. 
Docket No. RM08-13-000 - 40 - 

59. Finally we agree with APPA that cascading outages at higher voltages are unlikely 

to be arrested by relay action at lower voltages. Reliability Standard PRC-023-1 is for 

preventing inadvertent tripping of Bulk-Power System facilities which could then initiate 

cascading outages at any voltage level, and not for arresting cascading outages. 

b. “Add in” Approach to Sub-100 kV Facilities

60. With respect to sub-100 kV facilities, we adopt the NOPR proposal and direct the 

ERO to modify PRC-023-1 to apply an “add in” approach to sub-100 kV facilities that 

are owned or operated by currently-Registered Entities or entities that become Registered 

Entities in the future, and are associated with a facility that is included on a critical 

facilities list defined by the Regional Entity.69 We also direct that additions to the 

Regional Entities’ critical facility list be tested for their applicability to PRC-023-1 and 

made subject to the Reliability Standard as appropriate. 

61. Most of the comments opposing the Commission’s proposal regarding sub-100 kV 

facilities relate to what commenters perceive to be the Commission’s view of the 

relationship between individual Reliability Standards and the Compliance Registry. For 

example, NERC argues that the Commission mischaracterized the nature and purpose of 

the Compliance Registry by suggesting that entities on the Registry must comply with all 

 69 As mentioned above, section III.d.2 of the Statement of Compliance Registry 

Criteria defines “transmission owner/operator” as: “[a]n entity that owns/operates a 

transmission element below 100 kV associated with a facility that is included on a critical 

facilities list defined by the Regional Entity.” 
Docket No. RM08-13-000 - 41 - 

Reliability Standards for all of their facilities without regard to the applicability 

provisions of individual Standards. We did not intend to create this impression. We 

agree with NERC that the Compliance Registry does not specify which entities must 

comply with any particular Reliability Standard. Rather, the applicability provision of 

each individual Standard specifies the categories of entities, i.e., functions, and at times 

the categories of facilities that are subject to it. 

62. We also agree with TAPS and APPA that it is possible, at least in theory, that a 

sub-100 kV facility that has been identified by a Regional Entity as critical for the 

purposes the Compliance Registry might not be “critical” with respect to PRC-023-1. 

Thus, we clarify that we do not require the modified Reliability Standard to apply to all 

sub-100 kV facilities that have been identified by Regional Entities as critical facilities, 

but only to those that have been identified by Regional Entities as critical facilities and 

are also identified by planning coordinators, pursuant to the test directed to be developed 

herein, as critical to the reliability of the Bulk-Power System. In other words, the 

modification that we direct in this Final Rule extends the scope of the Reliability 

Standard to include any sub-100 kV facility that is: (1) owned or operated by a currentlyRegistered Entity or an entity that becomes a Registered Entity in the future; 

(2) associated with a facility that is included on a critical facilities list defined by the 
Docket No. RM08-13-000 - 42 - 

Regional Entity; (3) employing load-responsive phase protection relays in its protection 

system(s); and (4) identified by the test directed to be developed herein.70

63. Along these same lines, ERCOT, SWTDUG, and TAPS are concerned that the 

Commission’s proposal will require non-registered public power entities with sub-100 kV 

facilities to become Registered Entities. As we have said, our directive applies only to 

sub-100 kV facilities that are owned or operated by currently-Registered Entities or 

entities that become Registered Entities in the future, and are associated with a facility 

that is included on a critical facilities list defined by the Regional Entity; it is not intended 

to supplant the process that Regional Entities use to determine if a sub-100 kV facility 

should be identified as a critical facility or if an entity should be a Registered Entity. 

Similarly, our purpose is not to extend the definition or the scope of the bulk electric 

system sub rosa; it is to ensure that PRC-023-1 applies to all critical facilities as 

identified in the applicability section so that the Reliability Standard can achieve its 

reliability objective. Consequently, we do not intend to require any non-Registered 

Entity to register on account of PRC-023-1. Nevertheless, there might be sub-100 kV 

facilities that are owned or operated by non-Registered Entities that are identified by 

 70 Consistent with Order No. 716, we expect that sub-100 kV facilities that are 

needed to supply the auxiliary power system of a Nuclear Power plant will be included in 

both determinations. See Mandatory Reliability Standard for Nuclear Plant Interface 

Coordination, Order No. 716, 125 FERC ¶ 61,065 (2008), at P 51-53, order on reh’g, 

Order No. 716-A, 126 FERC ¶ 61,122 (2009). 
Docket No. RM08-13-000 - 43 - 

 

planning coordinators, pursuant to the test directed to be developed herein, as critical 

facilities. While we do not require that these entities become Registered Entities solely 

due to PRC-023-1, if a planning coordinator applying the test directed to be developed 

herein identifies a sub-100 kV facility that belongs to a non-Registered Entity as a critical 

facility, we expect that the planning coordinator will inform the Regional Entity and that 

the Regional Entity will consider this information in light of its existing registration 

guidelines and procedures.71 Similarly, we expect that Regional Entities will consider 

this information when determining whether a sub-100 kV facility should be included in a 

regional definition of the bulk electric system.72 

64. With respect to ISO New England’s request for confirmation that the Commission 

does not intend to create an enforceable obligation against Regional Entities by directing 

them to undertake—solely for the purpose of compliance with PRC-023-1—a process to 

determine which sub-100 kV facilities are critical to the reliability of the Bulk-Power 

System, it should be clear from what we have already said that we do not intend to create 

such an obligation. As we have explained, our directive requires planning coordinators, 

not Regional Entities, to determine which sub-100 kV facilities should be subject to the 

71 In general, we expect that the results of the planning coordinator analysis and 

the processes used by the Regional Entities to identify critical facilities would have 

similar outcomes. 

72 We note that the definition of the bulk electric system is subject to change. See

Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 77. 
Docket No. RM08-13-000 - 44 - 

 

Reliability Standard. Moreover, we agree with ISO New England’s assertion that 

Regional Entities have already been delegated by NERC the role of designating critical 

sub-100 kV facilities as part of the Compliance Registry process.73 

65. Some commenters question the technical basis for extending PRC-023-1 to sub100 kV facilities. For example, EEI argues that because it usually requires multiple 

69 kV lines to replace one 138 kV line, it is highly unlikely that sub-100 kV facilities will 

cause a major cascade and much more likely that sub-100 kV facilities will trip to end a 

cascade, as occurred during the August 2003 blackout. EPSA argues that the 

Commission should apply “Reliability Engineering” to determine whether there is a 

technical basis for its proposal. SWTDUG and TAPS argue that the Final Blackout 

Report does not support extending the Reliability Standard to relay settings on sub-100 

kV facilities. 

66. We will not follow EPSA’s suggestion to use Reliability Engineering to identify 

critical facilities. In our view, it is more appropriate to identify critical sub-100 kV 

facilities (and, for that matter, critical 100 kV-200 kV facilities) by using established 

criteria specific to the electric industry.74 The TPL Reliability Standards establish 

73 ISO New England at 3. See also Order No. 693, FERC Stats. & Regs. ¶ 31,242, 

at P 101. 

74 EPSA states that “Reliability Engineering” is currently used to develop 

modeling and maintenance strategies for complex systems, including multiple failure 

(continued...) 
Docket No. RM08-13-000 - 45 - 

f 

We 

ational 

 

desired system performance requirements specific to a set of contingencies under a set o

base cases that cover critical system conditions of the Bulk-Power System, while 

Reliability Engineering, as described by EPSA, is primarily used in reliability-centered 

maintenance to assess the optimum intervals and practices for facility maintenance. 

strongly believe that, for the purposes of PRC-023-1, it is appropriate to use requirements 

that are specific to the electric industry and that are supported by decades of found

planning and operating principles and experiences and that are embedded in the TPL 

Reliability Standards rather than criteria that may be more appropriate to maintenance 

practices. 

67. We also reject EEI’s claim that there is no technical basis for extending 

PRC-023-1 to sub-100 kV facilities. Relay settings on such facilities should be subject to 

PRC-023-1 because their loss can also affect the reliability of the Bulk-Power System. 

We also reject TAPS’s assertion that the Commission must exclude sub-100 kV facilities 

since the Commission is required under section 215(d)(2) of the FPA to give “due 

weight” to the technical expertise of the ERO. NERC has not provided a sufficient 

technical justification to support the exclusion of sub-100 kV facilities. In its comments, 

NERC states that extending PRC-023-1 to sub-100 kV facilities “may have merit” and 

testing, which has been applied to systems such as oil pipelines and civil infrastructures. 

EPSA at 6. 
Docket No. RM08-13-000 - 46 - 

 

“would require further study,”75 indicating that it did not affirmatively consider 

subjecting certain sub-100 kV facilities to the Reliability Standard and then reject the 

idea on the basis of its technical expertise. Moreover, NERC has not offered a technical 

basis for opposing the Commission’s proposal. NERC’s comments on the Commission’s 

proposal pertain exclusively to the relationship between the Compliance Registry and 

entities’ obligations to comply with Reliability Standards. Contrary to TAPS’s assertion, 

NERC does not offer a technical argument against including certain sub-100 kV facilities 

in PRC-023-1. 

68. Similarly, with respect to EEI’s and NERC’s claim that any expansion of the 

Reliability Standard must be developed through the Reliability Standards development 

process, we clarify that, as with our other directives in this Final Rule, we do not 

prescribe this specific change as an exclusive solution to our reliability concerns 

regarding sub-100 kV facilities. As we have stated, the ERO can propose an alternative 

solution that it believes is an equally effective and efficient approach to addressing the 

Commission’s reliability concerns about the absence of sub-100 kV facilities from 

PRC-023-1. Moreover, while we expect planning coordinators to use the same test to 

identify critical sub-100 kV facilities as they use to identify critical 100 kV-200 kV 

facilities, the ERO is free, pursuant to Order No. 693, to propose a modified Reliability 

75 NERC Comments at 18. 
Docket No. RM08-13-000 - 47 - 

Standard that contains a different test for sub-100 kV facilities, provided that the test 

represents an “equivalent alternative approach.” 

c. Test for Identifying Sub-200 kV Facilities

 i. Overview

69. Finally, pursuant to section 215(d)(5) of the FPA, we direct the ERO to modify 

Requirement R3 of the Reliability Standard to specify the test that planning coordinators 

must use to determine whether a sub-200 kV facility is critical to the reliability of the 

Bulk-Power System. We direct the ERO to file its test, and the results of applying the 

test to a representative sample of utilities from each of the three Interconnections, for 

Commission approval no later than one year from the date of this Final Rule.76 

70. As we explained above, the Commission proposed to direct the ERO to adopt the 

“rule out” approach for 100 kV-200 kV facilities because it was concerned that NERC’s 

“add in” approach would effectively exempt a large percentage of facilities that should 

otherwise be subject to the Reliability Standard. Contrary to the suggestion of some 

commenters, the Commission’s concern was not based on a latent distrust of planning 

coordinators, but on the absence of a mandatory test in the Reliability Standard for 

 76 We expect that the representative samples will include large and small, rural and 

metropolitan entities reflecting various topologies. 
Docket No. RM08-13-000 - 48 - 

 

planning coordinators to use to identify critical facilities.77 Without such a test, the 

Commission has no way of determining whether the “add in” approach will result in a 

comprehensive list of critical facilities. As we also explained above, because the “rule 

out” approach and the “add in” approach should ultimately result in the same list of 

critical facilities, the choice between them is less important, from a reliability standpoint, 

than the test that planning coordinators must use to determine whether a facility is a 

critical facility. We conclude, therefore, that the lack of such a mandatory test is a matter 

that must be addressed by the ERO to ensure that the Reliability Standard meets its 

reliability objective. Otherwise, there is no guarantee that all planning coordinators will 

use comprehensive and rigorous criteria that is consistent across regions to identify all 

critical sub-200 kV facilities, leaving the Bulk-Power System vulnerable to similar 

problems that resulted in the cascade during the August 2003 blackout. 

71. Consistent with Order No. 693, we provide “sufficient guidance so that the ERO 

has an understanding of the Commission’s concerns and an appropriate, but not 

necessarily exclusive, outcome to address those concerns.”78 In this way, we ensure that 

the Commission’s directive is not “so vague that the ERO would not know how to 

77 NERC agrees that there must be consistent criteria for determining which 

100 kV-200 kV facilities are critical facilities. Id. at 12. 

78 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 185. 
Docket No. RM08-13-000 - 49 - 

 

adequately respond.”79 Thus, below we provide guidance for the development of a test to 

determine critical facilities.80 

72. We first observe that PRC-023-1 directs planning coordinators to identify facilities 

that are “critical to the reliability of the bulk electric system.” In contrast, 

Recommendation 21A of the Final Blackout Report refers to “operationally significant” 

facilities. APPA, Exelon, and TAPS argue that, in the context of the Reliability Standard, 

“critical to the reliability of the bulk electric system” and “operationally significant” carry 

the same meaning and describe the same facilities. Exelon adds that drafting history 

confirms that the Reliability Standard drafting team intended this interpretation. 

73. We agree. In our view, “critical to the reliability of the bulk electric system” in 

PRC-023-1 and “operationally significant” in Recommendation 21A are intended to have 

the same meaning because PRC-023-1 was developed to implement Recommendation 

21A. This conclusion sheds some light on what facilities should be identified as “critical 

to the reliability of the bulk electric system” because, in Recommendation 21A, the Task 

Force listed lines that are part of monitored flowgates and interfaces as examples of 

79 Id. 

80 While the ERO is free to submit a modified Reliability Standard that adopts the 

guidance set forth below as the mandatory test, we will also consider “an equivalent 

alternative approach provided that the ERO demonstrates that the alternative will 

adequately address the Commission’s underlying concern or goal as efficiently and 

effectively as the Commission’s proposal” and is consistent with our guidance. Id. P 186. 
Docket No. RM08-13-000 - 50 - 

“operationally significant” facilities. Importantly, the Task Force did not recommend 

that NERC limit its extended review only to monitored flowgates and interfaces; it 

merely cited monitored flowgates and interfaces as examples of “operationally 

significant” facilities. If a facility trips on relay loadability following an initiating event 

and contributes to undesirable system performance similar to what occurred during the 

August 2003 blackout (e.g., cascading outages and loss of load) in the same way that the 

loss of monitored flowgates and interfaces contributed to the August 2003 blackout, the 

facility is operationally significant for the purposes of Recommendation 21A, and 

therefore critical to the reliability of the bulk electric system for the purposes of PRC023-1. For example, the 138 kV lines shown in Figure 5.12 of the Final Blackout Report 

were not part of the monitored flowgate of the 345 kV Sammis-Star line or any other 

flowgate in FirstEnergy, but the loss of these 138 kV facilities affected loading on 

Sammis-Star, and the loss of Sammis-Star was the point at which the blackout went into 

its dynamic cascading phase. Thus, we reject assertions, made in the context of 

comments on the “rule out” approach, that facilities that are not part of a defined and 

routinely monitored flowgate should automatically be excluded from the Reliability 

Standard’s scope. 

ii. Guidance on the Test

74. Neither the Final Blackout Report nor the Reliability Standard establishes a 

mandatory test for planning coordinators to use to determine if a facility is “operationally 
Docket No. RM08-13-000 - 51 - 

significant” or “critical to the reliability of the bulk electric system” with respect to relay 

settings and the prevention of cascading outages. However, in its comments on the 

NOPR, NERC includes the guidance for identifying operationally significant 100 kV-200 

kV facilities that the NERC System Protection and Control Task Force supplied to 

Regional Entities during the voluntary Beyond Zone 3 relay review and mitigation 

program. This guidance advised Regional Entities to identify: 

All circuits that are elements of flowgates in the Eastern Interconnection, 

Commercially Significant Constraints in the Texas Interconnection, or 

Rated Paths in the Western Interconnection. This includes both the 

monitored and outage element for OTDF sets. 

All circuits that are elements of system operating limits (SOLs) and 

interconnection reliability operating limits (IROLs), including both 

monitored and outage elements. 

All circuits that are directly related to off-site power supply to nuclear 

plants. Any circuit whose outage causes unacceptable voltages on the offsite power bus at a nuclear plant must be included, regardless of its 

proximity to the plant. 

All circuits of the first 5 limiting elements (monitored and outaged 

elements) for transfer interfaces determined by regional and interregional 

transmission reliability studies. If fewer than 5 limiting elements are found 

before reaching studied transfers, all should be listed. 

Other circuits determined and agreed to by the reliability 

authority/coordinator and the Regional Reliability Organizations. 

75. After careful review, we conclude that the guidance provided by the NERC 

System Protection and Control Task Force, if applied appropriately, would identify some, 

but likely not all, critical sub-200 kV facilities. There are some critical facilities that the 
Docket No. RM08-13-000 - 52 - 

 

guidance would not identify and would need to identify in order for it to be a fully 

acceptable test and meet the reliability objectives of PRC-023-1. 

76. In the Commission’s view, the NERC System Protection and Control Task Force 

guidance focuses primarily on identifying facilities that are “operationally significant” 

between regions (e.g., between ECAR and SERC) or between sub-regions (e.g., between 

Southern and Entergy) and would not necessarily identify operationally significant 

facilities within a sub-region or a company.81 In order to achieve its objective, however, 

PRC-023-1 must apply to relay settings on all operationally significant sub-200 kV 

facilities that could trip on relay loadability and contribute to cascading outages and the 

loss of load, including those within a sub-region or a company. The ERO could refine 

the NERC System Protection and Control Task Force’s guidance into an acceptable 

mandatory test by, among other things, revising it to include the assessment and 

identification of facilities within a region, sub-region, or company, whose inadvertent 

outage due to relay loadability could result in undesirable system performance.82 

81 We understand that some interregional studies include only a portion of all the 

lines with the remaining modeled as equivalents. Such an analysis could not possibly 

address the operational significance of the lines that were modeled only as equivalents. 

82 The ERO is not limited to proposing a revised version of the NERC System 

Protection and Control Task Force’s guidance as the mandatory test. It can also develop 

a new test to identify critical sub-200 kV facilities or refine other aspects of the System 

Protection and Control Task Force test. Any test that the ERO submits, including one 

based on the NERC System Protection and Control Task Force’s guidance, must be 

consistent with the general guidelines set forth in this Final Rule. 
Docket No. RM08-13-000 - 53 - 

77. The test for identifying operationally significant/critical sub-200 kV facilities 

should identify facilities that must have their relays set in accordance with PRC-023-1 to 

avoid the undesirable system performance that Recommendation 21A was intended to 

prevent. It should also describe the steady state and dynamic base cases that planning 

coordinators must use in their assessment. 

78. Recommendation 21A of the Final Blackout Report was developed to prevent 

undesirable system performance like the undesirable performance that occurred during 

the August 2003 blackout. During the blackout, the inadvertent tripping of facilities due 

to loadability resulted in undesirable system performance in the form of cascading 

outages and the loss of load. Since PRC-023-1 implements Final Blackout 

Recommendation No. 21A, it too must prevent the undesirable system performance that 

would include, among other performance factors, cascading outages and the loss of load. 

79. To achieve this goal, the test to determine which sub-200 kV facilities are subject 

to PRC-023-1 must include or be consistent with the system simulations and assessments 

that are required by the TPL Reliability Standards and meet the system performance 

levels for all Category of Contingencies used in transmission planning. As discussed in 

the NOPR, the Commission expects that the base cases used to determine the facilities 

subject to PRC-023-1 will include various generation dispatches, topologies, and 

maintenance outages assumed in the planning time frame, and will consider the effect of 
Docket No. RM08-13-000 - 54 - 

 

redundant and backup protection systems.83 As such, the base cases shall bracket all 

stable operating conditions. 

80. Thus, the ERO must develop a test that: (a) defines expectations of desirable 

system performance; and (b) describes the steady state and dynamic base cases that the 

planning coordinator must use in its assessments to carry out Requirement R3. The goal 

of the test must be consistent with the general reliability principles embedded in the 

existing series of TPL, Transmission Operations (TOP), Reliability Coordination (IRO), 

and Protection and Control (PRC) Reliability Standards. This is, in fact, good utility 

practice worldwide in that, if an initiating event84 results in inadvertent outage85 or the 

tripping of other non-faulted facilities that would result in cascading outages or loss of 

load, or violation of any of the applicable criteria, these facilities must be identified for 

83 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 43, n.71. A “base case” refers to the 

transmission system model used for performing planning studies. 

84 In power systems, an “initiating event” generally refers to any event on the 

electric system that begins a series of actions. For transmission planning purposes, an 

initiating event is usually modeled as a type of fault. A “fault” is defined in the NERC 

Glossary of Terms used in Reliability Standards as “[a]n event occurring on an electric 

system such as a short circuit, a broken wire, or an intermittent connection.” See NERC 

Glossary of Terms used in Reliability Standards at 7. 

85 An “inadvertent outage” generally refers to an unplanned outage of a facility. 

For the purposes of PRC-023-1, an inadvertent outage is the tripping of a facility due to 

loadability conditions. 
Docket No. RM08-13-000 - 55 - 

remedial actions (such as equipment modifications, or a reduction in IROLs or SOLs) to 

ensure Reliable Operation. We provide guidance on both features of the test below. 

iii. Desirable System Performance

81. During the August 2003 blackout, facilities (regardless of the voltage class and 

whether or not they were part of monitored flowgates) inadvertently tripped due to 

loadability conditions, resulting in undesirable system performance under the TPL 

Reliability Standards in the form of exceeding SOL and IROL limits, cascading outages, 

and the loss of load. Consequently, consistent with the TPL Reliability Standards, the 

first component of desirable system performance that the test must seek to maintain is the 

continuity of all firm load supply except for supply directly served by the faulted facility. 

In other words, it is the Commission’s view that the test must identify facilities necessary 

to achieve the reliability performance for Category B and Category C contingencies—

which would include no non-consequential load loss (for Category B) and no cascading 

outages (for Category B and Category C) for all stable operating conditions.86 

82. The TPL Reliability Standards address, among other things, the type of 

simulations and assessments that must be performed to ensure that reliable systems are 

 86 In Order No. 693, the Commission explained that the term “consequential load 

loss” refers to “load that is directly served by the elements that are removed from service 

as a result of the contingency.” Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1794, 

n.461. 
Docket No. RM08-13-000 - 56 - 

 

developed to meet present and future systems needs.87 Table 1 of the TPL Reliability 

Standards establishes the desired system performance requirements for a range of 

contingencies grouped according to the number of elements forced out of service as a 

result of the contingency. Consistent with Table 1 of the TPL Reliability Standards, with 

the exception of extreme contingency events, the system should always be stable and 

within both thermal and voltage limits for Reliable Operation.88 This is the second 

component of desirable system performance that the test must seek to determine. 

83. Finally, while the curtailment of firm transfers is permitted to prepare for the next 

contingency, it is generally not the desired system performance for single contingencies 

required by Table 1 of the TPL Reliability Standards. Thus, continuity of all firm 

transfers is the third component of desirable system performance.89 

84. In sum, because the Bulk-Power System is planned and operated as a minimum 

criterion to maintain Reliable Operation for the single contingency loss of any 

transmission facility,90 for Category B contingencies, desirable system performance 

87 Id. at P 1683. 

88 Extreme contingency events are the loss of two or more (multiple) elements 

(Category D). 

89 See Reliability Standard TPL-002-0. Footnote b of Table 1 allows for the 

interruption of firm load for consequential load loss. This footnote is currently the 

subject of an order setting a deadline for required revisions in RM06-16-009. 

90 Reliability Standard TOP-002-0, Normal Operations Planning, Requirement R6 

establishes that each balancing authority and transmission operator shall plan to meet 

(continued...) 
Docket No. RM08-13-000 - 57 - 

includes: (1) continuity of all firm load supply except for supply directly served by the 

faulted facility and no cascading outages; (2) the maintenance of all facilities within their 

applicable thermal, voltage, or stability ratings (short time ratings are applicable); and 

(3) the continuance of all firm transfers.91 For Category C contingencies, desirable 

system performance includes: (1) continuity of all firm load supply except for planned 

interruptions and no cascading outages; (2) the maintenance of all facilities within their 

applicable thermal, voltage, or stability ratings (short time ratings are applicable); and 

(3) the continuance of all firm transfers that are not part of planned interruptions.92 

iv. Steady State and Dynamic Base Cases

85. With respect to the steady state and dynamic base cases that planning coordinators 

must use as part of their assessments, the Commission stated in the NOPR that it expects 

planning coordinators to use base cases that include various generation dispatches, 

topologies, and maintenance outages, and that consider the effect of redundant and 

 

unscheduled changes in system configuration and generation dispatch (at a minimum N-1 

Contingency Planning) in accordance with NERC, Regional Reliability Organization, 

sub-regional, and local reliability requirements. 

91 See Reliability Standard TPL-002-0. Footnote b of Table 1 allows for the 

interruption of firm load for consequential load loss. 

92 See Reliability Standard TPL-003-0. Footnote c of Table 1 allows for the 

controlled interruption of electric supply to customers (load shedding), the planned 

removal from service of certain generators, and/or the curtailment of contracted Firm 

(non-recallable reserved) electric power transfers necessary to maintain the overall 

reliability of the interconnected transmission systems. 
Docket No. RM08-13-000 - 58 - 

 

backup protection systems. The Commission also stated that the process for identifying 

critical facilities must include the same system simulations and assessments as the TPL 

Reliability Standards for all stable operating conditions. The TPL Reliability Standards 

establish the types of simulations and assessments that must be performed to ensure that 

reliable systems are developed to meet present and future system needs. It is through 

these simulations and assessments that the planning authority and transmission planner 

demonstrate that their portion of the interconnected transmission system is planned for 

Reliable Operation under contingency conditions. In order to produce a “valid” 

assessment, the planning authority or transmission planner must demonstrate that its 

network can be operated to supply projected customer demands and projected firm 

transmission service, at all demand levels, over the range of forecast system demands, 

and under the contingency conditions defined in Table 1.93 The Commission understands 

that Category B contingencies would cover most of the primary relay applications and 

Category C contingencies would cover most of the backup and remote circuit breaker 

failure relay applications. However, if a portion of a system is expected to be operated 

differently than the minimal TPL base cases, additional base cases should be included to 

include all stable operating conditions. 

93 In order for a planning authority and transmission provider to produce a “valid” 

assessment, the assessment must be demonstrated as satisfying each of the criteria 

established in TPL-002-0 through TPL-004-0, Requirement R1. 
Docket No. RM08-13-000 - 59 - 

 

86. In addition to the TPL Reliability Standards, the TOP Reliability Standards are 

relevant to the steady state and dynamic base cases that reliability entities must use as 

part of their assessments. The TOP Reliability Standards establish, among other things, 

the responsibilities and decision-making authority for Reliable Operation in real-time. 

Reliability Standard TOP-002-0 establishes requirements for operation plans and 

procedures essential for Reliable Operation, including development of SOLs and IROLs 

that will result in acceptable system responses for unplanned events. 

87. At a minimum, the Bulk-Power System is planned and operated to maintain 

Reliable Operation for the single contingency loss of any transmission facility.94 

Consequently, the base cases that planning coordinators must use in their assessments for 

PRC-023-1 applicability should represent, at a minimum, the fundamental base case 

categories to plan for Reliable Operation and the real-time response for Reliable 

Operation. Fundamental base case categories may be more extensive than those that are 

central to meeting the performance requirements established in TPL-002-0, Requirement 

R1 if they do not include all reliable operating conditions. We believe that initiating 

events that represent all feasible types and locations of faults, including evolving faults, 

94 See Reliability Standard TPL-002-0, System Performance Following Loss of a 

Single BES Element. See also Reliability Standard TOP-002-0, Normal Operations 

Planning, Requirement R6 that establishes that each balancing authority and transmission 

operator shall plan to meet unscheduled changes in system configuration and generation 

dispatch (at a minimum N-1 Contingency Planning) in accordance with NERC, Regional 

Reliability Organization, sub-regional, and local reliability requirements. 
Docket No. RM08-13-000 - 60 - 

 

must be simulated in each of the fundamental base case categories to determine the 

performance of the system. This is necessary for PRC-023-1 applicability because any of 

these initiating events can occur and must be included in determining performance. It is 

also consistent with the development of valid transmission assessments required by the 

TPL Reliability Standards.95 Under this approach, a facility would be identified as a 

critical facility if, during a simulation starting with the base cases, its removal from 

service following an initiating event would prevent desirable system performance, as we 

have defined it here. 

88. With this in mind, base case categories in the application of a test to identify 

critical facilities must: 

(1) Represent the full range of demand and transfer levels. This is 

consistent with TPL-002-0, Requirement R1.3.5 (which requires that all 

projected firm transfers be modeled) and TPL-002-1, Requirement R1.3.6. 

(which requires that all studies and simulations be performed and evaluated 

for selected demand levels over the range of forecast system demands); 

(2) Include all stable operating conditions and allowable topologies, such 

as all allowable planned outages. This is consistent with TPL-002-0, 

Requirement R1.3.12. (which requires that the planned (including 

95 See Order No. 693, FERC Stats. & Regs. ¶ 32,642 at P 1683. 
Docket No. RM08-13-000 - 61 - 

maintenance) outage of any bulk electric equipment (including protection 

systems or their components) be included at those demand levels for which 

planned (including maintenance) outages are performed); and TOP-004 

Requirement R4 (which requires operating the actual system in a known 

operating state). 

(3) Include the effects of the protection system design and settings of the as 

designed protection systems with identification of those that are not within 

the Requirements of PRC-023-1. This is consistent with TPL-002-0, 

Requirement R1.3.8 with regard to existing and planned protection 

systems; 

(4) Include the effects of the failure of a single component within the as 

designed Protection Systems, consistent with TPL-002-0 Requirement 

R1.3.10, but with regard to backup and redundant protection systems; and 

(5) Include various generation dispatch patterns. This is consistent with 

TOP-002-0 Requirement R6 (which requires that each balancing authority 

and transmission operator plan to meet unscheduled changes in system 

configuration and generation dispatch (at a minimum N-1 contingency 

planning) in accordance with NERC, Regional Reliability Organization, 

sub-regional and local reliability requirements). 
Docket No. RM08-13-000 - 62 - 

89. Our guidance above for developing a test to determine operationally significant 

facilities that should be subject to PRC-023-1 is consistent with Recommendation 

No. 21A of the Final Blackout Report and with planning and operating practices for 

Reliable Operation of the Bulk-Power System. Using a flowgate as an example, to derive 

the IROL of a given flowgate under a given range of system conditions, the TOP 

operations planner, in carrying out day-ahead reliability assessments, would simulate 

contingencies on critical facilities at a given loading on the flowgate, proceeding through 

the list of all critical and operationally significant facilities that form the monitored 

flowgates or other facilities as determined to be applicable, either by actual simulation 

tests or engineering judgment, to eliminate the less critical facilities that are not binding 

to the IROL and facilities that are not part of that flowgate. The derived IROLs would be 

valid only if none of the remaining flowgate facilities inadvertently trip with the binding 

facility or facilities on which the contingency is applied. Similarly, for the purposes of 

the test described above, the facilities that are not “operationally significant,” and 

therefore can be excluded from PRC-023-1, would be those that trip due to loadability 

conditions at the same time as an initiating event involving a critical or operationally 

significant facility but do not impede desirable system performance. 

90. For the particular flowgate under analysis by the TOP operations planner, the 

limiting facilities are those that result in the lowest IROL, and thus are commonly 

referred to as critical facilities. All the remaining flowgate facilities and other facilities 
Docket No. RM08-13-000 - 63 - 

that are not part of the flowgate under analysis are operationally significant for two main 

conditions: (i) following a contingency on a binding or critical facility, they will not trip 

inadvertently and result in an increase in the loadings on other facilities and/or stable 

power swings that could result in additional trips, thereby invalidating the derived 

IROL;96 and (ii) the outage of these operationally significant facilities would reduce the 

IROL since the flowgate would have one less element before a contingency on the critical 

facility is applied. Similar analysis would be conducted for other facilities that are not 

part of a flowgate. 

v. Response to Relevant Comments

91. The Commission received comments pertaining to its statements about the process 

for identifying critical 100 kV-200 kV facilities and its proposal to permit case-by-case 

exceptions for the limited number of facilities that are not critical to the reliability of the 

bulk electric system and that would not result in cascading outages, instability, 

uncontrolled separation, violation of facility ratings, or interruption of firm transmission 

service.97 While some comments are no longer relevant given the Commission’s 

decision not to adopt the “rule out” approach, others bear on how to understand the 

 96 In Order No. 693, the Commission explained that “[i]n deriving SOLs and 

IROLs. . . the functions, settings, and limitations of protection systems are recognized 

and integrated.” Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1435. 

97 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 43. 
Docket No. RM08-13-000 - 64 - 

 

designation “critical to the reliability of the bulk electric system” in the context of 

Requirement R3. 

92. For example, APPA argues that the Commission should allow some diversity in 

regional definitions of critical facilities to account for physical differences in network 

topology, design, and performance. To this end, APPA proposes that the Commission 

direct NERC to develop a process whereby each region can develop a common regionwide approach to identifying critical facilities.98 We believe that the test set forth above 

is best implemented uniformly across all regions. We direct a uniform approach rather 

than the one suggested by APPA because, as NERC comments in its petition, the effects 

of PRC-023-1 are not constrained to regional boundaries.99 Any test to identify critical 

facilities must be consistent across regions so that the effects of protective relay operation 

are consistent across regions. 

93. Duke comments that application of the existing TPL standards to its Midwest and 

Carolina systems has not identified any sub-200 kV facilities as critical (i.e., there have 

been no showings that the loss of any such facilities could result in cascading outages, 

instability, or uncontrolled separation).100 As we have explained, however, the test that 

(continued...) 

98 APPA at 17, 26-27. 

99 NERC Petition at 18-19, 39-41. 

100 Duke adds that potential revisions to the TPL Reliability Standards appear as 

though they will raise the bar in clarifying the requirements for firm transmission service 
Docket No. RM08-13-000 - 65 - 

 

would be developed by the ERO and that would adhere to the guidance we provide in this 

Final Rule would take into consideration both the desired system performance that 

PRC-023-1 was developed to achieve and the desired system performance required by the 

TPL Reliability Standards for Reliable Operation. 

94. We also note that some commenters argue that the Reliability Standard should not 

apply to radial transmission lines and Category D Contingencies. With regard to radial 

transmission lines, we note that the NERC definition of “bulk electric system” does not 

include radial transmission facilities serving load with only one transmission source. We 

reiterate that we do not intend to expand the applicability of PRC-023-1 beyond NERC’s 

Statement of Registry Criteria. 

95. Additionally, we do not conclude that the applicability of PRC-023-1 should be 

determined based on Category D contingencies (pursuant to Table I of the TPL 

Reliability Standards). We understand that relay settings can not be determined with 

great certainty for extreme multi-contingency conditions—the types of conditions 

consistent with the Category D contingencies of the TPL Reliability Standards. In fact, 

Reliability Standard TPL-004-0 requires that the planning authority and transmission 

planner demonstrate through a valid assessment and documentation that their portion of 

(i.e., it appears that there will be more restrictions on loss of local load that is not 

connected to a faulted system element), but are unlikely to result in many facilities under 

200 kV being considered critical to bulk electric system reliability. 
Docket No. RM08-13-000 - 66 - 

the interconnected electric system is evaluated only for the risks and consequences of 

such events. 

96. Some commenters argue that violation of facility ratings and interruption of firm 

transmission service should not be part of the applicability test. We are not persuaded by 

this argument because, as previously discussed, these are included in the three reliability 

components of desirable system performance. 

97. Finally, commenters argue that there should be some mechanism for entities to 

challenge criticality determinations. We agree that such a mechanism is appropriate and 

direct the ERO to develop an appeals process (or point to a process in its existing 

procedures) and submit it to the Commission no later than one year after the date of this 

Final Rule. 

D. Generator Step-Up and Auxiliary Transformers

 1. Omission from the Reliability Standard

98. NERC stated that generator step-up transformer relay loadability was intentionally 

omitted from PRC-023-1 and would be addressed in a future Reliability Standard.101

 101 The Commission notes that in its comments NERC refers to “generator relay 

loadabilty.” In the context of our determination, we understand “generator step-up and 

auxiliary transformer loadability” and “generator relay loadability” to refer to the same 

thing. 
Docket No. RM08-13-000 - 67 - 

a. NOPR Proposal

99. In the NOPR, the Commission stated that the ERO must address generator step-up 

and auxiliary transformer relay loadability in a timely manner and proposed directing the 

ERO to modify PRC-023-1 to include these issues. The Commission also requested 

comments suggesting a reasonable time frame for the ERO to either modify PRC-023-1 

to address generator step-up and auxiliary transformer relay loadability or to develop a 

new Reliability Standard addressing these issues. 

b. Comments

100. NERC states that within two years it expects to submit to the Commission a 

Reliability Standard that addresses generator relay loadability. NERC explains that a 

team under the NERC System Protection and Control Subcommittee is working with the 

Institute of Electrical and Electronics Engineers (IEEE) Power System Relay Committee 

on a technical reference document (Power Plant and Transmission System Protection and 

Coordination) that addresses transmission protection coordination with generation 

protection systems, provides technical guidance for the revision of PRC-001,102 and 

includes technically based loadability requirements.103 NERC adds that generator relay 

 102 The purpose of PRC-001 is to ensure that system protection is coordinated 

among operating entities. 

103 NERC presented a draft of the technical reference document at its September 

2009 meeting. 
Docket No. RM08-13-000 - 68 - 

loadability is just a single facet of the total system protection coordination requirement 

between generators and transmission lines, and recommends that all coordination issues 

between generators and transmission lines, including generator step-up and auxiliary 

transformer relay loadability, reside in PRC-001-2. 

101. Many commenters agree that generator step-up and auxiliary transformer relay 

loadability must be addressed in a timely manner, but in a separate Reliability Standard 

from PRC-023-1. In general, these commenters argue that properly addressing generator 

step-up and auxiliary transformer relay loadability requires in-depth technical analysis 

and careful consideration of related protection and coordination issues and should not be 

rushed to accommodate PRC-023-1. 

102. Entergy argues that the NOPR appears to treat generator step-up and auxiliary 

transformers as transmission-related facilities, contrary to the Commission’s ratemaking 

precedent. Entergy explains that generator step-up and auxiliary transformers are not 

transmission facilities, and that their function is to connect generation capacity to the 

transmission grid at appropriate voltage levels. Entergy adds that when generation is offline, neither generator step-up transformers nor auxiliary transformers are required for 

transmission throughput. 

103. The PSEG Companies argue that developing generator step-up and auxiliary 

transformer loadability requirements requires a significant effort by NERC and 

generation companies, and once developed, may require generation companies to conduct 
Docket No. RM08-13-000 - 69 - 

specific engineering studies for each of their generator step-up transformers. The PSEG 

Companies suggest that the Commission direct NERC to consider whether it can 

establish and determine a generic rating percentage. 

c. Commission Determination

104. We decline to adopt the NOPR proposal and will not direct the ERO to modify 

PRC-023-1 to address generator step-up and auxiliary transformer loadability. After 

further consideration, we conclude that it does not matter if generator step-up and 

auxiliary transformer loadability is addressed in a separate Reliability Standard, so long 

as the ERO addresses the issue in a timely manner and in a way that is coordinated with 

the Requirements and expected outcomes of PRC-023-1. 

105. In light of the ERO’s statement that within two years it expects to submit to the 

Commission a proposed Reliability Standard addressing generator relay loadability, we 

direct the ERO to submit to the Commission an updated and specific timeline explaining 

when it expects to develop and submit this proposed Standard. While we recognize that 

generator relay loadability is a complex issue that presents different challenges than 

transmission relay loadability, we note that more than six years have passed since the 

August 2003 blackout and there is still no Reliability Standard that addresses generator 

relay loadability. With this in mind, the Commission will not hesitate to direct the 

development of a new Reliability Standard if the ERO fails to propose a Standard in a 

timely manner. While the ERO is developing a technical reference document to facilitate 
Docket No. RM08-13-000 - 70 - 

the development of a Reliability Standard for generator protection systems, only 

Reliability Standards create enforceable obligations under section 215 of the FPA. 

106. We also expect that the ERO will develop the Reliability Standard addressing 

generator relay loadability as a new Standard, with its own individual timeline, and not as 

a revision to an existing Standard. While we agree that PRC-001-1 requires, among other 

things, the coordination of generator and transmission protection systems, we think that 

generator relay loadability, like transmission relay loadability, should be addressed in its 

own Reliability Standard if it is not to be addressed with transmission relay loadability. 

107. Additionally, although we do not adopt the NOPR proposal, we reject Entergy’s 

claim that including generator and transmission relay loadability in the same Reliability 

Standard would conflict with how the Commission treats generator step-up transformers 

for the purposes of ratemaking. The Commission’s primary objectives in ratemaking 

differ from its central objectives concerning reliability regulation. In the ratemaking 

context, the Commission is concerned that jurisdictional generator step-up and auxiliary 

transformers are classified in a way that ensures just and reasonable rates. In the 

reliability context, addressing transmission and generator relay loadability in the same 

Reliability Standard facilitates the reliability goal of ensuring coordination between 

transmission and generator protection systems, as required by PRC-001-1. 

108. Finally, the PSEG Companies suggest that the ERO consider whether a generic 

rating percentage can be established for generator step-up transformers and, if so, 
Docket No. RM08-13-000 - 71 - 

determine that percentage. Although we do not adopt the NOPR proposal, we encourage 

the ERO to consider the PSEG Companies’ suggestion in developing a Reliability 

Standard that addresses generator relay loadability. 

2. Generator Step-Up Transformer Relays as Back-Up Protection

a. Commission’s Statements in the NOPR

109. In describing PRC-023-1 in the NOPR, the Commission emphasized that: 

[T]he requirements of PRC-023-1 apply to all protection systems as 

described in Attachment A that provide protection to the facilities defined 

in sections 4.1.1 through 4.1.4 of PRC-023-1, regardless of whether the 

protection systems provide primary or backup protection and regardless of 

their physical location. . . . For example, a protective relay physically 

installed on the low-voltage side of a generator step-up transformer with the 

purpose of providing backup protection to a transmission line operated 

above 200 kV must be set in accordance with the requirements of PRC023-1 because it is applied to protect a facility defined in [] PRC-023-1.104

 b. Comments

110. EPSA and Ontario Generation disagree with the Commission’s statements and 

argue that the Commission’s example contains an error. Ontario Generation asserts that 

protective relaying that does not directly sense a current flow on a particular transmission 

circuit cannot affect its loadability. In that respect, Ontario Generation argues that the 

Reliability Standard’s existing requirements correctly refer to protection systems at 

specific circuit terminals. 

 104 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 33 (emphasis added). 
Docket No. RM08-13-000 - 72 - 

111. EPSA and Ontario Generation also challenge the Commission’s implication that 

generator step-up transformer relays are subject to the Reliability Standard if their 

purpose is to provide backup protection to transmission lines. The commenters assert 

that because phase fault back-up protection on the low voltage side of a generator step-up 

transformer is designed to detect un-cleared faults on the system, with the primary 

function of protecting the generator and the transformer from supplying a prolonged fault 

current, the relays discussed by the Commission are set pursuant to IEEE Standard 

C37.102 instead of PRC-023-1. 

c. Commission Determination

112. We reiterate that the requirements of PRC-023-1 apply to all protection systems as 

described in Attachment A that are intended to provide protection to the facilities defined 

in section 4.1.1 through 4.1.4 of the Reliability Standard, regardless of whether the 

protection systems provide primary or backup protection and regardless of their physical 

location. Our interpretation is based on the fact that protective relays are applied to 

protect specific system elements and, it is consistent with approved Reliability 
Docket No. RM08-13-000 - 73 - 

stems.107 

 

Standards,105 the zones of protection principle on which relaying schemes are 

designed,106 and NERC’s voluntary Beyond Zone 3 Review, which examined all primary 

and backup protection sy

113. We also clarify that protective relays can be applied as back-up protection in two 

different ways: they can be physically located at the generator terminal on the lowvoltage side of a generator step-up transformer and provide backup protection for a BulkPower System element (i.e., for a transmission line outside of the generator zone of 

protection), as discussed in the NOPR, or provide back-up protection for the generator 

and the step-up transformer (i.e., within the generator zone of protection), as the 

commenters discuss. In this Reliability Standard, the Commission is referring to the first 

type of relays; i.e. relays that are applied to provide back-up protection to Bulk-Power 

System elements and that would sense increased current flow due to a fault on a BulkPower System transmission circuit. In the NOPR, the Commission explained that 

105 See, e.g., Reliability Standard PRC-001-1, Requirement R1 (requiring that 

“[e]ach Transmission Operator, Balancing Authority, and Generator Operator shall be 

familiar with the purpose and limitations of protection system schemes applied in its 

area” (emphasis added)). 

106 Protective relays are applied to protect specific elements within its zone of 

protection on the electric system. The “zone of protection” principle is used to ensure 

that each element on the electric system is provided, at most primary, and at least backup, 

protection so that there are no unprotected areas. 

107 NERC Comments at 13. 
Docket No. RM08-13-000 - 74 - 

 

distance relays physically located at the generator terminal that are applied to protect 

Bulk-Power System facilities must be coordinated with primary protection systems for a 

transmission line and be set to see through108 the step-up transformer, providing backup 

protection for un-cleared faults on the Bulk-Power System. Consequently, these relays 

will sense increased current flow and may trip on high load and therefore must also be set 

pursuant to PRC-023-1. If the primary protection system of the transmission line fails to 

operate, or does not operate within a certain time, the backup protection operates and 

trips Bulk-Power System elements that it is applied to protect. 

114. Our statement that such relays are subject to the Reliability Standard is not in 

conflict with the use of a protection system to protect the generator/step-up transformer in 

the context of other industry standards, such as IEEE Standard C37.102,109 or with the 

exclusion in section 3.4 of Attachment A to PRC-023-1 of generator relays that are 

susceptible to load. The relays that we referred to in the NOPR, while they may be 

physically located at the generator terminal or on the low-voltage side of the generator 

step-up transformer, are applied to provide backup protection for Bulk-Power System 

108 To “see through” refers to a protective relay setting where, based on the 

apparent impedance as measured by the relay, the relay will detect faults beyond, i.e., 

“see through,” a bulk electric system element. 

109 IEEE Standard C37.102 (IEEE Guide for AC Generator Protection) provides 

generally accepted forms of relay protection applied to protect the synchronous generator 

and its excitation system. 
Docket No. RM08-13-000 - 75 - 

elements. This application is different from “generator relays,” which are also physically 

located at the generator, but are applied to protect the generator. 

E. Need to Address Additional Issues

115. In the NOPR, the Commission identified two additional issues that the ERO must 

address to ensure Reliable Operation of the Bulk-Power System: (1) zone 3/zone 2 relays 

applied as remote circuit breaker failure and backup protection; and (2) protective relays 

operating unnecessarily due to stable power swings. 

1. Zone 3/Zone 2 Relays Applied as Remote Circuit Breaker 

Failure and Back-Up Protection

 a. NOPR Proposal

116. In the NOPR, the Commission expressed concern about the impact that zone 

3/zone 2 relays applied as remote circuit breaker failure and backup protection can have 

on reliability when they operate without a time delay or for non-fault conditions. The 

Commission explained that if a zone 3/zone 2 relay detects a fault on an adjacent 

transmission line within its reach, and the relay on the faulted line fails to operate, the 

zone 3/zone 2 relay will operate as a backup and remove the fault; when it does, however, 

it will disconnect both the faulted transmission line and “healthy” facilities that should 

have remained in service. The Commission noted that zone 3/zone 2 relays are typically 
Docket No. RM08-13-000 - 76 - 

 

set to operate after a time delay in order to ensure coordination of protection and avoid 

unnecessarily disconnecting “healthy” facilities.110 

117. The Commission also explained that the large reach of a zone 3/zone 2 relay 

makes it susceptible to operating for certain non-fault conditions, such as very high 

loading and large, but stable power swings, because the current and voltage as measured 

by the impedance relay may fall within the very large magnitude and phase setting of the 

relay.111 The Commission cited the Task Force’s finding that fourteen 345 kV and 

138 kV transmission lines disconnected during the August 2003 blackout because of zone 

3/zone 2 relays applied as remote circuit breaker failure and backup protection,112

including several zone 2 relays in Michigan that overreached their protected lines by 

more than 200 percent and operated without a time delay.113 The Commission noted that 

while these relays operated according to their settings, the Task Force concluded that they 

operated so quickly that they impeded the natural ability of the electric system to hold 

together and did not allow time for operators to try to stop the cascade.114

110 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 50. 

111 Id. P 52. 

112 Final Blackout Report at 80. 

113 Id. 

114 Id. 
Docket No. RM08-13-000 - 77 - 

118. The Commission acknowledged NERC’s claim that PRC-023-1 is silent on the 

application of zone 3/zone 2 relays as remote circuit breaker failure and backup 

protection because it establishes requirements for any load-responsive relay regardless of 

its protective function.115 Nevertheless, given the Task Force’s conclusions about the 

role of zone 3/zone 2 relays in the August 2003 blackout, the Commission proposed to 

direct the ERO to develop a maximum allowable reach for zone 3/zone 2 relays applied 

as remote circuit breaker failure and backup protection.116 

b. Comments

119. NERC and other commenters argue that PRC-023-1 already addresses the 

Commission’s concerns because it establishes loadability limits based on protectionzone-specific limitations, such as equipment thermal ratings and maximum power 

transfer capability, for all load responsive relays, independent of their application.117 

120. EEI states that an entity will first develop protective relay settings that ensure 

adequate protection of its facility or facilities and then apply Requirement R1. EEI states 

that if the entity cannot satisfy Requirement R1, it must change its relay scheme to 

 115 See NERC Petition at 38-39. 

116 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 53. 

117 See Consumers Energy, Dominion, Duke, Entergy, Exelon, EEI, Oncor, 

PG&E, SCEG, Southern, TAPS. 
Docket No. RM08-13-000 - 78 - 

 

accommodate the need for protection and to comply with PRC-023-1.118 EEI maintains 

that Requirement R1 addresses the Commission’s concern in the NOPR because no 

exemption is given to relays that are set to cover adjacent lines in the event of breaker 

failure. EEI contends, therefore, that PRC-023-1 does not need to identify any maximum 

reach allowable outside of the impact on loadability. EEI further argues that issues of 

protective relay settings that over reach adjacent lines and trip with insufficient delay are 

coordination issues and not transmission relay loadability issues. EEI adds that, if remote 

back-up relays cannot provide adequate breaker failure coverage and still comply with 

PRC-023-1, then local breaker failure relaying must be applied.119 

121. BPA explains that by complying with one of the sub-requirements in Requirement 

R1 (R1.1 through R1.13), entities’ zone 3/zone 2 relay settings will be based on the real 

load carrying requirements of the line to which they are applied, but will not operate for 

allowable line loads. BPA argues that a blanket maximum reach limit would nullify the 

thirteen sub-requirements in Requirement R1, prevent entities from optimizing their relay 

settings for each situation, and unnecessarily reduce protection. Exelon states that 

PRC-023-1 allows entities to assess their relays’ loadability based on the most severe line 

ratings at severely depressed voltage, and either includes a margin beyond these ratings 

118 EEI at 19. 

119 Id. at 20. 
Docket No. RM08-13-000 - 79 - 

h 

 

or is based on the ability of a circuit to actually carry a load given its length and/or 

location within the system. Entergy asserts that maximum reaches are affected by the 

inherent capabilities of the relays, such as where load encroachment is present. 

122. ATC argues that the Commission’s proposal may put an arbitrarily low loading 

limit on some transmission lines. ATC explains that on a short transmission line, a relay 

setting of several times the line’s impedance would not limit the loading of the line, 

whereas on a long transmission line the same impedance setting would limit loading. 

ATC argues that a maximum allowable reach is immaterial because the security of a 

relay’s setting is determined by the relay’s load-sensitive trip point, together with an 

appropriate load margin with respect to the maximum load carrying capability of the 

protected transmission system element. 

123. WECC maintains that the appropriate use of readily available technology will 

completely addresses the Commission’s concerns. WECC observes that the relay 

operations identified by the Task Force and referenced by the Commission occurred 

mostly with relays that used traditional mho circle characteristics.120 WECC explains 

that the mho relay characteristic always includes a substantial resistive reach (in the 

direction of load, at least half the reactive reach) along with the necessary reactive reac

(in the direction of possible faults). WECC states that in modern microprocessor-based 

120 “Mho-circle” refers to the circular operating characteristic of a phase distance 

protection relay. 
Docket No. RM08-13-000 - 80 - 

ic load 

relays, several different methods are available to limit the relays’ resistive (load) reach 

without sacrificing the ability to detect remote faults (reactive reach), including noncircular characteristic shapes (e.g., lens, rectangle), offset mho, blinders, and specif

encroachment elements. 

124. Many commenters, including NERC, assert that establishing a shorter maximum 

reach for zone 3/zone 2 relays applied as remote circuit breaker failure and backup 

protection may adversely impact reliability. In general, these commenters assert that 

when the level of backup protection is reduced, there is an increased probability that 

faults will not be cleared and system stability will suffer. 

125. Commenters also stress the problems associated with setting a uniform maximum 

reach. Southern states that it would be difficult to establish an arbitrary maximum reach 

that fits all system configurations because the setting for a zone 3/zone 2 relay is based on 

the location of the relevant relay and the structure of the protection scheme for the 

pertinent system. Duke argues that an arbitrary relay reach limit would not provide the 

necessary protection flexibility to align protection needs with all primary system 

configurations and electrical characteristics. EEI and ITC argue that it is not technically 

possible with current system configurations to enact the Commission’s proposal and 

maintain reliability and ensure fault detection. EEI states that the electric industry’s 

technically preferred approach is to set specific fault conditions. 
Docket No. RM08-13-000 - 81 - 

126. The PSEG Companies speculate that the Commission’s proposal will translate into 

a requirement to replace zone 3 relays with expensive communication-based schemes. 

The PSEG Companies state that such a requirement would be impractical and ineffective 

with respect to facilities below 200 kV. Nevertheless, the PSEG Companies support 

limits on the reach of zone 3/zone 2 relays for circuits that are truly critical, provided that 

the circuits are identified through an open process and their designation supported by a 

proper engineering analysis by the Regional Entity. 

c. Commission Determination

127. We decline to adopt the NOPR proposal and will not direct the ERO to develop a 

maximum zone 3/zone 2 reach. After further consideration, we agree with commenters, 

especially NERC and EEI, that PRC-023-1, which interacts with existing FAC, IRO, and 

TOP Reliability Standards while ensuring adequate circuit breaker failure protection, 

sufficiently addresses the Commission’s concern. 

128. In its petition, NERC stated that the interactions between PRC-023-1 and existing 

FAC, IRO, and TOP Reliability Standards require entities and operators to establish 

limits for all system elements, operate interconnected systems within these limits, take 

immediate action to mitigate operation outside these limits, and set protective relays to 

refrain from operating until the observed condition on their protected element exceeds 
Docket No. RM08-13-000 - 82 - 

 

these limits.121 EEI maintains that Requirement R1 addresses the Commission’s concern 

because no exemption is given to relays that are set to cover adjacent lines in the event of 

breaker failure. EEI contends, therefore, that PRC-023-1 does not need to identify any 

maximum reach allowable outside of the impact on loadability. EEI adds that, if remote 

back-up relays cannot provide adequate breaker failure coverage and still comply with 

PRC-023-1, then local breaker failure relaying must be applied. 

129. We agree with NERC and EEI that if an entity chooses to use remote breaker 

failure protection, it must comply with PRC-023-1 and its protection settings, derived 

pursuant to PRC-023-1, must interact with other relevant Reliability Standards to ensure 

Reliable Operation. EEI asserts that if remote backup relays cannot provide adequate 

breaker failure coverage and still comply with PRC-023-1, then local breaker failure 

relaying must be applied. We agree. This assertion addresses our concern that entities 

would continue to rely on the use of remote breaker failure protection and simply comply 

with PRC-023-1 without ensuring whether: (i) it provides adequate circuit breaker failure 

protection coverage; and (ii) that the limitation of remote circuit breaker failure 

protection and the settings so derived to comply with PRC-023-1 are reflected in the 

derivation of IROLs and SOLs that are used in real time operations. 

 

121 NERC Petition at 15-16. 
Docket No. RM08-13-000 - 83 - 

2. Protective Relays Operating Unnecessarily Due to Stable Power 

Swings

130. In the NOPR, the Commission stated that the cascade during the August 2003 

blackout was accelerated by zone 3/zone 2 relays that operated because they could not 

distinguish between a dynamic, but stable power swing and an actual fault. The 

Commission observed that PRC-023-1 does not address stable power swings, and pointed 

out that currently available protection applications and relays, such as pilot wire 

differential, phase comparison and blinder-blocking applications and relays, and 

impedance relays with non-circular operating characteristics, are demonstrably less 

susceptible to operating unnecessarily because of stable power swings. Given the 

availability of alternatives, the Commission stated that the use of protective relay systems 

that cannot differentiate between faults and stable power swings constitutes miscoordination of the protection system and is inconsistent with entities’ obligations under 

existing Reliability Standards. The Commission explained that a protective relay system 

that cannot refrain from operating under non-fault conditions because of a technological 

impediment is unable to achieve the performance required for Reliable Operation. 

Consequently, the Commission requested comments on whether it should direct the ERO 

to develop a new Reliability Standard or a modification to PRC-023-1 that requires the 
Docket No. RM08-13-000 - 84 - 

use of protective relay systems that can differentiate between faults and stable power 

swings and phases out protective relay systems that cannot meet this requirement.122

a. Comments

131. NERC opposes addressing stable power swings in a modification to PRC-023-1. 

NERC argues that while it is possible to employ protection systems that are immune from 

stable power swings, the Commission should not require the use of these systems at the 

expense of diminishing the ability of protective relays to dependably trip for faults or 

detect unstable power swings. According to NERC, there are two ways to prevent 

protective relays from operating during stable power swings: (1) select a protection 

system that will differentiate between faults and stable power swings, but will not trip for 

any power swing, such as current differential or phase comparison; or (2) utilize an 

impedance-based protection system that relies on careful selection of the protective relay 

trip characteristic, including shape (e.g., mho circle, lens) and sensitivity, to differentiate 

between faults, stable swings, and unstable swings. NERC adds that selection of the trip 

characteristic requires coordination based on fault coordination and transient stability 

studies between the protection system designer and the transmission planner. 

132. While NERC acknowledges that PRC-023-1 is designed to address the steadystate aspects of relay loadability, it also claims that PRC-023-1 has positive effects in 

 122 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 60. 
Docket No. RM08-13-000 - 85 - 

 

relation to relays and stable power swings. Specifically, the modifications required by 

PRC-023-1 to increase steady state loadability necessarily decrease the likelihood that 

relays will trip on stable power swings. 

133. NERC cautions that it must carefully study and analyze the relationship between 

stable power swings and protective relays, and consult with IEEE and other organizations 

before developing a Reliability Standard addressing stable power swings. NERC 

requests that the Commission allow PRC-023-1 to remain focused on steady state relay 

loadability and leave stable power swings to be specifically addressed in a different 

Reliability Standard. 

134. Other commenters agree with the concerns identified by the Commission. None, 

however, think that the Commission should direct the ERO to modify PRC-023-1 to 

address stable power swings.123 Many commenters agree with NERC and urge the 

Commission to allow the ERO to address stable power swings in a different Reliability 

Standard, after the ERO has had the opportunity to further study the issue. EEI and 

Southern argue that PRC-023-1 addresses the steady-state aspects of relay loadability, not 

transient system conditions such as stable or unstable power swings. The PSEG 

Companies reflect the view of many commenters when they argue that issues related to 

stable power swings are too complex to be addressed in PRC-023-1. Dominion adds that 

123 See, e.g., EEI; APPA; PG&E; ATC; Ameren; BPA; Duke; Oncor; and TAPS. 
Docket No. RM08-13-000 - 86 - 

if the Commission did direct the ERO to address stable power swings in PRC-023-1, the 

final implementation of the Reliability Standard would be significantly delayed. TAPS 

argues that the Commission should give due weight to NERC’s decision not to address 

stable power swings in PRC-023-1. APPA asserts that the Commission can require only 

that the ERO examine the Commission’s concerns about stable power swings and cannot 

direct the ERO to implement a specific solution. 

135. Several commenters challenge the Commission’s reasoning and assumptions in 

the NOPR. Exelon challenges the Commission’s assertion that a protective relay system 

that cannot refrain from operating under non-fault conditions because of a technological 

impediment is unable to achieve the performance required for reliable operation, arguing 

that it ignores many years of reliable and stable operation of mho-circle relays. Exelon 

adds that it is unaware of any instance in the entire history of its ComEd or PECO 

operating companies when mho-type distance relays tripped because of a stable power 

swing, and that none of its stability studies have ever identified lines that would trip on a 

stable power swing. 

136. ElectriCities, the MDEA Cities, and the Six California Cities challenge the 

Commission’s assertion that the use of protective relays that cannot differentiate between 

faults and stable power swings is mis-coordination of the protection system and is 

inconsistent with an entity’s obligations under existing Reliability Standards. In their 

view, the Commission should not use this proceeding to interpret existing Reliability 
Docket No. RM08-13-000 - 87 - 

 

Standards to require the use of specific protection technologies and proscribe the use of 

others; ElectriCities asserts that interpreting Reliability Standards not at issue may violate 

the Administrative Procedure Act.124

137. Consumers Energy disagrees with the Commission’s assertion that stable power 

swings contributed to the cascade in the August 2003 blackout. Consumers Energy states 

that it extensively studied the events discussed in the NOPR and concluded that 

communications-based relay systems operated because of the extremely heavy reactive 

power consumption of the lines, not stable power swings. Consumers Energy states that 

its studies also show that relay systems designed to be less susceptible to stable power 

swings would still have operated under these conditions, as the extreme reactive power 

consumption appeared to both terminals of each line as an internal fault. 

138. WECC claims that PRC-023-1 provides indirect, but highly effective protection 

against stable power swings. WECC asserts that the real problem that occurred during 

the August 2003 blackout was that zone 3/zone 2 relays operated and disconnected 

facilities because of high loading. WECC argues that if those zone 3/zone 2 trips had 

been prevented, significant system oscillations would not have occurred and “healthy” 

transmission lines would not have unnecessarily tripped. WECC asserts that PRC-023-1 

is specifically designed to prevent zone 3/zone 2 trips due to high loading. EEI argues 

124 5 U.S.C. 551, et seq. 
Docket No. RM08-13-000 - 88 - 

that PRC-023-1 is “well suited” to prevent the unnecessary operation of relays during 

stable power swings because as relay loadability is increased, the proper response to 

stable power swings is enhanced. 

139. Several commenters challenge the Commission’s assumption that preventing 

relays from operating due to stable power swings will improve reliability. TAPS explains 

that an important secondary function of protective relaying is protecting equipment and 

safety in the event of multiple or extreme contingencies. TAPS states that the power 

system is operated to account for single and double contingencies, but that extreme 

contingencies can occur and overload facilities to well beyond their emergency ratings. 

TAPS contends that it is impractical to rely on operators to manually operate the system 

beyond single and double contingencies, so automatic equipment is needed to protect the 

system when extreme contingencies occur. TAPS maintains that while 

impedance/distance relays are susceptible to operating for stable power swings, they are 

often the only protection for facilities loaded beyond emergency ratings. TAPS argues 

that the Commission’s proposal would reduce reliability because it would expose the 

system to longer-term outages due to equipment damage. TAPS also claims that 

overloading due to multiple or extreme contingencies can create the same safety issues 

the Commission discussed in the NOPR with respect to sub-requirement R1.10. 

140. E.ON argues that the Commission may have elevated the operational reliability of 

the bulk electric system over public safety and the transmission asset owner’s interest in 
Docket No. RM08-13-000 - 89 - 

ensuring that its assets remain in working order and available for service. E.ON explains 

that relay settings must ensure the maintenance of minimum vertical safety clearances, 

and that modifying relaying schemes to accommodate non-fault related transient 

overloads might leave system elements exposed to excessive loading longer than is 

prudent. E.ON further explains that because transmission facilities are located in diverse 

environments, it is appropriate to maintain a specified vertical line clearance at the 

maximum conductor temperature for which the line is designed to operate. E.ON states 

that what the Commission described as a “technological impediment” may be a desired 

design feature intended to address unique equipment protection issues or public safety 

concerns. 

141. Exelon asserts that phasing out step distance relays with mho circle operating 

characteristics could leave the electric system without any reliable backup for 

transmission lines with failed communication or other equipment failures, thereby 

exposing the system to faults that cannot be cleared and potentially resulting in larger 

outages and/or equipment damage. TAPS adds that the Commission’s proposal would 

result in the loss of zone 3/zone 2 relays as back-up protection in the event of a stuck 

breaker and/or a failure of a transfer trip scheme for a stuck breaker. 

142. The PSEG Companies speculate that the post-blackout relay mitigation programs 

conducted by NERC may have already mitigated the unexpected tripping of the 

transmission lines during the August 2003 blackout. The PSEG Companies add that it is 
Docket No. RM08-13-000 - 90 - 

 

possible that the only reason the blackout stopped was because these lines unexpectedly 

tripped. The PSEG Companies assert that the approach to stable power swings should be 

all encompassing and include the development and implementation of “islanding” 

strategies in conjunction with out-of-step blocking (or tripping) requirements. 

143. Several commenters dispute the virtues of the protection schemes discussed by the 

Commission in the NOPR. Ameren states that, in its experience, many of the 

applications identified by the Commission in the NOPR are less reliable than the step 

distance and directional comparison methods used in distance relays. Duke casts doubt 

on manufacturers’ claims that newer relay technology is able to differentiate between 

stable power swings and out-of-step conditions, pointing out that much of the newer 

technology is essentially the same as traditional out-of-step relay blocking schemes with 

variable timers. Duke also observes that some new protection systems still require relays 

to be set to operate on high load conditions and block tripping for a fault during a stable 

power swing. EEI states that the protection schemes cited by the Commission are prone 

to mis-operation due to loss of communication or timing differences in a transmit-andreceive communication path. EEI explains that on September 18, 2007, the protection 

schemes identified by the Commission actually created a major disturbance in the MRO 

region due to problems with communication circuits.125

125 EEI at 21-22. 
Docket No. RM08-13-000 - 91 - 

144. EEI argues that subject matter experts in the electric industry have found that the 

protection schemes cited by the Commission in the NOPR are significantly more difficult 

to install and maintain than step distance and directional comparison schemes using 

distance relays. EEI states, for example, that while line differential relays have been 

reliable when applied over fiber communications systems, the necessary schemes are 

expensive to install. Ameren adds that line differential relays are not as reliable as phase 

distance relays, which would still need to be installed to backup the communications 

system. Ameren also states that installation of fiber optics on existing transmission lines 

would require lengthy construction delays, and therefore create a reliability risk and delay 

compliance with PRC-023-1. 

145. EEI and Ameren also point out the limitations of out-of-step tripping and power 

swing blocking. They explain that in a 2005 report, the IEEE Power System Relaying 

Committee found that out-of-step tripping and power swing blocking cannot be set 

reliably under extreme multi-contingency conditions where the trajectories of power 

swings are unpredictable, because they must be set based on specific system 

contingencies and the results of stability simulations. 

146. Exelon argues that the technology identified by the Commission may not be 

helpful in a situation like the August 2003 blackout. Exelon explains that experienced 

relay protection engineers can apply the technology to distinguish between stable and 

unstable power swings in the cases of Category A, B, C and even some Category D 
Docket No. RM08-13-000 - 92 - 

contingencies as detailed in the TPL Reliability Standards, but that these are discrete 

contingencies that can be simulated with a great deal of certainty. Exelon states that 

simulating the types of swings that occurred during the August 2003 blackout would 

involve many scenarios, occurring in different possible sequences. Exelon claims that it 

is virtually impossible to accurately predict the exact sequence of events for major 

disturbances involving extreme events, and that without accurate simulations of the 

“right” disturbances, replacing relays would not provide any benefit. 

147. WECC and Tri-State make the related point that there were at least fourteen line 

outages before the stable swings began in the August 2003 blackout, and that it is 

unlikely that the multiple contingency scenarios that developed would ever have been 

studied under the current TPL Reliability Standards. WECC adds that even if the TPL 

Reliability Standards required prior study and relay coordination for such extensive 

outages, it is entirely plausible that the power swing blocking settings appropriate for a 

system that included 2 or 3 contingencies would not work appropriately for the same 

system after 14 or 40 outages. 

148. Multiple commenters claim that the Commission’s proposal would place an undue 

and unnecessary financial hardship on utilities because it would require significant 

expenditures and an exceptional amount of skilled labor without commensurate benefits. 

Exelon argues that any type of a proposed phase-out would affect a majority of the relays 

in North America. With respect to its PECO and ComEd operating companies, Exelon 
Docket No. RM08-13-000 - 93 - 

estimates that it would cost PECO approximately $45 million to comply for roughly 180 

terminals between 230 kV and 500 kV ($250,000 per terminal) and 33 percent more if the 

phase-out applied to 138 kV lines. As for ComEd, Exelon estimates that it would cost 

approximately $65 million to comply for roughly 260 terminals between 345 kV and 

765 kV, and three times more if the phase-out applied 138 kV lines. Portland General 

states that it would cost $6 million to replace its 40 relays. TAPS points out that Order 

No. 672 states that NERC may consider the cost of compliance when developing a 

Reliability Standard, provided that the Standard does not reflect the “lowest common 

denominator.” TAPS argues that PRC-023-1 does not reflect the “lowest common 

denominator.” 

149. EEI argues that the Commission’s proposal will require the unreasonable removal 

of a large number of electromechanical relays that effectively function, and that electric 

utilities should replace electromechanical relays only when necessary. Oncor argues that 

is unnecessary to mandate a phase out because as utilities upgrade their protection 

systems on a voluntary basis they will eliminate relays that cannot differentiate between 

faults and stable power swings. TAPS states that the Commission’s proposal, in 

combination with its proposal to eliminate the exclusions in Attachment A of PRC-023-1 

(particularly subsection (3.1)), would require redundant high speed protective systems for 

every transmission line, even when they are not needed for critical clearing time 

purposes. TAPS also argues that requiring the addition of new protective relay systems 
Docket No. RM08-13-000 - 94 - 

runs up against the prohibitions in sections 215 (a)(3) and (i)(2) of the FPA on Reliability 

Standards that require the enlargement of facilities or the addition of generation or 

transmission capacity. 

b. Commission Determination

150. We will not direct the ERO to modify PRC-023-1 to address stable power swings. 

However, because both NERC and the Task Force have identified undesirable relay 

operation due to stable power swings as a reliability issue, we direct the ERO to develop 

a Reliability Standard that requires the use of protective relay systems that can 

differentiate between faults and stable power swings and, when necessary, phases out 

protective relay systems that cannot meet this requirement. We also direct the ERO to 

file a report no later than 120 days of this Final Rule addressing the issue of protective 

relay operation due to power swings. The report should include an action plan and 

timeline that explains how and when the ERO intends to address this issue through its 

Reliability Standards development process. 

151. According to the NERC System Protection and Control Task Force, it is a well 

established principle of protection that Bulk-Power System elements, such as generators, 

transmission lines, transformers, and DC transmission or shunt devices, should not trip 

inadvertently for expected and potential non-fault loading conditions, including normal 
Docket No. RM08-13-000 - 95 - 

 

and emergency loading conditions and stable power swings.126 Before Congress’ 

directive in section 215 of the FPA to establish mandatory and enforceable Reliability 

Standards, this reliability principle was considered good utility practice and was 

documented in the voluntary NERC Planning Standards as one of the System and 

Protection and Control Transmission Protection Systems Guides.127 However, the ERO 

has not yet proposed to translate this principle into a mandatory and enforceable directive 

by including it in a Reliability Standard. 

152. Additionally, as we explained in the NOPR, while zone 3/zone 2 relays operated 

during the August 2003 blackout according to their settings and specifications, the 

inability of these relays to distinguish between a dynamic, but stable power swing and an 

actual fault contributed to the cascade.128 The Task Force also identified dynamic power 

swings and the resulting system instability as the reason why the cascade spread.129 

Since PRC-023-1 does not address relays operating unnecessarily because of stable 

126 NERC Planning Committee, System Protection and Control Task Force, “Relay 

Loadability Exceptions – Determination and Application of Practical Relaying 

Loadability Ratings,” Version 1.2, at 3 (Aug. 8, 2005). 

127 See NERC Planning Standards, Section III: System and Protection and 

Control, Part A: Transmission Protection Systems, G.12 (1997) (“Generation and 

transmission protection systems should avoid tripping for stable power swings on the 

interconnected transmission systems.”). Under the voluntary planning standards and 

operating policies, a “Guide” described good planning practices and considerations. 

128 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 58. 

129 See Final Blackout Report at 81-82. 
Docket No. RM08-13-000 - 96 - 

 

power swings, we are concerned that relays set according to PRC-023-1 remain 

susceptible to problems like those that occurred during the August 2003 blackout. 

153. While we recognize that addressing stable power swings is a complex issue, we 

note that more than six years have passed since the August 2003 blackout and there is 

still no Reliability Standard that addresses relays tripping due to stable power swings. 

Additionally, NERC has long identified undesirable relay operation due to stable power 

swings as a reliability issue. Consequently, pursuant to section 215(d)(5) of the FPA, we 

find that undesirable relay operation due to stable power swings is a specific matter that 

the ERO must address to carry out the goals of section 215, and we direct the ERO to 

develop a Reliability Standard addressing undesirable relay operation due to stable power 

swings. 

154. We note that NERC stated in its petition that PRC-023-1 interacts with several 

existing FAC, IRO, and TOP Reliability Standards, and that these interactions require 

limits to be established for all system elements, interconnected systems to be operated 

within these limits, operators to take immediate action to mitigate operation outside of 

these limits, and protective relays to refrain from operating until the observed condition 

on their protected element exceeds these limits.130 We agree, and add that entities must 

also validate protection settings set pursuant to PRC-023-1 through: (1) using the 

130 NERC Petition at 15-16. 
Docket No. RM08-13-000 - 97 - 

settings as an input into the valid assessments required for compliance with the TPL 

Reliability Standards for contingencies; (2) including the settings in the derivation of 

SOLs and IROLs; and (3) complying with the TOP, IRO, and FAC Reliability Standards 

for Category B contingencies, and for the subset of multiple contingencies (if any) 

identified in TPL-003 that result in stability limits identified by the planning authority. 

These steps will ensure Reliable Operation until the ERO develops the new Reliability 

Standard addressing unnecessary relay operation due to stable power swings. 

155. Although we do not direct the ERO to modify PRC-023-1 to address stable power 

swings, we disagree with those commenters who suggest that relay performance during 

stable power swings is outside the scope of relay loadability. Reliability Standard PRC023-1 was developed by industry experts using well thought-out guidelines based on 

static system conditions. These guidelines apply only to the situation in which the 

electric system after a disturbance has returned to a steady state condition. This means 

that currents and voltages on Bulk-Power System elements vary with a large degree of 

predictability. Under this scenario, compliance with PRC-023-1 will prevent relays from 

inadvertently tripping because of increases in static loadings; hence, the term 

“loadability.” 

156. However, protective relays will respond to real-time system conditions, regardless 

of whether they are set for static loadings (loadability) or dynamic loadings, such as 

stable power swings. During transient conditions, a protective relay set assuming steady-
Docket No. RM08-13-000 - 98 - 

 

state system conditions will measure the prevailing voltage and current quantities 

resulting from a stable power swing, and if its trajectory falls within the relay settings 

(reach and time delay) so derived from PRC-023-1, it will operate and inadvertently trip 

the healthy Bulk-Power System element it is protecting. Consequently, the relay may 

operate for transient conditions, even if set pursuant to PRC-023-1. Thus, relay operation 

because of stable power swings is within the scope of relay loadability and must be 

considered when the relay is set to ensure Reliable Operation. 

157. Exelon states that its stability studies for ComEd and PECO have never identified 

lines that would trip on stable power swings. There are two potential reasons why not: 

(1) Exelon’s protection systems are designed so that it is unnecessary to establish longer 

reach settings for protective relays; or (2) its electric systems consist primarily of short 

transmission lines. 

158. Initially, we note that ComEd and PECO may have historically adopted a good 

utility practice in protection that requires two groups (both of equivalent high speed) of 

redundant and duplicated communications-based protection systems for each high 

voltage line while relying on the use of local breaker failure protection.131 If this were 

131 See NERC Planning Standards, Section III: System and Protection and 

Control, Part A: Transmission Protection Systems, G.5 (1997) (“Physical and electrical 

separation should be maintained between redundant protection systems, where practical, 

to reduce the possibility of both systems being disabled by a single event or condition.”). 

While this is considered a good utility practice and used worldwide, it may not have 

(continued...) 
Docket No. RM08-13-000 - 99 - 

de 

 

the case, they would not need to set their relays to overreach by large margins to provi

remote circuit breaker failure and backup protection because they designed around the 

problem. In addition, the high voltage lines in ComEd and PECO may be relatively 

short. Electric systems comprised of long transmission lines are more likely to 

experience larger stable power swings than those comprised of short transmission lines. 

These two factors—relative short protection reach in their Zone 1 and Zone 2 relays due 

to application of more sophisticated protection systems and not relying on the use of 

remote breaker failure protection, as well as, smaller stable power swings due to shorter 

transmission lines—are likely to be the key reasons why they have never identified lines 

that would trip on stable power swings. 

159. We find unpersuasive Consumers Energy’s claim that heavy reactive power 

consumption, not stable power swings, contributed to the cascade during the August 2003 

blackout. In the Final Blackout Report, the Task Force addressed this issue and 

concluded that, as the cascade progressed beyond Ohio, it spread due not to insufficient 

reactive power and a voltage collapse, but because of dynamic power swings and the 

resulting system instability.132 While extreme reactive power consumption may have 

resulted in the operation of some communications-based relays, the Final Blackout 

necessarily been used by other entities in the past and is currently not required by any 

Reliability Standard. 

132 Final Blackout Report at 81. 
Docket No. RM08-13-000 - 100 - 

Report confirms that zone 3/zone 2 relays without communications or an uncoordinated 

time delay operated unnecessarily when they recognized dynamic, but stable, power 

swings as a fault. As the Task Force explained, this undesirable operation contributed to 

the cascade and the spread of the blackout. 

160. WECC argues that PRC-023-1 provides indirect protection against stable power 

swings because it prevents relays from tripping due to high loading, and that this 

protection could have prevented the tripping of the zone 3/zone 2 relays during the 

blackout and prevented the oscillations that caused “healthy” transmission lines to 

unnecessarily trip. While we agree that increasing loadability by applying the settings set 

forth in PRC-023-1 decreases the likelihood of relays tripping on load, it does not 

necessarily decrease the likelihood of zone 3/zone 2 relays applied as remote circuit 

breaker failure and backup protection tripping on stable power swings and would not 

have prevented the trips that spread the August 2003 blackout. Zone 3/zone 2 relays 

applied as remote circuit breaker failure and backup protection require large protective 

reach settings. The protective reach setting is determined by the apparent impedance of 

the system as measured by the relay. When the apparent impedance as measured by the 

relay falls within the setting of the relay, the relay will operate after its set time delay. 

While a fault typically moves through the characteristic of a relay reach setting very fast, 

the speed at which a power swing moves through the characteristic of a relay reach 

setting is typically much slower. When a power swing occurs, it is the time that it takes 
Docket No. RM08-13-000 - 101 - 

 

the power swing to pass through the characteristic of the relay’s protective reach setting 

that makes the relay susceptible to operation. As we explained in the NOPR, the Final 

Blackout Report found that several zone 2 relays applied as remote circuit breaker failure 

and backup protection were set to overreach their protected lines by more than 200 

percent without any time delay.133 When the dynamic, yet stable, power swings occurred 

prior to system cascade, these relays operated unnecessarily.134 

161. The PSEG Companies suggest that NERC’s post-blackout relay mitigation 

programs may have addressed the unexpected tripping of lines that occurred during the 

August 2003 blackout, and that it is possible that the only reason the blackout stopped 

was because these lines unexpectedly tripped. We disagree, based on two facts 

documented in the Final Blackout Report. First, the unexpected tripping of these lines in 

Ohio and Michigan accelerated the geographic spread of the cascade instead of stopping 

it.135 Second, relays on long lines that are not highly integrated into the electrical 

network, such as the Homer City-Watercure and the Homer City-Stolle Road 345-kV 

lines in Pennsylvania, tripped quickly and split the grid between the sections that blacked 

out and those that recovered without further propagating the cascade. We also disagree 

with the PSEG Companies’ assertion that NERC’s post-blackout relay mitigation 

133 Id. at 80. 

134 Id. at 82. 

135 Id. at 80. 
Docket No. RM08-13-000 - 102 - 

 

programs may have addressed the unexpected tripping of lines that occurred during the 

August 2003 blackout for two main reasons: (i) the programs did not include on a 

general basis sub-200 kV facilities that are considered as critical or operationally 

significant facilities;136 and (ii) the programs did not explicitly address inadvertent 

tripping on non-faulted facilities due to stable power swings. 

162. The PSEG Companies also assert that the Commission’s approach to stable power 

swings should be inclusive and include “islanding” strategies in conjunction with out-ofstep blocking or tripping requirements. We agree with the PSEG Companies and direct 

the ERO to consider “islanding” strategies that achieve the fundamental performance for 

all islands in developing the new Reliability Standard addressing stable power swings. 

163. We also clarify that our directive does not in any way involve a tradeoff between 

reliability and public safety as suggested by E.ON’s concerns about the maintenance of 

minimum vertical safety clearances and TAPS’s concerns about modifying relaying 

schemes to accommodate non-fault-related transient overloads. First, while the 

maintenance of minimum vertical safety clearances for personnel safety consideration is 

outside of Commission jurisdiction, the development of line ratings consistent with 

FAC-008-1 (Facility Ratings Methodology) must include the limiting factors, such as line 

design, ambient conditions and system loading conditions. For these ratings to be valid 

136 The Beyond Zone 3 review included sub-200 kV facilities on a limited basis. 
Docket No. RM08-13-000 - 103 - 

 

there must be adequate clearances between line conductors and surrounding objects to 

prevent flashover in addition to maintaining adequate vertical clearance from the ground. 

Reliability Standard FAC-003-1 Requirement R1.2.1 also includes a provision for 

“worker approach distance requirements” as part of the minimum clearances which 

include vertical safety clearance. Therefore, we do not see how our directive would in 

any way involve a tradeoff between reliability and safety as these are addressed 

separately and interactively between the relevant Reliability Standards. 

164. Second, we do not see how the Commission’s goal of avoiding inadvertent 

tripping of non-faulted Bulk-Power System elements due to stable power swings can be 

interpreted as requiring modifying relaying schemes to accommodate non-fault related 

transient overloads, as TAPS claims. In addition to our explanation above, NERC stated 

in its petition, and we agree, that PRC-023-1 interacts with existing FAC, IRO, and TOP 

Reliability Standards; these interactions require limits to be established for all system 

elements, interconnected systems to be operated within these limits, operators to take 

immediate action to mitigate operation outside of these limits (i.e., overloads), and 

protective relays to refrain from operating until the observed condition on their protected 

element exceeds these limits.137 In addition, each planning authority and transmission 

planner is required to demonstrate through a valid assessment only that its portion of the 

137 NERC Petition at 15-16. 
Docket No. RM08-13-000 - 104 - 

interconnected electric system is evaluated for the risks and consequences of such 

extreme, multi-contingency events and for corrective actions. For these reasons, we also 

reject TAPS’s comments that the NOPR proposal would create safety issues due to 

overloading from multiple or extreme contingencies. If protection systems already 

respect safety issues, they will not be affected by following the evaluation of these 

extreme contingencies. 

165. We also disagree with commenters’ claims that our directive could harm 

reliability. Exelon asserts that phasing out step distance relays with mho circle operating 

characteristics could leave the electric system without any reliable backup for 

transmission lines with failed communication or other equipment failures, thereby 

exposing the system to faults that cannot be cleared and potentially resulting in larger 

outages and/or equipment damage. TAPS adds that the Commission’s proposal would 

result in the loss of zone 3/zone 2 relays as back-up protection in the event of a stuck 

breaker and/or a failure of a transfer trip scheme for a stuck breaker. 

166. Exelon incorrectly interprets our statement that “a protective relay system that 

cannot refrain from operating under non-fault conditions because of a technological 

impediment is unable to achieve the performance required for reliable operation” as a 

proposal for “leaving the electric system without any reliable backup for transmission.” 

TAPS’ similar assertion implies the same. We disagree that the Commission’s proposal 

would result in the loss of relays as back-up protection. Our statement merely points out 
Docket No. RM08-13-000 - 105 - 

the fundamentals required for Reliable Operation under currently approved Reliability 

Standards. As we state in the previous discussion, PRC-023-1 interacts with existing 

FAC, IRO, and TOP Reliability Standards to ensure Reliable Operation; these 

interactions require limits to be established for all system elements, interconnected 

systems to be operated within these limits, operators to take immediate action to mitigate 

operation outside of these limits, and protective relays to refrain from operating until the 

observed condition on their protected element exceeds these limits. Protection relays 

include primary and backup relays. If zone 2/zone 3 relays are used by entities as part of 

their protection systems designed to achieve the system performance, they can remain as 

backup protection as long as they do not inadvertently trip non-faulted facilities due to 

stable power swings. 

167. Several commenters dispute the virtues of the protection schemes discussed by the 

Commission in the NOPR. In general, these commenters argue that the applications 

identified by the Commission in the NOPR are less reliable than the step distance and 

directional comparison methods used in distance relays. We clarify that the protection 

systems discussed in the NOPR are merely examples of systems that can differentiate 

between faults and stable power swings. We leave it to the ERO to determine the 

appropriate protection systems to be discussed in the new Reliability Standard through 

application of its technical expertise. 
Docket No. RM08-13-000 - 106 - 

168. Some commenters argue that the technology identified by the Commission may 

not be helpful in a situation like the August 2003 blackout because that event involved so 

many contingencies that it would be almost impossible to simulate and thus unlikely to be 

studied under the TPL Reliability Standards. We realize that relays cannot be set reliably 

under extreme multi-contingency conditions covered by the Category D contingencies of 

the TPL Reliability Standards. In fact, Reliability Standard TPL-004-0 requires the 

planning authority and transmission planner to demonstrate through a valid assessment 

that its portion of the interconnected electric system is evaluated only for the risks and 

consequences of such events; it does not require corrective actions. We recognize that, 

because of the operating characteristic of the impedance relay, regardless of whether a 

power swing is stable or unstable, the relay may potentially operate under Category D 

contingencies. Thus, the NOPR proposed alternative protection applications and relays 

that are less susceptible to transient or dynamic power swings. This is consistent with 

Order No. 693, where the Commission stated that it is not realistic to expect the ERO to 

develop Reliability Standards that anticipate every conceivable critical operating 

condition applicable to unknown future configurations for regions with various 

configurations and operating characteristics.138

 138 See Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1706. 
Docket No. RM08-13-000 - 107 - 

 

169. Some commenters oppose a new Reliability Standard because they are concerned 

that it would require the removal of a large number of electro-mechanical relays that are 

in service and functioning today. Likewise, other commenters argue that the cost of 

phasing out protection systems that cannot distinguish between faults and stable power 

swings is excessive. While we appreciate these concerns, they are not persuasive reasons 

to reconsider our decision to direct the ERO to develop a Reliability Standard addressing 

undesirable relay operation due to stable power swings. In this Final Rule, we have 

explained why a relay’s inability to distinguish between actual faults and stable power 

swings is a specific matter that the ERO must address in order to carry out the goals of 

section 215 of the FPA, in part by showing how such relays contributed to the spread of 

the August 2003 blackout. The fact that many such relays are in current use does not 

mitigate the threat they pose to Reliable Operation or change the role they played in 

spreading the August 2003 blackout. Moreover, while we direct the ERO to develop a 

Reliability Standard that phases out such relays where necessary if they do not meet the 

reliability goal, the ERO is free to develop an alternative solution to our reliability 

concerns regarding undesirable relay operation due to stable power swings, provided that 

it is an equally effective and efficient approach.139 

139 Id. P 186. 
Docket No. RM08-13-000 - 108 - 

 

170. Because we direct the ERO to develop the new Reliability Standard in this Final 

Rule, it would be premature for the Commission to now rule on issues related to the cost 

of the new Standard. In the first place, the Reliability Standard is not yet written; the 

ERO has not yet worked out the details of a phase-out, or even decided if it will propose 

a phase-out or some other equally effective and efficient solution to the Commission’s 

reliability concerns. It is impossible for the Commission to evaluate the costs of a 

proposal that has not yet been developed, let alone one that has not has yet been 

presented to the Commission. Entities will have the opportunity to raise their cost 

concerns throughout the Reliability Standards development process and before the 

Commission when NERC submits the new Reliability Standard for Commission 

approval. As a general matter, however, we repeat our statement in Order No. 672: 

proposed Reliability Standards must not simply reflect a compromise in the ERO’s 

Reliability Standard development process based on the least effective North American 

practice – the so-called “lowest-common denominator” – if such practice does not 

adequately protect Bulk-Power System reliability.140 While a Reliability Standard may 

take into account the size of the entity that must comply and the costs of implementation, 

the ERO should not propose a “lowest common denominator” Reliability Standard that 

would achieve less than excellence in operating system reliability solely to protect against 

140 Order No. 672, FERC Stats. & Regs. ¶ 31,204 at P 329. 
Docket No. RM08-13-000 - 109 - 

 

reasonable expenses for supporting vital national infrastructure.141 The Commission has 

also explained that the Reliability Standard development process should consider, at a 

high level, the potential costs and other risks to society of a Bulk-Power System failure if 

action is not taken to establish and implement a new or modified Reliability Standard in 

response to previous blackouts and the economic impacts associated with such 

blackouts.142

171. We also disagree with TAPS’s claim that the Commission’s proposal, in 

combination with its proposal to eliminate the exclusions in Attachment A of PRC-023-1 

(particularly subsection 3.1), would require redundant high speed protective systems for 

every transmission line, even when they are not needed for critical clearing time 

purposes. As we have explained previously in this Final Rule, the TPL Reliability 

Standards require annual system assessments to determine if the system meets the desired 

system performance requirement established by the TPL Standards. This assessment 

includes the interaction of approved Reliability Standards such as, PRC, IRO, and TOP. 

If an entity is not able to achieve the desired system performance, consistent with the 

TPL Reliability Standards, corrective action plans must be developed and implemented. 

Thus, it is left to the entity to determine how best to meet desired system performance 

141 Id. P 330. 

142 ERO Rehearing Order, 117 FERC ¶ 61,126 at P 97. 
Docket No. RM08-13-000 - 110 - 

when it develops its corrective action plans; contrary to TAPS’s argument, our directives 

in this Final Rule do not require entities to adopt redundant high speed protective systems 

for every transmission line as a specific corrective action plan. 

172. Finally, we reject TAPS’s assertion that requiring entities to use protection 

systems that can distinguish between faults and stable power swings violates 

sections 215(a)(3) and (i)(2) of the FPA, which prohibit the Commission from requiring 

in a Reliability Standard the enlargement of facilities or the addition of generation or 

transmission capacity. Replacing a protection system that does not ensure Reliable 

Operation in this instance is necessary to achieve the goals of the statute and does not 

equate to an expansion of facilities or the construction of new generation or transmission 

capacity. 

173. In sum, we adopt the NOPR proposal and direct the ERO to develop a new 

Reliability Standard that prevents protective relays from operating unnecessarily due to 

stable power swings by requiring the use of protective relay systems that can differentiate 

between faults and stable power swings and, when necessary, phases-out relays that 

cannot meet this requirement. NERC requests that the Commission allow PRC-023-1 to 

remain focused on steady state relay loadability and leave stable power swings to be 

specifically addressed in a different Reliability Standard. We agree that this is a 

reasonable approach. Meanwhile, to maintain reliability, the Commission expects 
Docket No. RM08-13-000 - 111 - 

entities to continue to include the effects of protection settings in TPL and TOP 

assessments for future systems and in the determination of IROLs and SOLs.143 

F. Requirement R1

174. Requirement R1 directs each subject entity to set its relays according to one of the 

criteria prescribed in sub-requirements R1.1 through R1.13. In the NOPR, the 

Commission expressed concerns about the implementation of three of these criteria: 

sub-requirements R1.2, R1.10, and R1.12. In its comments, Palo Alto raised concerns 

about sub-requirement R1.1. 

1. Sub-Requirement R1.1

175. Sub-requirement R1.1 specifies transmission line relay settings based on the 

highest seasonal facility rating using the 4-hour thermal rating of a transmission line, plus 

a design margin of 150 percent. 

a. Comments

176. Palo Alto states that, in the interest of maximum reliability, many municipal 

utilities install lines and transformers rated to handle the worst-case emergency load, i.e., 

 143 Requirement R1.3.10 of Reliability Standard TPL-002-0 requires that a valid 

assessment shall include, among other things, the effects of existing and planned 

protection systems. Requirement R6 of Reliability Standard TOP-002-0 requires that, as 

a minimum criterion, the bulk electric system is planned and operated to maintain reliable 

operation for the single contingency loss of any transmission facility. In Order No. 693, 

the Commission explained that “[i]n deriving SOLs and IROLs, moreover, the functions, 

settings, and limitations of protection systems are recognized and integrated.” Order 

No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1435. 
Docket No. RM08-13-000 - 112 - 

the load resulting from the failure of an adjacent line or transformer. Palo Alto explains 

that load-sensitive overcurrent relays are typically set between 115 and 125 percent of the 

highest line or equipment rating, and argues that changing these settings to comply with 

sub-requirement R1.1 will result in longer fault clearing times and unnecessarily 

compromise line and transformer protection. Palo Alto adds that longer fault clearing 

times could result in increased arc flash exposure. Palo Alto recommends that the 

Commission direct NERC to revise sub-requirement R1.1 to state that transmission relays 

can be set to not operate at or below 150 percent of the transmission line/transformer 

rating instead of the highest seasonal facility rating of a circuit, or at 120 percent of the 

maximum expected emergency load on the transmission line or transformer. 

b. Commission Determination

177. Palo Alto identifies a technical disagreement with sub-requirement R1.1. We 

expect such technical disagreements to be resolved either in the Reliability Standards 

development process or by the disagreeing entity requesting an exception from NERC. 

Moreover, giving “due weight” to the technical expertise of the ERO, we find no reason 

to direct a change to sub-requirement R1.1. 

2. Sub-Requirement R1.2

178. Sub-requirement R1.2 requires relays to be set not to operate at or below 115 

percent of the highest seasonal 15-minute facility rating of a circuit. A footnote attached 

to sub-requirement R1.2 provides that “[w]hen a 15-minute rating has been calculated 
Docket No. RM08-13-000 - 113 - 

and published for use in real-time operations, the 15-minute rating can be used to 

establish the loadability requirement for the protective relays.” 

a. NOPR Proposal

179. In the NOPR, the Commission expressed concern that sub-requirement R1.2 might 

conflict with Requirement R4 of existing Reliability Standard TOP-004-1 (Transmission 

Operations), which states that “if a transmission operator enters an unknown operating 

state, it will be considered to be in an emergency and shall restore operations to respect 

proven reliability power system limits within 30 minutes.”144 The Commission explained 

that the transmission operator (or any other reliability entity affected by the facility) 

might conclude that it has 30 minutes to restore the system to normal when in fact it has 

only 15 minutes because the relay settings for certain transmission facilities have been set 

to operate at the 15-minute rating in accordance with sub-requirement R1.2. In order to 

avoid confusion and protect reliability, the Commission proposed to direct the ERO to 

revise sub-requirement R1.2 to give transmission operators the same amount of time as in 

Reliability Standard TOP-004-1; develop a new requirement that transmission owners, 

generation owners, and distribution providers give their transmission operators a list of 

transmission facilities that implement sub-requirement R1.2; or propose an equally 

effective and efficient way to avoid the potential conflict. 

 144 See Reliability Standard TOP-004-1, Requirement R4. 
Docket No. RM08-13-000 - 114 - 

b. Comments

180. NERC urges the Commission to adopt sub-requirement R1.2 without directing a 

change. NERC states that the purpose of the footnote is to inform the user that, if it 

decides to implement sub-requirement R1.2, it must have a procedure that operators 

implement and follow. NERC states that some system operators use a 15-minute rating 

during system contingencies, which is a more stringent requirement than that established 

in TOP-004-1. NERC also claims that use of the 15-minute rating to establish loadability 

reflects a commitment on the part of the entity to operate to the 15-minute rating and to 

respond to rating violations within the 15 minutes because the entity can use the 15-

minute rating only if it has calculated and published it for use in real-time operations.145 

181. Oncor states that the Commission’s concerns seem reasonable and that a simple 

solution to the conflict would be to provide system operators with a copy of those lines 

that have a 15-minute rating along with the 30-minute rating of transmission lines as 

described in TOP-004-1.146 IESO and Hydro One argue that if the Commission acts on 

its proposal, creating a new requirement is the preferred approach in order to avoid 

having a requirement specified in one Reliability Standard actually applying to another 

Standard.

 145 NERC Comments at 28. 

146 Oncor at 5. 
Docket No. RM08-13-000 - 115 - 

182. Some commenters maintain that entities that use the 15-minute rating are fully 

capable of operating within this constraint. Duke explains that transmission operators are 

trained to operate the system within the ratings established and communicated to them 

pursuant to FAC-009-1, and adds that reliability coordinators, planning authorities, 

transmission planners, and transmission operators already receive these ratings pursuant 

to Requirements R1 and R2 of FAC-009-1. Southern states that general industry 

practice, which is reflected in Reliability Standard TOP-004-1, is to return the electric 

system to a normal and reliable state in less than 30 minutes. 

183. Several commenters challenge the Commission’s claim that there is a conflict 

between PRC-023-1 and TOP-004-1 and that transmission operators might conclude that 

they have 30 minutes to restore the system to normal when in fact they have only 15 

minutes because the relay settings for certain transmission facilities have been set to 

operate at the highest seasonal 15-minute rating in accordance with sub-requirement 

R1.2. As an initial matter, Dominion points out that the Commission’s statement 

mischaracterizes sub-requirement R1.2; rather than allow for relays to operate at the 15- 

minute rating, sub-requirement R1.2 specifies that relays must be set so that they do not

operate at or below 115 percent of the 15 minute rating. APPA, Ameren, BPA, 

Dominion, EEI, and WECC further explain that sub-requirement R1.2 does not establish 

a time limit before relays trip; instead, it specifies the level of loading used to develop the 

relay’s setting. In other words, according to these commenters, the 15-minute rating does 
Docket No. RM08-13-000 - 116 - 

not mean that the relays will trip after 15 minutes. APPA clarifies that 15 minutes is the 

time that the facility ratings methodology has determined the line can safely be loaded at 

that level. BPA, Dominion, EEI, and WECC explain that relays set according to subrequirement R1.2 will not trip until loading exceeds 115 percent of the 15 minute rating, 

which will always be higher than the 30-minute rating. EEI and Ameren acknowledge 

that using 115 percent of the highest seasonal 15-minute rating creates more conservative 

relay load limits, but point out that this does not limit the operator’s response time to 15 

minutes.

184. TAPS and Dominion contend that the time periods identified in sub-requirement 

R1.2 and TOP-004-1 refer to two distinct operating situations. TAPS and Dominion state 

that the 15-minute rating referenced in sub-requirement R1.2 refers to the time to respond 

to a contingency in a known state (i.e., within the emergency rating), while the 30-minute 

period in TOP-004-1 refers to the time to respond to an unknown state (i.e., in a situation 

where the operating limits are unknown, typically a state that has not been studied in 

stability studies to identify stability limits). 

185. Duke, EEI, and the PSEG Companies challenge what they perceive to be the 

Commission’s assumption that sub-requirement R1.2 is for overload protection. They 

state that overcurrent relays are designed and applied for fault protection and not for 

overload protection. EEI adds that the Commission should recognize that subrequirement R1.11 is the requirement addressing overload protection. The PSEG 
Docket No. RM08-13-000 - 117 - 

Companies assert that it is widely recognized by industry that the purpose of PRC-023-1 

is to ensure that lines refrain from tripping for maximum loading conditions; once the 

maximum loading conditions are exceeded the relays are free to operate for a fault.

c. Commission Determination

186. We decline to adopt the NOPR proposal to require the ERO to revise subrequirement R1.2 to mirror Reliability Standard TOP-004-1. However, we will adopt the 

NOPR proposal to direct the ERO to modify PRC-023-1 to require that transmission 

owners, generator owners, and distribution providers give their transmission operators a 

list of transmission facilities that implement sub-requirement R1.2. We agree with Oncor 

that this is a simple approach to addressing the potential for confusion identified by the 

Commission in the NOPR. Consistent with Order No. 693, we do not prescribe this 

specific change as an exclusive solution to our concerns regarding sub-requirement R1.2. 

As the Commission stated in Order No. 693, where, as here, “the Final Rule identifies a 

concern and offers a specific approach to address the concern, we will consider an 

equivalent alternative approach provided that the ERO demonstrates that the alternative 

will address the Commission’s underlying concern or goal as efficiently and effectively 

as the Commission’s proposal.”147 As discussed in the NOPR, the Commission is 

concerned that the transmission operator (or any other reliability entity affected by the 

 147 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 186. 
Docket No. RM08-13-000 - 118 - 

facility) might conclude that it has 30 minutes to restore the system to normal when in 

fact they may have less than 30 minutes because the relay settings applied to protect 

certain transmission facilities may have been set to operate applying a 15-minute rating in 

accordance with sub-requirement R1.2. 

187. Contrary to some commenters’ assertions, the Commission has not misunderstood 

the purpose of the 15-minute rating and the relay set points in sub-requirement R1.2. We 

realize that the 15-minute and 4-hour ratings are the times that the entity’s rating 

methodology has determined that a facility can safely be loaded at that level and does not 

correlate to the operating time of the protective relay. We also realize that the protective 

relays on these facilities should not operate until loading on the facility exceeds the 

protective relay settings, including impedance or current settings and time delays. 

Moreover, we understand that sub-requirement R1.2 is not for overload protection, and 

we agree that entities that use the 15-minute rating are expected to be capable of 

operating within this constraint. Our goal with directing a modification to subrequirement R1.2 is simply to ensure that the transmission operator has full knowledge of 

which facilities are applying a 15-minute rating instead of a 4-hour rating so that the 

transmission operator can factor this information into any necessary emergency actions. 

188. We also agree with TAPS and Dominion that the 15 minutes referred to in subrequirement R1.2 is for operating to a known 15-minute limit and therefore serves a 

purpose different from the 30 minutes allowed in TOP-004-1 for operators in an 
Docket No. RM08-13-000 - 119 - 

 

unknown operating state that must return to a known operating state. However, once the 

relay settings of a facility that implements sub-requirement R1.2 go above 115 percent of 

the facility’s 15-minute rating, the facility may trip and add to the outages that the 

transmission operator must address. Simply put, the Commission is directing this 

modification so that the requirement includes what Duke and others said they expect 

would be necessary for the operator to have sufficient information to reliably operate the 

system—knowledge of which facilities implement PRC-023-1 criteria applying a 15-

minute rating so that the operator can utilize the system for the 15-minutes that the rating 

allows. Therefore, the Commission agrees that, while the time periods indentified in 

PRC-023-1 and TOP-004-1 are for different purposes, the operator’s response time for 

both and the consequences of inaction are effectively the same. 

189. Mandatory Reliability Standards should be clear and unambiguous regarding what 

is required and who is required to comply.148 This is not the case with sub-requirement 

R1.2. For example, the ERO states in its comments that entities that implement subrequirement R1.2 commit to operate to the 15-minute rating and to respond to rating 

violations within the 15 minutes.149 While we agree with the ERO, EEI and Ameren do 

not interpret sub-requirement R1.2 to limit the operator’s response time to 15-minutes. 

148 Order No. 672, FERC Stats. & Regs. ¶ 31,204 at P 325. 

149 NERC Comments at 28. 
Docket No. RM08-13-000 - 120 - 

Because there are different understandings with regard to the implementation of subrequirement R1.2, we adopt the NOPR proposal and direct the ERO to develop a new 

requirement that transmission owners, generator owners, and distribution providers give 

their transmission operators a list of transmission facilities that implement subrequirement R1.2. 

3. Sub-Requirement R1.10

190. Sub-requirement R1.10 provides criteria for transformer fault relays and 

transmission line relays on transmission lines that terminate in a transformer. It requires 

that relays be set so that the transformer fault relays and transmission line relays do not 

operate at or below the greater of 150 percent of the applicable maximum transformer 

name-plate rating (expressed in amperes), including the forced cooled ratings 

corresponding to all installed supplemental cooling equipment, or 115 percent of the 

highest owner-established emergency transformer rating. 

a. NOPR Proposal

191. In the NOPR, the Commission expressed concern that overloading facilities at any 

time, but especially during system faults, could lower reliability and present a safety 

concern. The Commission explained that the application of a transmission line 

terminated in a transformer enables the transmission owner to avoid installing a bus and 

local circuit breaker on both sides of the transformer. The Commission stated that, for 

this topology, protective relay settings implemented according to sub-requirement R1.10 
Docket No. RM08-13-000 - 121 - 

would allow the transformer to be subjected to overloads higher than its established 

ratings for unspecified periods of time. The Commission stated that this negatively 

impacts reliability and raises safety concerns because transformers that have been 

subjected to currents over their maximum rating have been recorded as failing violently, 

resulting in substantial fires. The Commission acknowledged that safety considerations 

are outside of its jurisdiction, but asserted that requirements in a Reliability Standard 

should not be interpreted as requiring unsafe actions or designs. The Commission 

proposed, therefore, to direct the ERO to submit a modification that requires any entity 

that implements sub-requirement R1.10 to either verify that the limiting piece of 

equipment is capable of sustaining the anticipated overload current for the longest 

clearing time associated with the fault from the facility owner or alter its protection 

system or topology. 

b. Comments

192. NERC states that the primary source of technical information for sub-requirement 

R1.10 is IEEE Standard C37.91-2008, IEEE Guide for Protecting Power Transformers 

(specifically, sections 8.6 and 8.6.1 and Appendix A).150 NERC explains that phase 

 

(continued...) 

150 NERC explains that sections 8.6 and 8.6.1 of the Guide address the settings of 

transformer phase overcurrent protection, and Appendix A contains through-fault 

duration curves for various size power transformers that provide fault current durations as 

plotted against transformer base current. Section 8.6 states: 
Docket No. RM08-13-000 - 122 - 

 

overcurrent devices must coordinate with duration curves, and that minimum current 

stated on the curves must equal two times transformer base current. NERC argues that 

PRC-023-1 is consistent with IEEE Standard C37.91-2008 and IEEE Standard C57.109-

8.6. Protection of a transformer against damage due to the failure to clear an 

external fault should always be carefully considered. This damage usually 

manifests itself as internal, thermal, or mechanical damage caused by fault 

current flowing through the transformer. The curves in Annex A show 

through-fault-current duration curves to limit damage to the transformer. 

Through-faults that can cause damage to the transformer include restricted 

faults or those some distance away from the station. The fault current, in 

terms of the transformer rating, tends to be low (approximately 0.5 to 5.0 

times transformer rating) and the bus voltage tends to remain at relatively 

high values. The fault current will be superimposed on load current, 

compounding the thermal load on the transformer. Several factors will 

influence the decision as to how much and what kind of backup is required 

for the transformer under consideration. Significant factors are the 

operating experience with regard to clearing remote faults, the cost 

effectiveness to provide this coverage considering the size and location of 

the transformer, and the general protection philosophies used by the utility. 

Section 8.6.1 states 

8.6.1. When overcurrent relays are used for transformer backup, their 

sensitivity is limited because they should be set above maximum load 

current. Separate ground relays may be applied with the phase relays to 

provide better sensitivity for some ground faults. Usual considerations for 

setting overcurrent relays are described in 8.3. When overcurrent relays are 

applied to the high-voltage side of transformers with three or more 

windings, they should have pickup values that will permit the transformer 

to carry its rated load plus margin for overload. . . .When two or more 

transformers are operated in parallel to share a common load, the 

overcurrent relay settings should consider the short-time overloads on one 

transformer upon loss of the other transformer. Relays on individual 

transformers may require pickup levels greater than twice the forced cooled 

rating of the transformer to avoid tripping. 
Docket No. RM08-13-000 - 123 - 

 

1993 (which is referenced in Appendix A of IEEE Standard C37.91-2008) because it 

requires entities that use overcurrent relays to consider loadability (a non-fault induced 

transformer loading), and because a setting of 150 percent of the transformer nameplate 

rating or 115 percent of the highest operator-established emergency rating will always be 

less than 200 percent of the transformer forced-cooled nameplate rating.151 

193. TAPS describes the Commission’s assertion that a “Reliability Standard should 

not be interpreted as requiring unsafe actions or designs” as a “jurisdictional bootstrap” 

that nevertheless fails to remove questions about the Commission’s authority to require a 

modification that addresses safety concerns. TAPS explains that section 215(i)(2) of the 

FPA provides that states retain jurisdiction over safety concerns, a point that the 

Commission acknowledged in the NOPR. 

194. Several commenters point out that protective relays are designed to protect the 

system from faults, not overloads.152 Ameren, EEI, and Duke observe that other 

protection methods, such as temperature monitors, are typically employed for thermal 

protection. WECC observes that sub-requirement R1.11 addresses overload protection. 

EEI adds that there is no loadability issue if a remote breaker can provide adequate 

protection and the asset owner can still comply with PRC-023-1. 

151 NERC Comments at 30. 

152 See, e.g., Ameren, BPA, Duke, EEI, Exelon, NERC, and WECC. 
Docket No. RM08-13-000 - 124 - 

195. Consumers Energy, EEI, and NERC argue that the mitigation of thermal overloads 

is best left to operator response, not to automatic devices, so that the operator may take 

well-reasoned action that best supports the Reliable Operation of the bulk electric system 

while addressing the overload. Consumers Energy argues that any entity that wishes to 

establish automatic actions for overload conditions should apply devices designed 

specifically for that purpose, with response times appropriate for overload, or should 

develop and install a special protection system in accordance PRC-012-0 to detect and 

take actions to relieve the overload. EEI maintains that any transformer requiring 

overload protection should have it specifically applied regardless of transmission line 

protection, or system configuration. Ameren and EEI contend that providing adequate 

transformer protection is in the best interest of the asset owner. The PSEG Companies 

argue that the Commission’s proposal is beyond the scope of PRC-023-1 because it is 

responsibility of the protection system designer to employ good engineering practice to 

ensure protection for faulted systems. Similarly, the PSEG Companies argue that system 

operations groups are responsible for ensuring that equipment is properly protected and 

loaded within limits. 

196. NERC states that overcurrent relays are typically used only for backup detection 

of through-faults outside of the primary protective zone. NERC maintains that a 

transformer subjected to a through-fault for an extended period of time may compromise 

its design, but that if an entity wishes to provide overload protection for its transformer, 
Docket No. RM08-13-000 - 125 - 

such protection should be provided by devices designed for that purpose and have 

response times appropriate for overload protection (e.g., several seconds and longer). 

BPA makes the similar claim that the overload current capability required by PRC-023-1 

for transformers is not a safety concern for moderate time durations. BPA explains that 

these setting levels (or higher) have been common in the industry to prevent relay 

operation on load. BPA acknowledges that, over prolonged periods, these overload 

currents could cause overheating which could reduce the life of the transformer. BPA 

states, however, that protective relays are not intended to protect for these currents 

because ample time is available for system operators to make system changes to mitigate 

the transformer overload in a controlled manner, which is preferable to automatic relay 

operation. BPA adds that there are other protective relays to protect the transformer from 

internal faults or large through-currents due to faults outside of the transformer. 

197. Several commenters argue that the Commission’s proposal is unnecessary. EEI 

argues that the Commission’s proposal is unnecessary because zone 2 time-delayed 

relays are typically set to operate in less than one second, while IEEE Standard C57.109-

1993 establishes the thermal damage curve for transformers above 30 MVA and allows 

25 times rated transformer current for two seconds. EEI also states that all transformers 

have an overload capability that has been covered by system dispatcher action regardless 

of its connection method. EEI points out that sub-requirement R1.10 requires load 

responsive transformer relays to be set to carry at least 150 percent of the transformer 
Docket No. RM08-13-000 - 126 - 

nameplate rating, and that system dispatcher response time is based on the degree of 

overload, not the connection method. EEI states that sub-requirement R1.10 allows 

conservative line protection, which improves the setting at which relays can be set to 

sense fault conditions. Duke adds that facility ratings, including transformer facility 

ratings, are established and communicated to reliability coordinators, planning 

authorities, transmission planners, and transmission operators in accordance with 

FAC-009-1, Requirements R1 and R2, and that each transmission operator is trained to 

operate the system within the ratings that are established and communicated to it pursuant 

to FAC-009-1. 

198. Exelon claims that the Commission’s description of sub-requirement R1.10 is 

inaccurate. Exelon maintains that sub-requirement R1.10 will not allow transformers to 

be subjected to overloads higher than their ratings for unspecified periods. Exelon claims 

that sub-requirement R1.10 addresses fault protection for lines terminated with a 

transformer – not transformer loading. Exelon states that the protection systems that 

protect against faults are different from the protection systems that protect against 

overloads. 

199. Exelon claims, moreover, that the Commission’s proposed modification is 

imprecise. Exelon explains that the term “the longest clearing time associated with the 

fault from the facility owner” leaves open the question of what assumptions should be 

used. For example, Exelon states that it is unclear whether the time period to be 
Docket No. RM08-13-000 - 127 - 

measured is based on normal backup clearing time or some other interval. Exelon 

contends that without such precision, compliance with any modified requirement will be 

impossible. 

200. Basin agrees that the Commission has a valid concern when it comes to 

establishing overload limits without regard to whether the limiting piece of equipment is 

capable of sustaining the overload for the longest clearing time associated with the fault. 

Basin argues, however, that the Commission’s mixture of terminologies in the NOPR 

(e.g., thermal ratings, fault current, load current and faults) is misleading in terms of 

cause and effect and risk management. Basin requests, therefore, that the Commission 

direct NERC to make the change using language that is clear and consistent. 

201. Basin argues, however, that the Commission should not impose any additional 

requirements on lines terminating in transformers. Basin explains that while this 

equipment is susceptible to damage from overloads, other equipment also is subject to 

overload-related damage and the Commission should not address this issue on a 

piecemeal basis. Basin contends that the safety issue related to lines terminating in 

transformers merits unique consideration and is outside the scope of this proceeding. 

Basin argues, therefore, that the Commission should not direct any specific actions with 

respect to such equipment in this docket. 

202. Tri-State agrees with the Commission that it is prudent to ensure that relays 

operate before the appropriate transformer damage curve is intersected. Tri-State adds 
Docket No. RM08-13-000 - 128 - 

that it finds little difference in the proposed allowable current sensing settings used in 

sub-requirements R1.10 and R1.11 except for the use of the term “fault protection” in 

sub-requirement R1.10 and “overload protection” in sub-requirement R1.11. 

c. Commission Determination

203. We adopt the NOPR proposal and direct the ERO to modify sub-requirement 

R1.10 so that it requires entities to verify that the limiting piece of equipment is capable 

of sustaining the anticipated overload for the longest clearing time associated with the 

fault.153 As with our other directives in this Final Rule, we do not prescribe this specific 

change as an exclusive solution to our reliability concerns regarding sub-requirement 

R1.10. As we have stated, the ERO can propose an alternative solution that it believes is 

an equally effective and efficient approach to addressing the Commission’s concern that 

entities respect facility limits when implementing sub-requirement R1.10. 

204. At the outset, we acknowledge that section 215 of the FPA does not authorize the 

Commission to set and enforce compliance with standards for the safety of electric 

facilities or services.154 While the NOPR identified a potential safety issue with subrequirement R1.10, we clarify that we do not rest our decision to adopt the NOPR 

proposal on safety concerns and reject TAPS’s contrary assertion. 

 153 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 186. 

154 16 U.S.C. 824o(i)(2). 
Docket No. RM08-13-000 - 129 - 

205. We also clarify that the Commission’s use of the term “overload” in the NOPR 

refers to the combination of load and fault current external to the transformer zone of 

protection (through-current) that can flow through the transformer. These overload 

currents can be higher than the transformer’s established ratings, subjecting the 

transformer to possible thermal damage. As discussed in the NOPR, and as NERC and 

Basin confirm, subjecting transformers to overloads over their maximum rating 

compromises their design and subjects the transformer to overload-related damage. 

Thus, we reject Exelon’s assertion that sub-requirement R1.10 will not allow 

transformers to be subjected to through-currents that would overload the transformer. 

206. Since sub-requirement R1.10 applies to the topology where there is no breaker 

installed on the high-voltage side of the transformer, faults within the transformer or at 

the low-voltage side of the transformer are cleared by tripping the remote breaker on the 

transmission line and the transformer low-voltage breaker. Because faults on the lowvoltage side of the transformer will generally be lower in magnitude as measured at the 

remote breaker due to the large impedance of the transformer, fault protection relays set 

at 150 percent of the transformer nameplate rating or 115 percent of the highest operator 

established emergency transformer rating may be set too high to operate for faults on the 

low-voltage side of the transformer. Consequently, delayed clearing of faults (i.e., the 

longest clearing time associated with the faults) from the high-voltage side of the 

transformer may occur and subject the transformer to overloads, i.e., through-currents 
Docket No. RM08-13-000 - 130 - 

 

higher than the transformer’s rating. Overcurrent relays used for transformer protection 

have a limited ability to detect these types of faults because they are set above the 

maximum load current155 for entities that set these relays following the IEEE Standards. 

It is for this reason that the ability of the transformer to sustain overloads, i.e., throughcurrents, for the longest clearing time associated with the fault must be verified. 

207. NERC and others state that sub-requirement R1.10 is consistent with IEEE 

Standards C37.91-2008 and C57.109-1993. While the Commission has approved 

Reliability Standards that reference other industry standards,156 Reliability Standard 

PRC-023-1 does not reference either IEEE Standard. Thus, neither IEEE Standard is 

mandatory and enforceable under section 215 of the FPA. 

208. Moreover, we have several concerns about relying on the IEEE Standards to 

address the reliability issue we have identified. First, an entity could provide a facility 

rating that was just within the voluntary requirements in the IEEE Standards, however, 

when setting protection relays according to sub-requirement R1.10, the transformer could 

be subject to currents above its capability as previously described. Second, the IEEE 

Standards may not apply to transformers manufactured before 1993 because the 

155 Section 8.6.1 of IEEE Standard C37.91-2008 states that “[w]hen overcurrent 

relays are used for transformer backup, their sensitivity is limited because they should be 

set above maximum load current.” 

156 E.g., Reliability Standard FAC-003-1, Transmission Vegetation Management 

Program, Footnote 1 (reference to ANSI A300, Tree Care Operations). 
Docket No. RM08-13-000 - 131 - 

guidelines established in C57.109-1993 do not apply to transformers manufactured before 

1993. 

209. We are not persuaded by the ERO’s statement that “a setting of 150 percent of the 

transformer nameplate rating or 115 percent of the highest operator established 

emergency rating will always be less than 200 percent of the transformer forced-cooled 

nameplate rating.” Referring to section 8.6.1 of IEEE Standard C37.91, we point out that 

this statement applies only to the specific configuration where “two or more transformers 

are operated in parallel to share a common load,” which may not be the configuration for 

every transformer on the Bulk-Power System. We also note that section 8.6.1 further 

states that “[r]elays on individual transformers may require pickup levels greater than 

twice the force cooled rating of the transformer to avoid tripping.” Since Requirement 

R1.10 applies to any topology, it must be robust enough to address the reliability issues 

of any topology. Section 8.6.1 of IEEE Standard C37.91 applies only to two or more 

transformers that are operated in parallel. Consequently, we reject NERC’s assertion that 

it is not possible to exceed the rating of a single transformer. 

210. Adopting the NOPR proposal to require entities that implement sub-requirement 

R1.10 to verify that the limiting piece of equipment is capable of sustaining the 

anticipated overload current for the longest clearing time associated with the fault would 

address the Commission’s reliability concerns. Applying protection systems that do not 

respect the actual or verified capability of the limiting facility will result in a degradation 
Docket No. RM08-13-000 - 132 - 

 

of system reliability. In this instance, applying sub-requirement R1.10 without regard to 

the topology and capability of each transformer could cause the transformer to fail. 

Failure of the transformer may not be limited to only the affected transformer, but may 

also affect other Bulk-Power Systems elements in its vicinity, further degrading the 

reliability of the Bulk-Power System. 

211. While NERC explains that sub-requirement R1.10 is intended for specific 

transformer fault protection relays that are set to protect for fault conditions and not 

excessive load conditions, sub-requirement R1.10 does not identify that intent.157 

Additionally, sub-requirement R1.11 of PRC-023-1 establishes criteria for transformer 

overload protection relays that do not comply with sub-requirement R1.10. Because subrequirement R1.11 establishes that the protection must allow an overload for 15 minutes, 

we disagree with WECC that sub-requirement R1.11 addresses the Commission’s 

reliability concern with overloads. 

212. We acknowledge that relays can be set to protect for faults as well as overloads 

and that the operation of relays for fault conditions is much faster than for overload 

conditions. This is because faults need to be removed quickly from the Bulk-Power 

System to limit the severity and spread of system disturbances and prevent possible 

damage to protected elements, while overload relays are designed to operate more slowly, 

157 NERC Petition at 11. 
Docket No. RM08-13-000 - 133 - 

and when applicable, allow time for operators to implement operator control actions to 

mitigate the overloaded facility. Nevertheless, both fault and overload relays are loadresponsive relays. Thus, we agree with those commenters that state that manual 

mitigation of thermal overloads is best left to system operators, who can take appropriate 

actions to support Reliable Operation of the Bulk-Power System. Moreover, because 

both types of relays are load-responsive relays, we disagree with PSEG that the 

Commission’s proposal is beyond the scope of PRC-023-1. 

4. Sub-Requirement R1.12

213. Sub-requirement R1.12 establishes relay loadability criteria when the desired 

transmission line capability is limited by the requirement to adequately protect the 

transmission line. In these cases, the line distance relays are still required to provide 

adequate protection, but the implemented relay settings will limit the desired loading 

capability of the circuit. In its petition, NERC stated that if an essential fault protection 

imposes a more constraining limit on the system, the limit imposed by the fault protection 

is reflected within the facility rating.158 NERC also stated that PRC-023-1 should cause 

no undue negative effect on competition or restrict the grid beyond what is necessary for 

reliability.159 

 158 Id. at 14. 

159 Id. at 27. 
Docket No. RM08-13-000 - 134 - 

a. NOPR Proposal

214. In the NOPR, the Commission expressed concern that sub-requirement R1.12 

allows entities to technically comply with the Reliability Standard without achieving its 

stated purpose. The Commission explained that because entities can set their relays to 

limit the load carrying capability of a transmission line, any line with relays set according 

to sub-requirement R1.12 will not be utilized to its full potential in response to sudden 

increases in line loadings or power swings. The Commission stated this will make the 

natural response of the Bulk-Power System less robust in the case of system disturbances. 

The Commission added that an entity that uses a protection system that requires it to set 

its relays pursuant to sub-requirement R1.12 may not be able to satisfy its reliability 

obligations. Consequently, the Commission requested comments on whether the use of 

such a protection system is consistent with the Reliability Standard’s objectives, and 

whether it should direct a modification that would require entities that employ such a 

protection system to use a different system. 

b. Comments

215. NERC opposes the Commission’s proposal and disagrees with the Commission’s 

assertion that sub-requirement R1.12 allows entities to comply with the Reliability 

Standard without achieving its purpose. NERC states that the Reliability Standard’s 

objectives include ensuring reliable detection of all network faults and preventing 

undesired protective relay operation that interferes with the system operator’s ability to 
Docket No. RM08-13-000 - 135 - 

 

take remedial action. NERC explains that use of sub-requirement R1.12 is restricted to 

cases where adequate line protection cannot be achieved without restricting the 

loadability of the protected transmission element. 

216. NERC and Consumers Energy argue that sub-requirement R1.12 could have 

helped mitigate the August 2003 blackout. NERC and Consumers Energy explain that 

many of the lines that tripped during the blackout were below their emergency rating and 

tripped because of loading limitations imposed by relay settings. NERC and Consumers 

Energy state that these lines tripped without warning to system operators, who were 

unaware of loading limitations imposed by relay settings. NERC and Consumers Energy 

note that sub-requirement R1.12 mandates that facility ratings reflect relay loadability 

limitations and speculate that, if this had been the case on the day of the blackout, system 

operators would have known that they were approaching the relay loadability limitation 

and could have taken mitigating action.160

217. Other commenters share NERC’s view that sub-requirement R1.12 is consistent 

with the Reliability Standard’s purpose.161 Ameren argues that sub-requirement R1.12 

appropriately recognizes that priority must be given to fault detection over loadability 

because undetected faults can result in generation and load instability, outages, and 

160 Consumers Energy at 12-13; NERC Comments at 32. 

161 See also Ameren, Basin, EEI, McDonald, and WECC. 
Docket No. RM08-13-000 - 136 - 

 

increased damage and repair time. Basin states that while sub-requirement R1.12 may 

lead to relay settings that limit a line’s full potential in response to sudden increases in 

line loadings or power swings, it maximizes loadability to the extent possible without 

compromising the primary zone of protection. 

218. Commenters also claim that sub-requirement R1.12 is intended to provide 

acceptable protection for uncommon configurations.162 EEI, WECC, and Consumers 

Energy speculate that sub-requirement R1.12 will most commonly apply to lines with 

three or more terminals, which usually require larger zone 2 settings than two-terminal 

lines. Consumers Energy states that such configurations are actually selected for 

reliability, not cost, such that removal of a line will simultaneously remove other 

components that could not be reliably served in the absence of that line. Oncor states that 

the purpose of sub-requirement R1.12 is to handle those less common system 

configurations where operating the system at the maximum capacity of the equipment in 

the configuration is within the operating range of the protective relay settings to detect 

and clear all faults in the protected configuration. 

219. Some commenters argue that utilities should have the flexibility to decide what is 

necessary for their systems. For example, South Carolina E&G maintains that utilities 

should be allowed to either restrict line loadability for protection or use a different 

162 See, e.g., Consumers Energy, EEI, and Oncor. 
Docket No. RM08-13-000 - 137 - 

 

protection system appropriate for the particular situation. TVA argues that a utility 

should be able to establish facility ratings based on thermal or relay limits, and that as 

long as facility ratings are applied in system studies correctly (and such studies show no 

violations), a utility should not be required to change its protective schemes to allow a 

higher facility rating based on thermal limits. 

220. TAPS describes sub-requirement R1.12 as an example of NERC and industry 

experts properly exercising flexibility to balance a number of reliability factors, including 

cost, as the Commission recognized is appropriate in Order No. 672. TAPS reiterates 

that in Order No. 672 the Commission stated that a proposed Reliability Standard need 

not reflect the optimal method, or “best practice,” for achieving its reliability goal 

without regard to implementation cost or historical regional infrastructure design.163 

TAPS argues that in assessing whether the Reliability Standard achieves its reliability 

goal efficiently and effectively, the Commission should give due weight to NERC’s 

balancing of competing factors. TAPS also claims that the Commission’s proposal to 

require a broad change of equipment is expensive and “run[s] afoul” of sections 

215(a)(3)164 and (i)(2) of the FPA, which limit Reliability Standards that require 

expansion of facilities. 

163 TAPS at 26 (citing Order No. 672, FERC Stats. & Regs. ¶ 31,204 at P 328). 

164 16 U.S.C. 824o(a)(3). 
Docket No. RM08-13-000 - 138 - 

221. APPA states that the Commission’s proposal appears to require NERC to prohibit 

protection systems that would require the use of sub-requirement R1.12, effectively 

writing sub-requirement R1.12 out of the Reliability Standard. APPA argues that the 

Commission is proposing to direct NERC to adopt a specific modification that may not 

be the best or most efficient way to address the Commission’s concerns. APPA states 

that it agrees with the Commission raising the issue to the extent that the Commission is 

concerned about the adverse impact of sub-requirement R1.12 on Available Transfer 

Capability. APPA contends, however, that having raised the issue, the Commission 

should direct NERC as the ERO to develop solutions rather than dictate a solution in the 

first instance. 

222. The PSEG Companies argue that it is impractical to require entities to replace 

existing impedance relay systems without evidence that their continued use will have a 

negative reliability impact. The PSEG Companies contend that protection systems 

should be replaced only if reliability studies show that the limits imposed on the system 

by the use of sub-requirement R1.12 will truly impede reliability. Oncor argues that a 

modification that would require entities that employ impedance relays to replace them 

with a current differential or pilot wire relay system that is immune to load or stable 

power swings would eliminate the valuable backup feature of the impedance relay and 

actually reduce the reliability of the grid serving the atypical configuration. 
Docket No. RM08-13-000 - 139 - 

223. EEI and WECC assert that sub-requirement R1.12 can reasonably be interpreted as 

the first step in implementing the Commission’s proposal to limit the reach of zone 

3/zone 2 relays.165 EEI and WECC explain that sub-requirement R1.12 imposes a 

maximum reach for distance relays of 125 percent of the apparent length of the protected 

line, which allows relays to dependably detect faults. EEI and WECC add that use of 

sub-requirement R1.12 may prevent entities from using time-delayed, over reaching zone 

3 relays as remote backup protection, unless they employ other load limiting relay 

features. EEI and WECC argue that even with this single possible limitation, this 

loadability method is consistent with the Reliability Standard’s objectives. 

c. Commission Determination

224. We decline to adopt the NOPR proposal. After further consideration, we think 

that it is incumbent on entities that implement sub-requirement R1.12 to ensure that they 

implement it in a manner that is consistent and coordinated with the Requirements of 

existing Reliability Standards and that achieves performance results consistent with their 

obligations under existing Standards. While we are not adopting the NOPR proposal, we 

direct the ERO to document, subject to audit by the Commission, and to make available 

for review to users, owners and operators of the Bulk-Power System, by request, a list of 

those facilities that have protective relays set pursuant sub-requirement R1.12. We 

 165 EEI at 25; WECC at 5-6. 
Docket No. RM08-13-000 - 140 - 

 

believe that this transparency will allow users, owners, and operators of the Bulk-Power 

System to know which facilities have protective relay settings, implementing R1.12, that 

limit the facility’s capability. 

225. We also disagree with commenters who argue that the few instances where a 

protection system implements sub-requirement R1.12 are not a threat to the reliability of 

the Bulk-Power System unless they have been declared critical circuits. Protective relays 

on Bulk-Power Systems elements are an integral part of Reliable Operation.166 Any 

instance of a protection system that does not ensure Reliable Operation is a reliability 

concern, not only to prevent and limit the severity and spread of disturbances, but also to 

prevent possible damage to protected elements.167 

226. We also disagree with EEI’s and WECC’s assertion that sub-requirement R1.12 

can reasonably be interpreted as the first step in implementing the Commission’s 

proposal to limit the reach of zone 3/zone 2 relays.168 Sub-requirement R1.12 establishes 

loadability criteria for distance relays when the desired transmission line capability is 

limited by the requirement to protect the transmission line, and not explicitly for the 

166 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1435. 

167 Id. 

168 As discussed previously, the Commission has decided not to adopt the NOPR 

proposal for establishing a maximum allowable reach for the application of zone 3/zone 2 

relays applied as remote circuit breaker failure and backup protection upon consideration 

of comments. 
Docket No. RM08-13-000 - 141 - 

application of zone 3/zone 2 distance relays applied as remote circuit breaker failure and 

backup protection. As discussed previously, the Commission proposed to establish a 

maximum allowable reach for such relays because that their large reaches make the 

relays susceptible to tripping from load. 

G. Requirement R2

227. Requirement R2 states that entities that use a circuit with the protective relay 

settings determined by the practical limitations described in sub-requirements R1.6 

through R1.9, R1.12, or R1.13 must use the calculated circuit capability as the circuit’s 

facility rating. The entities also must obtain the agreement of the planning coordinator, 

transmission operator, and reliability coordinator as to the calculated circuit capability. 

The Commission did not make any proposal regarding Requirement R2. 

1. Comments

228. ERCOT and IRC state that the Commission should clarify that the “agreement” 

contemplated in Requirement R2 only means that the entity calculating the circuit 

capability is required to provide the circuit capability to the relevant functional entities. 

ERCOT notes that because it is the planning coordinator, transmission operator and 

reliability coordinator in the ERCOT region, it would be responsible for reviewing and 

approving the calculated circuit capabilities under Requirement R2. ERCOT states that it 

lacks the necessary analysis tools and data (e.g., conductor sag software and transmission 

design data to determine emergency ratings) to provide an informed opinion on the 
Docket No. RM08-13-000 - 142 - 

circuit capabilities calculated by transmission owners, generator owners, or distribution 

owners pursuant to Requirement R2. ERCOT argues that the entities that own the 

facilities are in the best position to establish those limits, and that planning coordinators, 

transmission operators, and reliability coordinators should not be required to approve 

them. ERCOT contends that planning coordinators, transmission operators, and 

reliability coordinators should merely be made aware of the limits in order to respect 

them while executing their duties. IRC makes the similar claim that the term 

“agreement” in Requirement R2 requires only a data check or confirmation, such that 

planning coordinators, transmission operators, and reliability coordinators must simply 

agree that they will use the circuit capability provided by the transmission owner, 

generator owner, or distribution owner. IRC argues that this interpretation is consistent 

with both FAC-008-1, which requires transmission and generator owners to establish 

facility rating methodologies for their facilities and provide them to reliability 

coordinators, transmission operators, transmission planners, and planning authorities, and 

FAC-009-0, which requires transmission and generator owners to provide the resultant 

facility ratings to the same entities. 

2. Commission Determination

229. We do not agree with ERCOT and IRC that an entity’s obligation to obtain the 

“agreement” of the planning coordinator, transmission operator, or reliability coordinator 

with the calculated circuit capability only means that the entity calculating the circuit 
Docket No. RM08-13-000 - 143 - 

capability is required to provide the circuit capability to the relevant functional entities. 

We interpret the language “shall obtain the agreement” in Requirement R2 to require that 

the entity calculating the circuit capability must reach an understanding with the relevant 

functional entity that the calculated circuit capability is capable of achieving the 

reliability goal of PRC-023-1. Since PRC-023-1 is intended to ensure that protective 

relay settings do not limit transmission loadability or interfere with system operators’ 

ability to take remedial action to protect system reliability, and to ensure that relays 

reliably detect all fault conditions and protect the electrical network from these faults, we 

expect the agreement to center around achieving these purposes. 

H. Requirement R3 and its Sub-Requirements

230. Requirement R3 directs planning coordinators to identify which sub-200 kV 

facilities are critical to the reliability of the bulk electric system and therefore subject to 

Requirement R1.169 Sub-requirement R3.1 directs planning coordinators to have a 

process to identify critical facilities. Sub-requirement R3.1.1 specifies that the process 

must consider input from adjoining planning coordinators and affected reliability 

coordinators. Sub-requirements R3.2 and R3.3 direct planning coordinators to maintain a 

 169 As proposed by NERC, Requirement R3 directs planning coordinators to 

identify the 100 kV-200 kV facilities that should be subject to Requirement R1. As we 

have explained, in this Final Rule we direct that the ERO revise Requirement R3 so that 

planning coordinators also identify sub-100 kV facilities that should be subject to the 

Reliability Standard. 
Docket No. RM08-13-000 - 144 - 

list of critical facilities and provide it to reliability coordinators, transmission owners, 

generator owners, and distribution providers within 30 days of establishing it, and within 

30 days of making any change to it. 

1. Role of the Planning Coordinator

 a. Comments

231. ERCOT argues that the Commission should follow the example of the Critical 

Infrastructure Protection (CIP) Reliability Standards and direct the ERO to make facility 

owners, rather than planning coordinators, responsible for identifying critical sub-200 kV 

facilities and for maintaining and distributing the critical facilities list. ERCOT contends 

that while planning coordinators and other functional entities must receive all relevant 

information about facilities in their region, facility owners have the right and obligation 

to make criticality determinations about their facilities. ERCOT argues that the CIP 

Reliability Standards support its position, as they require facility owners to identify 

critical assets. 

232. ERCOT also requests confirmation that sub-requirement R3.1.1 does not apply to 

the ERCOT region because it is not synchronously interconnected with any other control 

area and because ERCOT is the only planning coordinator and reliability coordinator 

within the region. 
Docket No. RM08-13-000 - 145 - 

b. Commission Determination

233. We disagree with ERCOT and will not direct the ERO to make facility owners 

responsible for identifying critical sub-200 kV facilities or for maintaining and 

distributing the critical facilities list. We also reject ERCOT’s comparison between 

PRC-023-1 and the CIP Reliability Standards. Facility owners are responsible for 

maintaining only their own facilities. Planning coordinators, on the other hand, are 

charged with assessing the long-term reliability of their planning authority areas.170 

Consequently, planning coordinators are better prepared and equipped to make the 

comprehensive criticality determinations for their areas for the purposes of PRC-023-1. 

We thus agree with the ERO that planning coordinators are better suited to make the 

criticality determinations for the purposes of PRC-023-1. 

234. Finally, while we acknowledge that ERCOT is not synchronously interconnected 

with any other control area and that it is the only planning coordinator and reliability 

coordinator in its region, we clarify that any request for a regional exemption from 

PRC-023-1 is an applicability matter that must be raised in the Reliability Standards 

development process and included in a modified Reliability Standard.171 Consequently, 

Requirement R3 and its sub-requirements apply to ERCOT. 

 170 See NERC Function Model, Version 3 at 14. 

171 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 1125. 
Docket No. RM08-13-000 - 146 - 

2. Sub-Requirement R3.3

 a. NOPR Proposal

235. The Commission proposed to direct the ERO to add Regional Entities to the list of 

entities that receive the critical facilities list pursuant to sub-requirement R3.3. 

b. Comments

236. NERC and WECC agree with the Commission that the Regional Entity should 

receive the critical facilities list. EEI acknowledges that the Commission’s proposal may 

have merit, but opposes a modification. EEI explains that the Regional Entity can 

already request the data from planning authorities and reliability coordinators at any time, 

and argues that it is not necessary to formalize the process. 

c. Commission Determination

237. We adopt the NOPR proposal and direct the ERO to modify the Reliability 

Standard to add the Regional Entity to the list of entities that receive the critical facilities 

list. The Regional Entity must know which facilities in its area have been identified as 

operationally significant and could contribute to cascading outages and the loss of load. 

Additionally, providing Regional Entities with the critical facilities list will aid in the 

overall coordination of planning and operational studies among planning coordinators, 

transmission owners, generator owners, distribution providers, and Regional Entities. As 

with our other directives in this Final Rule, we do not prescribe this specific change as an 

exclusive solution to our reliability concerns regarding sub-requirement R3.3. As we 
Docket No. RM08-13-000 - 147 - 

have stated, the ERO can propose an alternative solution that it believes is an equally 

effective and efficient approach to addressing the Commission’s reliability concerns.172 

I. Attachment A

238. Attachment A of the Reliability Standard contains three sections: (1) a nonexhaustive list of load-responsive relays subject to the Standard; (2) a statement that outof-step blocking protective schemes are subject to the Standard and shall be evaluated to 

ensure that they do not block trip for fault during the loading conditions defined within 

the Standard’s requirements; and (3) a list of protective systems that are expressly 

excluded from the Standard’s requirements. In the NOPR, the Commission expressed 

concerns about sections 2 and 3. 

1. Section 2: Evaluation of Out-of-Step Blocking Schemes

239. Section 2 of Attachment A states that the “[Reliability Standard] includes out-ofstep blocking schemes which shall be evaluated to ensure that they do not block trip for 

faults during the loading conditions defined within the requirements.” 

a. NOPR Proposal

240. In the NOPR, the Commission stated that since the ERO intends to require the 

evaluation of out-of-step blocking applications, language to this effect should be included 

in PRC-023-1 as a Requirement. To this end, the Commission proposed to direct the 

 172 Id. P 186. 
Docket No. RM08-13-000 - 148 - 

ERO to add section 2 of Attachment A to PRC-023-1 as an additional Requirement with 

the appropriate violation risk factor and violation severity level assignments. 

b. Comments

241. NERC agrees that the proposed modification is appropriate and proposes to 

implement it through the full Reliability Standards development process in the next 

modification of PRC-023-1. In the meantime, NERC requests that the Commission 

approve Attachment A as currently written.173

242. WECC asserts that the Commission’s proposal is reasonable because the 

obligation to evaluate out-of-step blocking schemes is part of PRC-023-1, but carries no 

penalty without a violation risk factor and violation severity level. WECC suggests that 

the Commission take the same approach with respect to out-of-step tripping (section 1.2). 

WECC explains that without appropriate load supervision, out-of-step tripping may 

subject circuit breakers to excessive over-voltages, if it occurs at all. 

243. Dominion, EEI, and Oncor disagree with the Commission’s proposal. Rather than 

make it a Requirement, Dominion argues that the statement about out-of-step blocking 

schemes should be removed from PRC-023-1 and included in a Reliability Standard that 

addresses stable power swings. EEI asserts that section 2 appropriately appears in 

Attachment A because Attachment A identifies the types of transmission line relays and 

 173 See also Duke and IESO/Hydro One. 
Docket No. RM08-13-000 - 149 - 

relay schemes that are subject to the Reliability Standard, and out of step blocking relays 

are “transmission line relays” addressed in Requirement R1. Oncor argues that section 2 

is already a requirement because it is in an attachment instead of an appendix. 

c. Commission Determination

244. We adopt the NOPR proposal and direct the ERO to include section 2 of 

Attachment A in the modified Reliability Standard as an additional Requirement with the 

appropriate violation risk factor and violation severity level.

245. EEI correctly states that Attachment A is a compilation of the types of 

transmission line relays and relay schemes that are subject to PRC-023-1, and that section 

2 specifies that out-of-step blocking schemes are subject to it. However, section 2 also 

creates an obligation to evaluate out-of-step blocking schemes to ensure that they do not 

block trip for faults during the loading conditions defined within the Reliability 

Standard’s Requirements. This is an obligation that is not stated in, or referenced by, any 

Requirement in the Reliability Standard. Consequently, this obligation is not currently 

associated with a violation risk factor or violation severity level.

246. Although the obligation to evaluate out-of-step blocking schemes is currently not 

stated in a Requirement, it nevertheless remains an obligation imposed on entities by 

PRC-023-1 because it is a part of Attachment A and therefore a part of PRC-023-1. 

Consequently, we clarify that entities must comply with this obligation while the ERO 

modifies PRC-023-1 to include it as a Requirement. 
Docket No. RM08-13-000 - 150 - 

247. We disagree with Dominion’s suggestion that the Commission direct the ERO to 

remove section 2 from PRC-023-1 and include it in a Reliability Standard that addresses 

stable power swings. It is appropriate to include section 2 as a Requirement in 

PRC-023-1 because out-of-step blocking schemes must be allowed to trip for faults 

during the loading conditions defined within PRC-023-1. Otherwise, faults that occur 

during a power swing may result in system instability if not cleared. 

248. Finally, we will not direct the ERO to make section 1.2 into a Requirement as 

WECC suggests. Section 1 of Attachment A is a non-exhaustive list of relays and 

protection systems that are subject to Attachment A; unlike section 2, section 1 does not 

create substantive obligations that are neither stated in nor referenced by the 

Requirements. Section 1.2 merely lists out-of-step tripping systems as one of the systems 

that are subject to the Reliability Standard and must be set pursuant to Requirement R1. 

2. Section 3: Protection Systems Excluded from the Reliability 

Standard

249. Section 3 lists certain protection systems that are excluded from the requirements 

of PRC-023-1. These systems are specified in sections 3.1 through 3.9. 
Docket No. RM08-13-000 - 151 - 

a. NOPR Proposal

250. In the NOPR, the Commission stated that it could not determine whether the 

exclusions in section 3 are justified because NERC did not provide the technical rationale 

behind any of the exclusions.174 

251. The Commission also raised specific concerns about section 3.1, which excludes 

from the Reliability Standard’s requirements relay elements that are enabled only when 

other relays or associated systems fail, such as those overcurrent elements enabled only 

during loss of potential conditions or elements enabled only during the loss of 

communications. The Commission expressed concern that section 3.1 could be 

interpreted to exclude certain protection systems that use communications to compare 

current quantities and directions at both ends of a transmission line, such as pilot wire 

protection or current differential protection systems supervised by fault detector relays. 

The Commission explained that if supervising fault detector relays are not subject to the 

Reliability Standard, and they are set below the rating of the protected element, the loss 

of communications and heavy line loading conditions that approach the line rating would 

cause them to operate and unnecessarily disconnect the line; adjacent transmission lines 

with similar protection systems and settings would also operate unnecessarily, resulting 

in cascading outages. The Commission requested comments, therefore, on whether the 

 174 The exclusion of protection systems intended for the detection of ground fault 

conditions appears to be unnecessary because these systems are not load-responsive. 
Docket No. RM08-13-000 - 152 - 

exclusions in section 3 are technically justified and whether it should direct the ERO to 

modify PRC-023-1 by deleting specific sections in section 3. The Commission also 

requested comment on whether it should direct the ERO to modify section 3.1 to clarify 

that it does not exclude from the requirements of PRC-023-1 pilot wire protection or 

current differential protection systems supervised by fault detector relays.175

b. Comments

252. While NERC acknowledges that specific justification should be included for those 

protection systems that ultimately remain excluded from the Reliability Standard’s 

requirements, NERC opposes removing any of the exclusions.176

253. With respect to section 3.1, NERC does not share the Commission’s concern and 

urges it not to direct the removal of supervising fault detector relays from the list of 

exclusions. NERC explains that section 3.1 excludes elements that: (1) do not respond 

to load current; (2) are in use only during very short periods of time to address short-term 

conditions; or (3) supervise operation of relay elements that themselves are subject to the 

 175 The Commission also noted that section 3.5 excludes from the requirements of 

PRC-023-1 “relay elements used only for [s]pecial [p]rotection [s]ystems applied and 

approved in accordance with NERC Reliability Standards PRC-012 through PRC-017.” 

Since PRC-012-0, PRC-013-0 and PRC-014-0 are currently proposed Reliability 

Standards pending before the Commission, the particular relay elements they involve 

remain subject to PRC-023-1 until the relevant Standards are approved by the 

Commission. Order No. 693-A, 120 FERC ¶ 61,053 at P 138. 

176 NERC Comments at 35. 
Docket No. RM08-13-000 - 153 - 

Reliability Standard. NERC explains that if the supervised relay element itself does not 

operate in these cases, the operation of the supervising element should have no impact on 

reliability. NERC asserts that if a communications system is lost, the transmission 

element must be protected and may need to be tripped for low magnitude faults 

approaching load current. NERC argues that it is preferable to trip one line for loss of 

communications than not trip at all, thereby causing mis-coordination and/or stability 

problems. NERC adds that the failure of a communications-based protection system is 

typically an isolated event. 

254. EEI speculates that the intent behind specifically excluding overcurrent elements 

enabled only during loss of potential conditions and elements enabled only during a loss 

of communications (the specific examples listed in section 3.1) is to exclude relay system 

failures that, for normal utility practice, would result in either emergency call outs and 

repairs or next-day call outs and repairs. EEI concludes that these failures are rare 

enough to have a limited impact on the Bulk-Power System. 

255. EEI and Ameren support section 3.1 as technically justified because it allows 

transmission lines to remain in-service with a level of fault protection while the failure 

that required activation of the section 3.1 relays is repaired, and that the alternative would 
Docket No. RM08-13-000 - 154 - 

tate. 

 

be to take the lines or buses out of service.177 Ameren cautions that this alternative 

would put the system in a less reliable N-1 or N-many s

256. EEI adds that many long transmission lines proposed to support the creation of the 

national grid will require backup protection for the types of failures discussed in section 

3.1. EEI explains that, for very long lines, the fault currents can be below rated 

continuous capability without the 150 percent margin, and that simple schemes are 

required for the small periods of time when the backup protection will be in-service 

following a loss of potential conditions or communications. EEI contends that these 

exceptions only impact one facility at a time and do not present more risk than removing 

the facility. 

257. Exelon, Consumers Energy, and IESO/Hydro One also claim that the exclusions in 

section 3.1 are justified. Exelon asserts that the Reliability Standard’s goal is to address 

protective relays that have a history of contributing to cascades, and that relays enabled 

only when other relays or associated systems fail are extremely unlikely to be a factor in 

a disturbance because they are enabled so infrequently. Consumers Energy cautions that 

the relays excluded in section 3.1 must be able to respond to relay failures without regard 

to relay loadability; otherwise, there is a risk that faults will not be cleared and there will 

be cascading outages. IESO/Hydro One argue that the Commission should approve 

177 EEI at 27-28; Ameren at 15. 
Docket No. RM08-13-000 - 155 - 

 

section 3.1 because the relays it excludes are incapable of independently opening the 

circuit breaker; that is, they require the action of other relays. 

258. TAPS argues that NERC should reconsider section 3.1 because the exclusion of 

relay elements enabled only when other relays or associated systems fail depends on the 

successful operation of a potential source (potential transformer or capacitor coupled 

voltage transformer (CCVT)) or a communication system.178 TAPS explains that the 

TPL Reliability Standards require planners to plan the system as if a potential source or 

communication system has failed (e.g., TPL-003-0). Although potential sources and 

communication systems fail infrequently, TAPS states that it might be consistent with the 

TPL Standards for NERC to reconsider the balance of these factors. TAPS argues, 

however, that the Commission should not require NERC to eliminate section 3.1. 

259. In general, commenters contend that the rest of the exclusions in section 3 have a 

sound technical basis. Basin argues that the exclusions address protection systems that 

have no significant impact on the reliability of the bulk electric system, and suggests that 

the Commission consider the following criteria in determining whether a system should 

be subject to PRC-023-1: (1) the frequency with which that system is enabled; (2) the 

probability that the system will be activated when it is enabled; and (3) the effects that the 

178 TAPS, Attachment 1 at 17.
Docket No. RM08-13-000 - 156 - 

 

protection system will have on the Bulk-Power System when it is activated.179 Basin 

argues that protection systems that have a low probability of being activated when 

enabled should be excluded from the Reliability Standard. Likewise, those that, when 

activated, have an inconsequential effect on system stability should also be excluded 

from the Reliability Standard. The PSEG Companies argue that PRC-023-1 reasonably 

balances risks with the potential expenditure of substantial and costly changes to 

protection systems.180 

260. Exelon and Consumers Energy argue that section 3.2, which excludes relays that 

are designed to detect ground fault conditions, is justified because such relays have no 

significant history of contributing to cascades. Consumers Energy claims that it would be 

a waste of resources to identify, study, and document the behavior of devices intended for 

the detection of ground faults, when such devices are immune to tripping for load 

currents. 

261. Duke asserts that it is unclear whether section 3.3, which excludes protection 

systems intended for protection during stable power swings, is meant for tripping or to 

block tripping. Duke states that if the protection is to block tripping, the exclusion is in 

179 Basin at 12-13. 

180 PSEG Companies at 12. 
Docket No. RM08-13-000 - 157 - 

 

conflict with section 2 of Attachment A, as many relays use the same logic to block for 

out-of-step conditions and for stable power swings. 

262. Exelon states that the relays identified in section 3.5, which excludes relays used 

for special protection systems applied and approved in accordance with Reliability 

Standards PRC-012 through PRC-017, are designed along with specific relay settings to 

assure that a given power system meets NERC performance requirements. Consumers 

Energy asserts that these relay systems are intended for a specific set of conditions and 

already undergo a stringent review, such that additional review under PRC-023-1 is 

unnecessary and creates the risk that a special protection system approved under 

PRC-012 through PRC-017 may be found non-compliant under PRC-023-1. Dominion 

adds that relay elements used only for special protection systems applied and approved in 

accordance with PRC-012 through PRC-017 do not present a risk to the reliability of the 

grid because the instances in which they operate are rare events that are addressed and 

corrected in a timely manner.181 

263. TAPS argues that the exclusions in sections 3.2 through 3.8 are designed to ensure 

that PRC-023-1 applies where it is needed to address loadability concerns, but does not 

interfere with relays that are not tripped by load current. TAPS adds that section 3.9, 

which excludes relay elements associated with DC converter transformers, is justified 

181 Dominion at 8. 
Docket No. RM08-13-000 - 158 - 

because the output of generators and DC line converters is not changed significantly with 

the loss of other facilities.182 

c. Commission Determination

264. After further consideration, and in light of the comments, we will not direct the 

ERO to remove any exclusion from section 3, except for the exclusion of supervising 

relay elements in section 3.1. Consequently, we direct the ERO to revise section 1 of 

Attachment A to include supervising relay elements on the list of relays and protection 

systems that are specifically subject to the Reliability Standard. As with our other 

directives in this Final Rule, we do not prescribe this specific change as an exclusive 

solution to our reliability concerns regarding the exclusion of supervising relay elements. 

As we have stated, the ERO can propose an alternative solution that it believes is an 

equally effective and efficient approach to addressing the Commission’s reliability 

concerns.183 

265. Supervising elements ensure that a protection system is secure and does not 

operate when it should not operate. When a supervising relay is in place, it acts as a 

check on the supervised protection system because both must operate to trip a facility. If 

a supervising relay is set below the rating of the line, high loading conditions will cause it 

 182 TAPS at 27-28. 

183 Order No. 693, FERC Stats. & Regs. ¶ 31,242 at P 186. 
Docket No. RM08-13-000 - 159 - 

 

to be “picked-up,” i.e., continuously energized and ready to operate. When this occurs, 

the supervising relay will no longer be able to act as a check on the other protection 

system because the supervising relay will already have registered that it should operate. 

At that point, the supervising relay will be waiting for the supervised relay to become 

energized before tripping the protected facility.184 

266. For example, current differential protection systems use communication systems 

to transmit and compare information between relays located at both terminals and to 

initiate the high-speed tripping of a facility when the difference of currents at the sending 

end and receiving end exceeds a threshold setting usually set at a small fraction of the 

normal line loading. Since these protection systems are dependent on communication 

systems, the protected facility will trip if communication is lost, even when the line 

continues to carry its normal load current, because the difference of the currents as seen 

at either end will be the load current which is much larger than the threshold setting. 

Consequently, overcurrent relays are typically used as supervising relays to prevent the 

protected facility from tripping if communication is lost. However, if the supervising 

relays are energized due to loading conditions, and then communication is lost, the 

184 It works like an “and” condition (0 + 0 = no trip line, 1 + 1 = trip line, 1 + 0 = 

no trip line). For a supervising relay like a fault detector to be always “picked up” means 

that the relay is energized (it is always a “1”) and is waiting for another relay to also 

become energized before tripping a facility. 
Docket No. RM08-13-000 - 160 - 

 

current differential protection system will operate in the absence of a fault and the 

protected facility will trip. 

267. NERC asserts that it is preferable to trip one line for loss of communications than 

not trip at all, thereby causing mis-coordination and/or stability problems. We disagree. 

Protective relays should not operate during non-fault conditions. The tripping of 

facilities for non-fault conditions, like NERC describes, or in the case of the August 2003 

blackout is not desirable system performance. 

268. We also disagree with IESO/Hydro One’s assertion that the exclusion of 

supervising relays from PRC-023-1 is appropriate because such relays are not capable of 

independently opening the circuit breaker. While a supervising relay is not designed to 

independently trip a facility by initiating the opening of the circuit breaker, if that relay is 

picked up and energized during non-fault conditions, it is no longer capable of ensuring 

the security of a protection system and may result in the unnecessary tripping of the 

facility it is protecting. As we explained, if supervising relays are not subject to the 

Reliability Standard, and are set below the rating of the protected element, the loss of 

communications and heavy line loading conditions that approach the line rating would 

cause them to operate and unnecessarily disconnect the line.185 A more recent example is 

an event that occurred on June 27, 2007 where 138 kV transmission lines in the NPCC 

185 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 79. 
Docket No. RM08-13-000 - 161 - 

 

region resulted in sequential tripping of the four 138 kV cable-circuits. The event 

resulted in the interruption of service to about 137,000 customers as well as the loss of 

five generators and six 138 kV transmission lines. This event is the type of situation that 

PRC-023-1 is intended to prevent, and illustrates why we must direct the ERO to modify 

Attachment A to include supervising relays. 

269. Although we do not direct the ERO to remove section 3.1 from the list of excluded 

protection systems, we find it necessary to address some comments made in the context 

of the Commission’s proposal. For example, we disagree with those commenters that 

suggest that the Commission should approve section 3.1 because it excludes from the 

Reliability Standard’s scope relays and protection systems that rarely operate. These 

commenters appear to suggest that protection systems that rarely operate do not pose a 

risk to the reliability of the Bulk-Power System. We disagree. A protective relay, as an 

integral part of the Bulk-Power System, must be dependable and secure; it must operate 

correctly when required to clear a fault and refrain from operating unnecessarily, i.e., 

during non-fault conditions or for faults outside of its zone of protection, regardless of 

how many times the relay must actually operate.186 Relays must meet this expectation to 

contribute to ensuring Reliable Operation of the Bulk-Power System. Consequently, the 

186 These fundamental objectives for protection systems are consistent if not 

identical with the ones stated in NERC Planning Standards III: System Protection and 

Control, at 43: Dependability – a measure of certainty to operate when required, Security 

– a measure of certainty not to operate falsely. 
Docket No. RM08-13-000 - 162 - 

notion that any specific relay should be excluded from the Reliability Standard’s scope 

because it may operate only on rare occasions is inconsistent with the fundamental 

principles that make protective relays an integral part of ensuring Reliable Operation. 

270. We also disagree with Ameren’s assertion that removing section 3.1 from the list 

of exclusions would put the Bulk-Power System in a “less reliable N-1state.” As we 

discuss above, if supervising relays that are used in current differential schemes are 

excluded from PRC-023-1 and set much below the line rating, they will trip the protected 

lines inadvertently following the loss of communication system forming part of the 

protection system. 

271. Finally, Duke asserts that section 3.3 is ambiguous with respect to whether it 

excludes protection meant for tripping or to block tripping, and that if it excludes 

protection meant to block tripping, it is in conflict with section 2 because many relays use 

the same logic to block for out-of-step conditions and for stable power swings. We 

clarify that we do not find a conflict between section 3.3, which excludes from the 

Reliability Standard’s scope any protection system intended for protection during stable 

power swings, and section 2, which ensures that out-of-step blocking schemes do not 

block tripping during the loading conditions defined within PRC-023-1. 

272. Out-of-step schemes, blocking and tripping, are generally associated with power 

swing protection applications. Out-of-step tripping schemes allow controlled tripping 

during loss of synchronism during unstable power swings while out-of-step blocking 
Docket No. RM08-13-000 - 163 - 

schemes block tripping during stable power swings. Because out-of-step tripping relays 

are supervised by load-responsive overcurrent relays, its applicability to the requirements 

of PRC-023-1 is appropriate. Because the reliability objective of Requirement R1 is to 

set protective relays while “maintaining reliable protection of the bulk-electric system for 

all fault conditions,” as previously determined, out-of-step blocking schemes must allow 

tripping for faults during the loading conditions defined within PRC-023-1. Thus, the 

reliability goal of the two schemes for the purposes of PRC-023-1 is different, and 

consequently, we find no conflict within the Standard. 

J. Effective Date

273. NERC proposed the following effective dates for Requirements R1 and R2: 

(1) the beginning of the first calendar quarter following applicable regulatory approvals 

for all transmission lines and transformers with low-voltage terminals operated/connected 

at and above 200 kV, except for switch-on-to fault-schemes; (2) the beginning of the first 

calendar quarter 39 months after applicable regulatory approvals for all transmission lines 

and transformers with low-voltage terminals operated/connected between 100 kV and 

200 kV, including switch-on-to fault-schemes187; and (3) 24 months from notification by 

the planning coordinator that, pursuant to the “add in” approach, a facility has been added 

 187 “Switch-on-to-fault schemes” are protection systems designed to trip a 

transmission line breaker when the breaker is closed into a fault. Because the current 

fault detectors for these systems must be set low enough to detect “zero-voltage” faults, 

i.e., close-in, three-phase faults, these systems may be susceptible to operate on load. 
Docket No. RM08-13-000 - 164 - 

to the planning coordinator’s list of critical facilities. For Requirement R3, NERC 

proposed an effective date of 18 months following applicable regulatory approvals. 

274. NERC also proposed to include a footnote (exceptions footnote) to the “Effective 

Dates” section honoring temporary exceptions from enforcement actions approved by the 

NERC Planning Committee before NERC proposed the Reliability Standard.188 

1. NOPR Proposal

275. In the NOPR, the Commission proposed to approve NERC’s implementation plan 

for facilities operated at and above 200 kV. In light of its applicability proposals, the 

Commission proposed to reject the rest of NERC’s implementation plan and require, for 

all sub-200 kV facilities, an effective date of 18 months following applicable regulatory 

approvals. The Commission also proposed to direct NERC to remove the exceptions 

footnote, explaining that discussions about potential enforcement actions are best left out 

 188 The footnote states: 

Temporary Exceptions that have already been approved by the NERC 

Planning Committee via the NERC System and Protection and Control 

Task Force prior to the approval of this [Reliability Standard] shall not 

result in either findings of non-compliance or sanctions if all of the 

following apply: (1) the approved requests for Temporary Exceptions 

include a mitigation plan (including schedule) to come into full compliance, 

and (2) the non-conforming relay settings are mitigated according to the 

approved mitigation plan. 
Docket No. RM08-13-000 - 165 - 

of a Reliability Standard and instead handled by NERC’s compliance and enforcement 

program.189 

2. Comments on Effective Date Proposals 

276. In general, commenters support the Commission’s proposal to adopt the effective 

date proposed by NERC for facilities operated at and above 200 kV, but overwhelmingly 

oppose the Commission’s proposal for an 18 month effective date for sub-200 kV 

facilities, regardless of whether the Commission directs the ERO to adopt the “rule out” 

approach or approves NERC’s “add in” approach.190 Commenters generally argue that 

the Commission should adopt NERC’s proposal of an effective date of the beginning of 

the first calendar quarter 39 months after applicable regulatory approvals for 100 kV-200 

kV facilities. 

277. NERC argues that planning coordinators will require at least 18 months to identify 

the 100 kV-200 kV facilities that should be subject to the Reliability Standard, and 

possibly an additional 18 to 24 months to complete any design and construction changes 

necessary to comply with the Standard. Consumers Energy, EEI, and Oncor offer similar 

estimates. 

 189 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 85-86. 

190 Commenters argue that a “rule out” approach would require a much longer 

implementation period, with estimates of up to 12 years. 
Docket No. RM08-13-000 - 166 - 

278. APPA argues that NERC’s implementation plan gives planning coordinators the 

time necessary to perform in-depth studies to identify which facilities are critical to the 

reliability of the bulk electric system, and gives affected entities the time to make any 

necessary costly upgrades. APPA adds that only a limited number of experienced 

industry experts and consultants will be available to assist entities in complying with the 

Reliability Standard, and speculates that their time will be in high demand. 

279. TAPS observes that Order No. 672 recognizes that implementation timelines must 

balance any urgency in the need to implement a Reliability Standard with the 

reasonableness of the time allowed for those who must comply to develop the necessary 

procedures, software, facilities, staffing or other relevant capability.191 TAPS argues that 

the Commission should give due weight to NERC’s expert assessment of that balance 

and adopt the effective dates proposed by NERC. 

3. Comments on Exceptions Footnote

280. EEI argues that the Commission’s proposal to direct the ERO to remove the 

exceptions footnote is too prescriptive given the Commission’s statutory role in the 

Reliability Standard development process. EEI argues that the Commission has gone 

 191 TAPS at 29 (citing Order No. 672, FERC Stats. & Regs. ¶ 31,204 at P 333). 
Docket No. RM08-13-000 - 167 - 

much farther than identifying its concern because its proposal does not allow for the ERO 

to develop equally effective alternatives.192 

281. Oncor and Consumers Energy agree with the Commission’s proposal. Oncor 

argues that the need for the temporary exemption has expired and therefore should be 

removed from the Reliability Standard. 

4. Commission Determination

282. We decline to fully adopt the NOPR proposal and approve all of NERC’s 

proposed effective dates, including its proposal of 39 months from the beginning of the 

first calendar quarter after applicable regulatory approvals for 100 kV-200 kV facilities. 

In light of our decision to approve the “add in” approach for 100 kV-200 kV facilities, 

and after consideration of the comments, we agree with NERC that this is an appropriate 

effective date. 

283. Additionally, in light of our directive to the ERO to expand the Reliability 

Standard’s scope to include sub-100 kV facilities that Regional Entities have already 

identified as necessary to the reliability of the Bulk-Power System through inclusion in 

the Compliance Registry, we direct the ERO to modify the Reliability Standard to include 

an implementation plan for sub-100 kV facilities. 

 192 EEI at 28. 
Docket No. RM08-13-000 - 168 - 

284. We also direct the ERO to remove the exceptions footnote from the “Effective 

Dates” section. As the Commission stated in the NOPR, the exceptions footnote is 

addressed to potential enforcement actions, and is therefore best left out of the Reliability 

Standard and addressed in NERC’s compliance and enforcement program. Moreover, we 

agree with Oncor that the need for the temporary exemption has expired and therefore 

should be removed from the Reliability Standard. We add that entities are free to request 

exceptions through NERC’s existing process, subject to Commission review and 

approval. 

K. Violation Risk Factors

285. Requirement R1 directs entities to set their relays according one of the options set 

forth in sub-requirements R1.1 through R1.13. NERC assigned Requirement R1 a “high” 

violation risk factor, but did not assign violation risk factors to sub-requirements R1.1 

through R1.13. 

286. Requirement R2 provides that entities that set their relays according to subrequirements R1.6 through R1.9, R1.12, or R1.13 must use the calculated circuit 

capability as the circuit’s facility rating and must obtain the agreement of the planning 

coordinator, transmission operator, and reliability coordinator as to the calculated circuit 

capability. NERC assigned Requirement R2 a “medium” violation risk factor. 
Docket No. RM08-13-000 - 169 - 

287. Requirement R3 requires planning coordinators to determine which sub-200 kV 

facilities are critical to the reliability of the bulk electric system and therefore subject to 

Requirement R1.193 NERC assigned Requirement R3 a “medium” violation risk factor. 

1. NOPR Proposal

288. In the NOPR, the Commission listed the five guidelines that it uses to evaluate 

proposed violation risk factor assignments (Violation Risk Factor Guidelines). 

According to these Guidelines, violation risk factor assignments should be consistent: 

(1) with the conclusions of the Final Blackout Report; (2) within a Reliability Standard; 

(3) among Reliability Standards with similar Requirements; and (4) with NERC’s 

definition of the violation risk factor level; the Commission also stated that (5) the 

violation risk factor levels for Requirements that co-mingle a higher risk reliability 

objective and a lower risk reliability objective must not be watered down to reflect the 

lower risk level associated with the less important reliability objective.194 

 193 As proposed by NERC, Requirement R3 directs planning coordinators to 

identify the 100 kV-200 kV facilities that should be subject to Requirement R1. As we 

have explained, in this Final Rule we direct that the ERO revise Requirement R3 so that 

planning coordinators also identify sub-100 kV facilities that should be subject to the 

Reliability Standard. 

194 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 88. For a complete discussion of 

each guideline, see North American Electric Reliability Corp., 119 FERC ¶ 61,145, 

P 19-36 (Violation Risk Factor Order), order on reh’g and compliance filing, 120 FERC 

¶ 61,145 (2007) (Violation Risk Factor Rehearing Order). 
Docket No. RM08-13-000 - 170 - 

289. The Commission agreed with NERC that Requirement R1 should be assigned a 

“high” violation risk factor. The Commission added, however, that violation of any of 

the criteria in sub-requirements R1.1 through R1.13 present the same reliability risk as a 

violation of Requirement R1 because they set forth the options for compliance with 

Requirement R1. Consequently, the Commission proposed to direct the ERO to assign a 

“high” violation risk factor to each sub-requirement. 

290. The Commission also proposed to direct the ERO to modify the violation risk 

factor assigned to Requirement R3 and its sub-requirements to reflect the Commission’s 

applicability proposals. 

2. Comments

291. NERC and other commenters oppose the Commission’s proposal to assign a 

separate violation risk factor to sub-requirements R1.1 through R1.13. These 

commenters argue that the sub-requirements are alternative ways to comply with 

Requirement R1, not separate Requirements that must be complied with in their own 

right. The commenters point out that each sub-requirement is intended to address a 

different operating condition or system design condition and that, for any specific circuit, 

entities will set their relays pursuant to only one of the sub-requirements. NERC adds 

that its proposal to assign violation risk factors only to Requirement R1 is consistent with 
Docket No. RM08-13-000 - 171 - 

its informational filing in Docket No. RM08-11-000, where it described more fully its 

plans for a new, comprehensive approach to assigning violation risk factors.195 

292. An individual commenter, Michael McDonald, argues that Requirement R1 should 

have a “medium” violation risk factor, rather than a “high” violation risk factor, because 

actions taken since the August 2003 blackout have reduced the likelihood that a relay 

loadability issue will cause a cascading outage. 

3. Commission Determination

293. We approve NERC’s assignment of a “high” violation risk factor to Requirement 

R1 and a “medium” violation risk factor to Requirement R2. These violation risk factor 

assignments are consistent with the Violation Risk Factor Guidelines. 

294. We disagree with Michael McDonald, who argues that Requirement R1 should 

have a “medium” violation risk factor rather than a “high” violation risk factor. Violation 

risk factor assignments represent the risk a violation of a Requirement presents to the 

Bulk-Power System.196 Although the Commission, the ERO, and industry have taken 

actions since the August 2003 blackout to reduce the likelihood that relay outages will 

cause cascading outages, these actions do not mitigate the risk of non-compliance with 

Requirement R1. In our view, a violation of Requirement R1 has the potential to put the 

 195 In its informational filing, NERC indicates that NERC drafting teams will 

develop “rolled up” violation risk factors and violation severity levels. 

196 North American Electric Reliability Corp., 121 FERC ¶ 61,179, at P 38 (2007). 
Docket No. RM08-13-000 - 172 - 

 

Bulk-Power System at the risk of cascading outages like those that occurred during the 

August 2003 blackout. Consequently, we agree with the ERO that Requirement R1 

should be assigned a “high” violation risk factor. 

295. We will not require the ERO to assign a violation risk factor to each subrequirement of Requirement R1 because we agree with the ERO that the subrequirements are alternative ways, based on different operating or design configurations, 

of complying with Requirement R1. Consequently, an entity’s failure to appropriately 

apply one of the sub-requirements of Requirement R1 to a specific operating design or 

configuration is, as a violation of Requirement R1, subject to a “high” violation risk 

factor. While the Commission generally expects that the ERO will assign a violation risk 

factor to each Requirement and sub-requirement of a Reliability Standard, we will accept 

the ERO’s proposal not assign violation risk factors to sub-requirements R1.1 through 

R1.13 as an exception to our current policy because we are satisfied that the subrequirements do not constitute independent compliance requirements separate from 

Requirement R1.197

197 NERC’s assignment of violation risk factors in Reliability Standard PRC-023-1 

appears to be consistent with the approach to assigning violation risk factors set forth in 

NERC’s informational filing in Docket No. RM08-11-000. At NERC’s request, the 

Commission has not acted on the informational filing. The Commission understands, 

however, that NERC anticipates formally filing a comprehensive “roll up” plan in the 

second quarter of 2010. Consequently, we direct the ERO to re-file the violation risk 

factors associated with the Requirements of PRC-023-1 when it submits its 

comprehensive plan. 
Docket No. RM08-13-000 - 173 - 

 

296. We also agree with the ERO’s decision to assign Requirement R2 a “medium” 

violation risk factor. Requirement R2 comprises two reliability obligations: (1) the 

required use of the calculated circuit capability as the facility rating of the circuit for 

entities that set their relays according to sub-requirements R1.6 through R1.9, R1.12, or 

R1.13; and (2) the entities’ obligation to obtain the agreement of the planning 

coordinator, transmission operator, and reliability coordinator as to the calculated circuit 

capability. Requirement R2 co-mingles more than one reliability obligation and, 

consistent with Violation Risk Factor Guideline 5, the assigned violation risk factor 

reflects the reliability risk of a violation of the higher reliability obligation (i.e., the 

requirement to use the calculated circuit capability as the facility rating of the circuit). 

297. Finally, we direct the ERO to assign a “high” violation risk factor to Requirement 

R3. The Commission expects consistency between violation risk factors assigned to 

Requirements that address similar reliability goals.198 NERC assigned a “high” violation 

risk factor to Requirement R1, which requires entities to set their relays according to one 

of the criteria in sub-requirements R1.1 through R1.13. Requirement R3 directs planning 

coordinators to determine which sub-200 kV facilities will be subject to Requirement R1. 

Since the facilities identified by the planning coordinator pursuant to Requirement R3 are 

required to meet Requirement R1, we conclude that the reliability risk to the Bulk-Power 

198 Violation Risk Factor Order, 119 FERC ¶ 61,145 at P 25. 
Docket No. RM08-13-000 - 174 - 

System of a violation of Requirement R3 is the same as a violation of Requirement R1. 

We direct the ERO to file the new violation risk factor no later than 30 days after the 

date of this Final Rule. 

L. Violation Severity Levels

298. NERC proposed violation severity levels for Requirements R1, R2, and R3, but 

not for sub-requirements R1.1 through R1.13 or R3.1 through R3.3. 

299. For Requirement R1, NERC proposed: (1) a “moderate” violation severity level 

when an entity complies with a sub-requirement of Requirement R1, but has incomplete 

or incorrect evidence of compliance; and (2) a “severe” violation severity level when an 

entity fails to comply with a sub-requirement of Requirement R1, or when the entity 

lacks any evidence of compliance. 

300. NERC designated Requirement R2 as a “binary” Requirement and proposed a 

“lower” violation severity level when an entity sets its relays pursuant to subrequirements R1.6 through R1.9, R1.12, or R1.13, but lacks evidence that it obtained the 

agreement of the planning coordinator, transmission operator, and reliability coordinator 

as to the calculated circuit capability.199 

301. For Requirement R3, NERC proposed: (1) a “severe” violation severity level 

when an entity lacks a process to identify critical facilities; and (2) “moderate” and 

 199 “Binary” Requirements are Requirements where compliance is defined in terms 

of “pass” or “fail.” 
Docket No. RM08-13-000 - 175 - 

“high” violation severity levels based on the number of days that a planning coordinator 

is late in providing the critical facilities list to the entities that must receive it. 

1. NOPR Proposal

302. In the NOPR, the Commission listed the four guidelines that it uses to evaluate 

proposed violation severity levels (Violation Severity Level Guidelines).200 According to 

these Guidelines, violation severity levels should: (1) avoid the unintended consequence 

of lowering the current level of compliance; (2) ensure uniformity and consistency among 

all approved Reliability Standards in the determination of penalties; 201 (3) be consistent 

 200 For a complete discussion of each guideline, see North American Electric 

Reliability Corporation, 123 FERC ¶ 61,284, at P 19-36 (Violation Severity Level 

Order), order on reh’g and compliance filing, 125 FERC ¶ 61,212 (2008) (Violation 

Severity Level Rehearing Order). 

201 In the Violation Severity Level Order, the Commission identified two specific 

concerns with the uniformity and consistency of the violation severity level assignments 

then under review: (a) the single violation severity levels assigned to individual binary 

requirements were not consistent; and (b) the violation severity level assignments 

contained ambiguous language. With respect to concern identified in (a), which the 

Commission referred to as “Guideline 2a,” the Commission explained that NERC 

assigned different violation severity levels to different binary Requirements (i.e. pass/fail 

Requirements) without justifying the different assignments or explaining how they were 

consistent with the application of a basic pass/fail test. The Commission directed NERC 

to modify the violation severity levels by either: (1) consistently applying the same 

severity level to each binary Requirement; or (2) changing from a binary approach to a 

gradated approach. Violation Severity Level Order 123 FERC ¶ 61,284 at P 23-27, 

45-47. In its compliance filing, NERC chose the first option and proposed to apply a 

“severe” violation severity level to each of the binary Requirements. The Commission 

agreed with this approach. North American Electric Reliability Corporation, 127 FERC 

¶ 61,293, at P 5, 11 (2009). 
Docket No. RM08-13-000 - 176 - 

with the corresponding Requirement; and (4) be based on a single violation, not on a 

cumulative number of violations. 

303. The Commission observed that the violation severity levels assigned to 

Requirements R1 and R2 appear to be inconsistent with Violation Severity Level 

Guideline 3. The Commission noted that the two violation severity levels proposed for 

Requirement R1 address both: (1) the severity of a violation (i.e., the fact that relay 

settings do not comply with Requirement R1); and (2) facts necessarily associated with 

evaluating compliance (i.e., the existence of evidence that relay settings comply with 

Requirement R1). The Commission explained that Requirement R1 does not require 

evidence of compliance, only compliance. Similarly, the Commission stated that the 

single violation severity level proposed for Requirement R2 does not reflect the severity 

of a violation of Requirement R2, but the severity of lacking evidence of compliance with 

Requirement R2. Consequently, the Commission proposed to direct the ERO to: 

(1) adopt a binary approach to Requirement R1; i.e., assign a violation severity level 

based on whether or not the entity complies with Requirement R1; and (2) assign a 

violation severity level for Requirement R2 that addresses an entity’s failure to comply 

with the entire Requirement; i.e., its failure to calculate circuit capability as the facility 

rating and obtain agreement on that rating with the required entities. The Commission 

also proposed to direct the ERO to assign a single violation severity level to each subrequirement in Requirement R1. 
Docket No. RM08-13-000 - 177 - 

304. The Commission also stated that the single violation severity level assigned to 

Requirement R2 appears to be inconsistent with NERC’s Guideline 2a compliance filing 

in Docket No. RR08-4-004.202 The Commission explained that, in that docket, NERC 

assigned “severe” violation severity levels to binary Requirements. The Commission 

added that it expects the violation severity levels assigned to binary requirements to be 

consistent, and proposed to direct the ERO to revise the violation severity level assigned 

to Requirement R2 to be consistent with Guideline 2a. 

305. Finally, in light of its proposals to direct the ERO to modify Requirement R3 and 

its sub-requirements, the Commission proposed to direct the ERO to assign new violation 

severity levels to Requirement R3 and its sub-requirements, consistent with the Violation 

Severity Level Guidelines. 

2. Comments

306. NERC agrees with the Commission’s proposal to review the violation severity 

levels in accordance with the Violation Severity Level Guidelines.203 Other commenters 

oppose the Commission’s proposal to assign a violation severity level to each subrequirement in Requirement R1 for the same reasons that they oppose assigning a 

violation risk factor to each sub-requirement in Requirement R1. 

 202 See supra n. 202. 

203 NERC Comments at 40. 
Docket No. RM08-13-000 - 178 - 

307. Consumers Energy makes the general argument that “evidence” should be 

included in Requirements only when the compliance monitor (e.g., the Regional Entity or 

NERC) uses it for a reliability purpose. Consumers Energy argues that if evidence is 

used only to determine whether an entity is in compliance with a Reliability Standard, the 

evidence should be instead represented in a Measure as reflected in PRC-023-1. 

3. Commission Determination

308. We adopt the NOPR proposals with respect to the violation severity levels 

assigned to Requirements R1 and R2. As we explained in the NOPR, the violation 

severity levels assigned to Requirement R1 are inconsistent with Violation Severity 

Guideline 3 because they are based in part on the amount of evidence of compliance that 

an entity can produce, even though Requirement R1 does not require entities to have 

evidence of compliance. Consequently, we direct the ERO to assign a single violation 

severity level of “severe” for violations of Requirement R1. 

309. While we adopt the NOPR proposal with respect to Requirement R1, we do not 

adopt the NOPR proposal to direct the ERO to assign individual violation severity levels 

to the sub-requirements of Requirement R1. As we explained with respect to the 

violation risk factors, we will make an exception to our general policy because we are 
Docket No. RM08-13-000 - 179 - 

satisfied that the sub-requirements of Requirement R1 do not constitute independent 

compliance requirements separate from Requirement R1.204

310. We also adopt the NOPR proposal with respect to the violation severity level 

assigned to Requirement R2. As the Commission pointed out in the NOPR, the single 

violation severity level assigned to Requirement R2 suffers from the same problem as the 

two violation severity levels assigned to Requirement R1; namely, it is based in part on 

whether an entity has evidence of compliance with the Requirement, even though the 

Requirement itself does not require an entity to have evidence of compliance. 

Additionally, Requirement R2 is a binary Requirement, and NERC’s assignment of a 

“lower” violation severity level rather than a “severe” violation severity level is 

inconsistent with its Guideline 2a compliance filing in Docket No. RR08-4-004. In that 

filing, NERC assigned a “severe” violation severity level to binary Requirements. As the 

Commission stated when discussing Guideline 2a in the Violation Severity Level Order, 

single violation severity levels assigned to binary requirements should be consistent. 

Accordingly, we direct the ERO to change the violation severity level assigned to 

Requirement R2 from “lower” to “severe” to be consistent with Guideline 2a. 

 204 Consistent with our treatment of violation risk factors, we direct the ERO to refile the violation severity factors associated with the Requirements of PRC-023-1 when it 

submits its comprehensive plan. 
Docket No. RM08-13-000 - 180 - 

311. Finally, we direct the ERO to assign a “severe” violation severity level to 

Requirement R3. Requirement R3 directs planning coordinators to identify the critical 

sub-200 kV facilities that are subject to the Reliability Standard. Similar to our 

determination for Requirement R2, it is our view that Requirement R3 is a binary 

requirement; either the planning coordinator identified critical facilities or it did not. 

Consequently, we find that Requirement R3 must have a single violation severity level of 

“severe.” 

312. We direct the ERO to file the new violation severity levels described in our 

discussion no later than 30 days after the date of this Final Rule. 

M. Miscellaneous

 1. Purpose of the Reliability Standard

313. The Reliability Standard’s stated purpose is to “require[] certain transmission 

owners, generator owners, and distribution providers to set protective relays according to 

specific criteria in order to ensure that the relays reliably detect and protect the electric 

network from all fault conditions, but do not limit transmission loadability or interfere 

with system operators’ ability to protect system reliability.” 

a. Comments

314. BPA argues that the Commission should direct the ERO to revise the Reliability 

Standard’s stated purpose because the Standard requires only that certain protective 

relays refrain from operating during permissible load conditions and does not require that 
Docket No. RM08-13-000 - 181 - 

protective relays reliably detect and protect the electric network from all fault conditions. 

BPA asserts that sub-requirement R1.12 touches on the subject of adequately detecting 

faults by allowing the loadability requirements of relay settings to be relaxed in order to 

allow adequate protection, but adds that neither sub-requirement R1.12 nor any other subrequirement requires relays to be set to reliably detect “all” fault conditions and protect 

the electrical network from these faults. BPA argues that the class of relays covered by 

the Reliability Standard is not even capable of detecting “all” fault conditions. BPA 

requests, therefore, that the Commission direct the ERO to revise the Reliability 

Standard’s stated purpose to be: “[t]o prevent certain protective relays from operating 

under permissible transmission line and equipment loads.”205

b. Commission Determination

315. We disagree with BPA. Requirement R1 directs entities to set their relays 

according to one of its sub-requirements (R1.1 through R1.13), based on their 

transmission configurations. No matter what setting entities choose, they are required to 

apply it while “maintaining reliable protection of the bulk electric system for all fault 

conditions.” Thus, any sub-requirement that an entity implements must protect the 

electric network from all fault conditions. 

 205 BPA at 1-2. 
Docket No. RM08-13-000 - 182 - 

2. Transmission Facility Design Margin

 a. Comments

316. Basin interprets the Commission’s statement in the NOPR that “[s]ubrequirement R1.1 specifies transmission line relay settings based on the highest seasonal 

facility rating using the 4-hour thermal rating of a line, plus a design margin of 150 

percent” to suggest that the Commission incorrectly assumed that relay margins include 

an additional transmission facility design margin, and that additional Total Transfer 

Capability (TTC) can be achieved with different relay settings. Basin states that relay 

operations do not affect the calculation of TTC because relay settings are established 

above the level of standard operation of the system and will not operate when facilities 

are loaded at their maximum ratings. 

b. Commission Determination

317. We clarify that the Commission did not assume that “design margin,” as it is 

used in the context of the Reliability Standard, equates to additional TTC on the 

transmission facility. The statement in the NOPR that Basin refers to is a direct quote 

from NERC where NERC describes “design margin” in the context of the margin 

(percentage) over the 4-hour facility rating protective relay setting criteria for sub-
Docket No. RM08-13-000 - 183 - 

requirement R1.1.206 The “design margin” described in this requirement is different than 

the “transmission reliability margin” that accounts for the inherent uncertainty in bulk 

electric system conditions in the calculation of TTC established in the Modeling, Data, 

and Analysis (MOD) Reliability Standards. 

IV. Information Collection Statement

318. The Office of Management and Budget (OMB) regulations require that OMB 

approve certain reporting and recordkeeping (collections of information) imposed by an 

agency.207 The information collection requirements in this Final Rule are identified 

under the Commission data collection, FERC-725G “Transmission Relay Loada

Mandatory Reliability Standard for the Bulk Power System.” Under section 3507(d) of 

the Paperwork Reduction Act of 1995,

bility 

 

208 the proposed reporting requirements in the 

subject rulemaking will be submitted to OMB for review. Interested persons may obtain 

information on the reporting requirements by contacting the Federal Energy Regulatory 

Commission, 888 First Street, NE, Washington, DC 20426 (Attention: Michael Miller, 

Office of the Executive Director, 202-502-8415) or from the Office of Management and 

206 NERC Petition at 9. 

207 5 CFR 1320.11. 

208 44 U.S.C. 3507(d). 
Docket No. RM08-13-000 - 184 - 

Budget (Attention: Desk Officer for the Federal Energy Regulatory Commission, 

fax: 202-395-7285, e-mail: oira_submission@omb.eop.gov). 

319. The “public protection” provisions of the Paperwork Reduction Act of 1995 

requires each agency to display a currently valid control number and inform respondents 

that a response is not required unless the information collection displays a valid OMB 

control number on each information collection or provides a justification as to why the 

information collection number cannot be displayed. In the case of information 

collections published in regulations, the control number is to be published in the Federal

Register. 

320. Public Reporting Burden: In the NOPR, the Commission based its estimate of 

the Public Reporting Burden on the NERC Compliance Registry, as of March 3, 2009, 

and on NERC’s July 30, 2008 petition for approval of PRC-023-1. The Commission 

stated that, as of March 3, 2009, NERC had registered in its Compliance Registry: 

(1) 568 distribution providers; (2) 825 generator owners; (3) 324 transmission owners; 

and (4) 79 planning authorities. The Commission also noted that the Reliability Standard 

does not apply to all transmission owners, generator owners, and distribution providers, 

but only to those with load-responsive phase protection systems as described in 

Attachment A of the Standard, applied to all transmission lines and transformers with 

low-voltage terminals operated or connected at 200 kV and above and between 100 kV 

and 200 kV as identified by the planning coordinator as critical to the reliability of the 
Docket No. RM08-13-000 - 185 - 

bulk electric system. The Commission further noted that some entities are registered for 

multiple functions, so there is some overlap between the entities registered as distribution 

providers, transmission owners, and generator owners. Given these parameters, the 

Commission estimated the Public Reporting Burden as follows: 

Data Collection No. of 

Respondents 

No. of 

Responses 

Hours Per 

Respondent 

Total Annual 

Hours 

FERC-725G

Reporting: 

0 

Reporting: 

0 

M1 - TOs, GOs 

and DPs must 

“have evidence” 

to show that 

each of its 

transmission 

relays are set 

according to 

Requirement R1 

450 1 

Recordkeeping: 

100 

Recordkeeping:

 45,000 

M2 – Certain Reporting: 0 Reporting: 0 

TOs, GOs and 

DPs must have 

evidence that a 

166 1 

Recordkeeping: 

10 

Recordkeeping: 

1,660 
Docket No. RM08-13-000 - 186 - 

facility rating 

was agreed to by 

PA, TOP and 

RC 

M3 - PC must 

document 

process for 

determining 

critical facilities 

and (2) a current 

list of such 

facilities 

79 1 175 13,825 

Total 60,485 

Based on the available information from the compliance registry, the Commission 

estimated that 525 entities would be responsible for compliance with the Reliability 

Standard.209 The Commission also estimated that it would require 60,485 total annual 

hours for collection (reporting and recordkeeping) and that the average annualized cost of 

 209 NOPR, FERC Stats. & Regs. ¶ 32,642 at P 117 
Docket No. RM08-13-000 - 187 - 

 

compliance would be $2,419,400 ($40/hour for 60,485 hours; the Commission based the 

$40/hour estimate on $17/hour for a file/record clerk and $23/hour for a supervisor).210

321. Several commenters express concern with the burden to be imposed by the 

Reliability Standard. Some of these comments address the Reliability Standard’s 

potential impact on small entities; because these comments are also the subject of the 

analysis performed under the Regulatory Flexibility Act, the Commission has provided a 

response under that section of this rulemaking. Other comments question the 

Commission’s initial burden estimate. 

322. APPA argues that the Commission has grossly underestimated the Public 

Reporting Burden and requests that the Commission develop a more accurate estimate. 

APPA notes that the Commission provided a breakdown by category of registered entities 

for a total of 1,717 entities, but then asserts that only 525 entities will be subject to 

PRC-023-1 as proposed by NERC. APPA states that it cannot assess how the 

Commission came up with this lower number, as the Commission provided no 

explanation of its methodology or the data it used to reach this conclusion. APPA states 

that the Commission’s initial estimate appears to be based on the Reliability Standard as 

proposed by NERC, and therefore fails to account for the Commission’s proposals to 

210 BPA notes that the NOPR erroneously showed this figure as $241,940 rather 

than $2,419,400. 
Docket No. RM08-13-000 - 188 - 

expand the Standard’s applicability. APPA argues that the Commission must assess the 

Public Reporting Burden created by its proposals. 

323. APPA also claims that the Commission’s estimate of labor costs is so low as to 

be completely erroneous for burden evaluation purposes. Based on an informal survey of 

its members that own or operate transmission facilities above 100 kV, APPA states that 

21 out of nearly 300 registered public power utilities would need to evaluate 791 

terminals to comply with the Commission‘s proposals. At an estimated cost of between 

$500 and $1,200 per location, APPA estimates that the cost of compliance for these 21 

members would be between $395,500 and $949,200; the Commission estimated 

$2,419,400 for the entire industry. APPA adds that entities will need seasoned and 

expensive electrical engineers and outside consultants to comply with the Commission’s 

proposals, not file/record clerks who are paid $17 per hour or supervisory personnel who 

are paid $23 per hour. APPA reports that one of its members estimates that it would have 

to use engineers, managers and even director-level personnel to carry out the required 

tasks, at an estimated cost of $55–$75 per hour. APPA expects that the cost of external 

consultants could reach $200 per hour. 

324. BPA states that the loaded cost for an engineer is approximately $80 per hour, 

twice the $40 per hour the Commission estimated for a file clerk and a supervisor. BPA 

observes that this would double the estimated annual cost of the Reliability Standard to 

$4,838,800. BPA also questions the estimate of 100 hours annually for each respondent 
Docket No. RM08-13-000 - 189 - 

to comply with Requirement R1. BPA states that it could take thousands of hours for 

larger utilities. 

325. EEI argues that the Commission’s estimate of hours for reporting and 

recordkeeping substantially underestimates the actual cost, in both time and money, 

required to comply with the Commission’s modifications. EEI reports that one smaller 

investor-owned utility has estimated that it would take 4-8 hours of engineering time, per 

relay terminal, to review the more than 850 line terminals on its system operated between 

100 kV and 200 kV. EEI states that it would take an additional 6-12 hours of engineering 

time per terminal if, as the utility expects, about one third of its line terminals require 

mitigation, and another 6-12 hours of operations and maintenance staff hours to 

implement relay settings for terminals requiring mitigation. 

326. EEI asserts that it could cost $40,000 to replace each terminal in order to comply 

with the Commission’s modifications. EEI states that there are more than 100,000 line 

terminals in the U.S. on facilities between 100 kV and 200 kV that would have to be 

checked if the Commission adopts a “rule out” approach. EEI estimates that this review 

could take 1.5 million labor hours, and another 750,000 hours if just one-half of the 

terminals must be replaced. EEI states that the aggregate cost to replace these terminals 

could exceed $2.4 billion. 

327. Given the Commission’s decision not to adopt the “rule out” approach, most of 

these comments are no longer relevant. However, in response to the comments that 
Docket No. RM08-13-000 - 190 - 

remain relevant, and upon further review, we have revised our initial estimates as 

reflected below. 

Information Collection Costs: The Commission sought comments about the 

information collection costs needed to comply with PRC-023-1. Since many of the 

comments the Commission received estimated costs based on the “rule out” approach, 

they are no longer applicable given our decision in this Final Rule not to require the “rule 

out” approach. However, some commenters argue, apart from the “rule out” approach, 

that the NOPR underestimated the hours required to comply and the estimated cost of 

labor. After further consideration, with respect to the costs of labor, we agree that the 

$40/hour estimate for file/record clerks and supervisory employees is not correct. We 

also agree with commenters that electrical engineers will be required to comply with 

PRC-023-1. Therefore, we have revised estimates as indicated below: 

 Number of line terminals to be reviewed: 53,000 

 Number of hours per terminal: 6.4 

 Hourly rate for review by engineers: $120 

Total Cost for review = (terminals to be reviewed x hours per terminal) x hourly rate for 

review by engineers = (53,000 x 6.4) x ($120/hour) = 339,200 hours x 120/hour = 

$40,704,000 

Sources: 

 Title: FERC-725-G “Mandatory Reliability Standard for Transmission Relay 

Loadability.” 
Docket No. RM08-13-000 - 191 - 

 Action: Proposed Collection of Information. 

 OMB Control No: [To be determined.] 

 Respondents: Business or other for profit, and/or not for profit institutions. 

 Frequency of Responses: On Occasion. 

 Necessity of the Information: The Transmission Relay Loadability Reliability 

Standard, if adopted, would implement the Congressional mandate of the Energy Policy 

Act of 2005 to develop mandatory and enforceable Reliability Standards to better ensure 

the reliability of the nation’s Bulk-Power System. Specifically, the proposed Reliability 

Standard would ensure that protective relays are set according to specific criteria to 

ensure that relays reliably detect and protect the electric network from all fault 

conditions, but do not limit transmission loadability or interfere with system operator’s 

ability to protect system reliability. 

328. Interested persons may obtain information on the reporting requirements by 

contacting: Federal Energy Regulatory Commission, 888 First Street, NE, Washington, 

DC 20426 [Attention: Michael Miller, Office of the Executive Director, Phone: (202) 

502-8415, fax: (202) 273-0873, e-mail: michael.miller@ferc.gov]. Comments on the 

requirements of the proposed rule may also be sent to the Office of Information and 

Regulatory Affairs, Office of Management and Budget, Washington, DC 20503 

[Attention: Desk Officer for the Federal Energy Regulatory Commission], e-mail: 

oira_submission@omb.eop.gov. 
Docket No. RM08-13-000 - 192 - 

V. Environmental Analysis 

329. The Commission is required to prepare an Environmental Assessment or an 

Environmental Impact Statement for any action that may have a significant adverse effect 

on the human environment.211 The Commission has categorically excluded certain 

actions from this requirement as not having a significant effect on the human 

environment. The actions proposed here fall within the categorical exclusion in the 

Commission’s regulations for rules that are clarifying, corrective or procedural, for 

information gathering, analysis, and dissemination.212 Accordingly, neither an 

environmental impact statement nor environmental assessment is required. 

 211 Order No. 486, Regulations Implementing the National Environmental Policy 

Act, 52 FR 47,897 (Dec. 17, 1987), FERC Stats. & Regs. ¶ 30,783 (1987). 

212 18 CFR 380.4(a)(5) (2009). 
Docket No. RM08-13-000 - 193 - 

VI. Regulatory Flexibility Act

330. The Regulatory Flexibility Act of 1980 (RFA)213 generally requires a description 

and analysis of any final rule that will have significant economic impact on a substantial 

number of small entities. The RFA does not mandate any particular outcome in a 

rulemaking, but rather requires consideration of alternatives that are less burdensome to 

small entities and an agency explanation of why alternatives were rejected. 

331. In drafting a rule, an agency is required to: (1) assess the effect that its regulation 

will have on small entities; (2) analyze effective alternatives that may minimize a 

regulation’s impact; and (3) make the analyses available for public comment.214 In its 

NOPR, the agency must either include an Initial Regulatory Flexibility Act Analysis 

(Initial Analysis)215 or certify that the proposed rule will not have a “significant impact 

on a substantial number of small entities.”216

 

332. If, in preparing the NOPR, an agency determines that the proposal could have a 

significant impact on a substantial number of small entities, the agency shall ensure that 

small entities will have an opportunity to participate in the rulemaking procedure.217

213 5 U.S.C. 601-612. 

214 5 U.S.C. 601-604. 

215 5 U.S.C. 603(a). 

216 5 U.S.C. 605(b). 

217 5 U.S.C. 609(a). 
Docket No. RM08-13-000 - 194 - 

 

333. In its Final Rule, the agency must also either prepare a Final Regulatory 

Flexibility Act Analysis (Final Analysis) or make the requisite certification. Based on the 

comments the agency receives on the NOPR, it can alter its original position as expressed 

in the NOPR but it is not required to make any substantive changes to the proposed 

regulation. 

334. The statute provides for judicial review of an agency’s final RFA certification or 

Final Analysis.218 An agency must file a Final Analysis demonstrating a “reasonable, 

good-faith effort” to carry out the RFA mandate.219 However, the RFA is a procedural, 

not a substantive, mandate. An agency is only required to demonstrate a reasonable, good 

faith effort to review the impact the proposed rule would place on small entities, any 

alternatives that would address the agency’s and small entities’ concerns and their 

impact, provide small entities the opportunity to comment on the proposals, and review 

and address comments. An agency is not required to adopt the least burdensome rule. 

Further, the RFA does not require an agency to assess the impact of a rule on all small 

entities that may be affected by the rule, only on those entities that the agency directly 

regulates and that are subject to the requirements of the rule.220

218 5 U.S.C. 611. 

219 United Cellular Corp. v. FCC, 254 F.3d 78, 88 (D.C. Cir. 2001); Alenco 

Commc’ns, Inc. v. FCC, 201 F.3d 608, 625 (5th Cir. 2000). 

220 Mid-Tex Elec. Coop., Inc. v. FERC, 773 F.2d 327 (D.C. Cir. 1985). 
Docket No. RM08-13-000 - 195 - 

A. NOPR Proposal 

335. In the NOPR, the Commission asserted that most of the entities, i.e., transmission 

owners, generator owners, distribution providers, and “planning coordinators,” or 

alternatively “planning authorities,” to which the requirements of this rule will apply, do 

not fall within the applicable definition of “small entities.” The Commission also stated 

that, based on available information regarding NERC’s compliance registry, 

approximately 525 entities will be responsible for compliance with the new Reliability 

Standard. Consequently, the Commission certified that the Reliability Standard will not 

have a significant adverse impact on a substantial number of small entities and that no 

RFA analysis was required. 

B. Comments

336. APPA, TAPS, NRECA, and SWTDUG argue that the “rule out” approach for 

100 kV-200 kV facilities and the “add in” approach for sub-100 kV facilities will cause 

the Reliability Standard to have a significant adverse impact on a substantial number of 

small entities. 

337. NRECA argues that the Commission’s Initial Analysis is inadequate and its 

conclusion premature given the Commission’s proposals to expand the Reliability 

Standard’s applicability. NRECA argues that the Commission cannot develop an 

adequate Final Analysis without an Initial Analysis that lays the proper foundation for 

eliciting comments and seeking information. APPA argues that the Commission’s Initial 
Docket No. RM08-13-000 - 196 - 

Analysis is flawed and fails to: (1) assess the effect the regulation will have on small 

entities; (2) analyze effective alternatives that might minimize the regulation’s impact; 

and (3) make such an analysis available for public comment. 

338. APPA and NRECA also argue that the Commission failed to: (1) provide its 

basis for claiming that only 525 entities from the NERC Compliance Registry will be 

required to comply with the Reliability Standard; (2) justify its assertion that the majority 

of the expected 525 entities required to comply do not qualify as small entities under the 

Small Business Act; (3) state how many of the 525 affected entities are small entities; and 

(4) identify the registered entities that are required to comply. APPA argues that the 

Commission’s expectation that 525 facilities will be required to comply with the 

Reliability Standard is based on the Reliability Standard as proposed by NERC, and does 

not account for the Commission’s potentially broader applicability proposals. APPA 

states that 261 of its members are registered entities and qualify as small entities. 

NRECA adds that a substantial majority of its approximately 930 rural electric 

cooperative members are small entities that would be adversely impacted by the proposed 

rule. 

339. TAPS argues that the “rule out” approach will increase the burden on small 

systems and may force the Commission to depart from the Compliance Registry criteria 

that formed the basis for its RFA certification in Order No. 693. TAPS explains that if 

the “rule out” approach will make all 100 kV facilities subject to the Reliability Standard, 
Docket No. RM08-13-000 - 197 - 

including radial transmission lines, then the Standard will apply to unregistered small 

entities that have not previously been considered part of the bulk electric system and 

therefore do not appear on the Compliance Registry that served as the basis for the 

Commission’s small entity impacts analysis. 

C. Commission Determination

340. As discussed previously in this Final Rule, the Commission will not adopt the 

NOPR proposal to make PRC-023 applicable to all facilities operated at or above 100 kV, 

“ruling out” those facilities that would not demonstrably result in cascading outages, 

instability, uncontrolled separation, violation of facility ratings, or interruption of firm 

transmission service. Accordingly, to the extent that the Commission has decided to 

abandon the “rule out” approach in favor of an “add-in” approach, as discussed in 

previous portions of this Final Rule, the Commission expects that many of the concerns 

and impact estimates submitted by commenters are moot or no longer accurate. 

341. Nonetheless, the Commission does find it appropriate to address commenters’ 

concern regarding the number of entities that the Commission estimates will be subject to 

PRC-023-1 as proposed by NERC. Based on the Compliance Registry dated November 

30, 2009, there are 573 entities registered as Distribution Providers, 821 entities 

registered as Generator Owners, 323 entities registered as Transmission Owners, and 80 

entities registered as Planning Authorities. However, the Commission notes that some 

entities are registered for multiple functions, and therefore recognizes that there is some 
Docket No. RM08-13-000 - 198 - 

 

overlap between the entities registered as a Distribution Provider, Transmission Owner, 

Generator Owner, and/or Planning Authority. Therefore, after eliminating any 

duplicative registrations, the Commission finds that there are 1301 entities that are 

registered as engaging in one or more of the applicable functions within the scope of 

PRC-023-1. 

342. Reliability Standard PRC-023-1 applies to Transmission Owners, Generator 

Owners, and Distribution Providers with load-responsive phase protection systems as 

described in Attachment A of the Reliability Standard, applied to facilities defined in 

requirements 4.1.1 through 4.1.4.221 The Reliability Standard applies to facilities 100 kV 

and above and to transformers with low-voltage terminals 200 kV and above. Because 

there are no commercial generators with a terminal voltage as high as 100 kV and all 

generator step-up and auxiliary power transformers have low-voltage windings well 

below 200 kV, PRC-023-1 excludes generators and all generator step-up and auxiliary 

transformers. Therefore, no generator owner that is not also a transmission owner and/or 

a distribution provider will be subject to PRC-023-1. Accordingly, the Commission 

calculates that the potential applicability of the Final Rule may be reduced by 623, which 

is the total number of entities registered solely as a generator owner. Thus, the 

221 As proposed, the Commission notes PRC-023-1 is applicable to Generator 

Owners with load-responsive phase protection systems as described in Attachment A, 

applied to facilities defined in 4.1.1 through 4.1.4., however, excludes generator 

protection relays that are susceptible to load in Section (3) of Attachment A. 
Docket No. RM08-13-000 - 199 - 

 

Commission anticipates that the Final Rule will apply to approximately 678 entities 

overall.222

343. According to the Department of Energy’s Energy Information Administration 

(EIA), there were 3271 electric utility companies in the United States in 2007,223 and 

approximately 3012 of these electric utilities qualify as small entities under the Small 

Business Act (SBA) definition.224 Of those 3012 small entities, only 80 entities also 

appear in the NERC Compliance Registry. Accordingly, the Commission estimates that 

the Reliability Standard will affect a maximum of 80 SBUs, or approximately 12 percent 

of those entities estimated to be subject to the requirements of the Final Rule. 

344. Based upon on this revised analysis, we certify that this Final Rule will not have 

a significant economic impact on a substantial number of small entities. Accordingly, no 

further RFA analysis is required. 

222 The Commission derives this result by using the following equation: 1301 

applicable entities (entities registered as one of more of the following functions: 

Distribution Provider, Transmission Owner, Generator Owner, and Planning Authority) – 

623 entities registered solely as a Generator Owner = 678. 

223 See U.S. Energy Information Administration, Form EIA-861, Dept. of Energy 

(2007), available at http://www.eia.doe.gov/cneaf/electricity/page/eia861.html. 

224 According to the SBA, a small electric utility is defined as one that has a total 

electric output of less than four million MWh in the preceeding year. 
Docket No. RM08-13-000 - 200 - 

VII. Document Availability

345. In addition to publishing the full text of this document in the Federal Register, 

the Commission provides all interested persons an opportunity to view and/or print the 

contents of this document via the Internet through FERC's Home Page 

(http://www.ferc.gov) and in FERC's Public Reference Room during normal business 

hours (8:30 a.m. to 5:00 p.m. Eastern time) at 888 First Street, NE, Room 2A, 

Washington DC 20426. 

346. From FERC's Home Page on the Internet, this information is available on 

eLibrary. The full text of this document is available on eLibrary in PDF and Microsoft 

Word format for viewing, printing, and/or downloading. To access this document in 

eLibrary, type the docket number excluding the last three digits of this document in the 

docket number field. 

347. User assistance is available for eLibrary and the FERC’s website during normal 

business hours from FERC Online Support at 202-502-6652 (toll free at 1-866-208-3676) 

or email at ferconlinesupport@ferc.gov, or the Public Reference Room at (202) 502-

8371, TTY (202)502-8659. E-mail the Public Reference Room at 

public.referenceroom@ferc.gov. 

VIII. Effective Date and Congressional Notification

348. These regulations are effective [Insert_Date that is 45 days from publication in 

Federal Register for non-major rules and 60 days from the later of the date Congress 
Docket No. RM08-13-000 - 201 - 

receives the agency notice or the date the rule is published in the Federal Register]. The 

Commission has determined, with the concurrence of the Administrator of the Office of 

Information and Regulatory Affairs of OMB, that this rule is not a “major rule” as 

defined in section 351 of the Small Business Regulatory Enforcement Fairness Act of 

1996. 

List of subjects in 18 CFR Part 40 

By the Commission. 

( S E A L ) 

Kimberly D. Bose, 

Secretary. 

 
Docket No. RM08-13-000 - 202 - 

Appendix A – Commenters 

Abbreviation Commenter 

Alcoa Alcoa, Inc. 

Ameren Ameren Services Company 

APPA American Public Power Association 

ATC American Transmission Company, LLC 

Austin Energy City of Austin, Texas 

Basin Basin Electric Cooperative 

BPA Bonneville Power Administration 

California 

Commission 

Public Utilities Commission of the State of California 

City Utilities of 

Springfield 

City Utilities of Springfield, Missouri 

Consumers Energy Consumers Energy Company 

CRC Colorado River Commission of Nevada 

Dominion Dominion Resources, Inc. 

Duke Duke Energy Corporation 

EEI Edison Electric Institute 

ElectriCities ElectriCities of North Carolina, Inc. 
Docket No. RM08-13-000 - 203 - 

Entergy Entergy Services, Inc. 

E.ON E.ON U.S. LLC 

EPSA Electric Power Supply Association 

ERCOT Electric Reliability Council of Texas, Inc. 

Exelon Exelon Corporation 

Fayetteville Public 

Works Commission 

Fayetteville Public Works Commission 

Filing Cooperatives Mohave Electric Cooperative, Inc., Trico Electric Cooperative, 

inc., Navopache Electric Cooperative, Inc., and Sulphur Springs 

Valley Electric Cooperative, Inc. 

Georgia 

Transmission 

Georgia Transmission Corporation 

IESO/Hydro One Independent Electricity System Operator and Hydro One Networks 

Inc. 

IRC The ISO/RTO Council 

ISO New England ISO New England Inc. 

ITC International Transmission Company 

Joint Commenters Independent Electricity System Operator, PJM Interconnection 

L.L.C., Southwest Power Pool, and Midwest Independent 

Transmission Operator 

LES Lincoln Electric System 

Manitoba Hydro Manitoba Hydro 

McDonald Michael McDonald 
Docket No. RM08-13-000 - 204 - 

MDEA Cities Mississippi Delta Energy Agency, Clarksdale Public Utilities 

Commission of the City of Clarksdale, Mississippi, and the Public 

Service Commission of Yazoo City of the City of Yazoo City, 

Mississippi 

MEAG Municipal Electric Authority of Georgia 

NARUC National Association of Regulatory Utility Commissioners 

NERC North American Electric Reliability Corporation 

New York 

Commission 

New York State Public Service Commission 

NRECA National Rural Electric Cooperative Association 

NV Energy NV Energy 

NWCP Northern Wasco County People’s Utility District 

Oncor Oncor Electric Delivery Company LLC 

Ontario Generation Ontario Power Generation Inc. 

PacifiCorp PacifiCorp 

Pacific Northwest 

State Commissions 

Washington Utilities and Transportation Commission, Idaho Public 

Utilities Commission, Public Utility Commission of Oregon, and 

Montana Public Service Commission 

Palo Alto City of Palo Alto, California 

PG&E Pacific Gas & Electric Company 

Portland General Portland General Electric Company 

PSEG Companies Public Service Electric & Gas Company, PSEG Energy Resources 

& Trade LLC, PSEG Power LLC 
Docket No. RM08-13-000 - 205 - 

Public Power 

Council 

Public Power Council 

Seattle City Light Seattle City Light 

Six California 

Cities 

Cities of Anaheim, Azusa, Banning, Colton, Pasadena, and 

Riverside, California 

SoCalEd Southern California Edison Company 

South Carolina 

E&G 

South Carolina Electric & Gas Company 

Southern Southern Company Services, Inc. 

SRP Salt River Project Agricultural Improvement and Power District 

SWTDUG Southwest Transmission Dependent Utility Group 

TANC Transmission Agency of Northern California 

TAPS Transmission Access Policy Study Group 

Tri-State Tri-State Generation & Transmission Association 

TVA Tennessee Valley Authority 

WAPA-RMR Western Area Power Administration-Rocky Mountain Region 

WECC Western Electricity Coordinating Council Relay Work Group 

Y-WEA Y-W Electric Association, Inc.