156 FERC ¶ 61,215

UNITED STATES OF AMERICA

FEDERAL ENERGY REGULATORY COMMISSION

18 CFR Part 40

[Docket No. RM15-11-000; Order No. 830]

Reliability Standard for Transmission System Planned Performance for 

Geomagnetic Disturbance Events

(Issued September 22, 2016)

AGENCY: Federal Energy Regulatory Commission.

ACTION: Final rule.

SUMMARY: The Federal Energy Regulatory Commission (Commission) approves 

Reliability Standard TPL-007-1 (Transmission System Planned Performance for 

Geomagnetic Disturbance Events). The North American Electric Reliability Corporation 

(NERC), the Commission-certified Electric Reliability Organization, submitted 

Reliability Standard TPL-007-1 for Commission approval in response to a Commission 

directive in Order No. 779. Reliability Standard TPL-007-1 establishes requirements for 

certain registered entities to assess the vulnerability of their transmission systems to 

geomagnetic disturbance events (GMDs), which occur when the sun ejects charged 

particles that interact with and cause changes in the earth’s magnetic fields. Applicable 

entities that do not meet certain performance requirements, based on the results of their 

vulnerability assessments, must develop a plan to achieve the performance requirements. 

In addition, the Commission directs NERC to develop modifications to Reliability 

Standard TPL-007-1: (1) to modify the benchmark GMD event definition set forth in 
Docket No. RM15-11-000 - 2 -

Attachment 1 of Reliability Standard TPL-007-1, as it pertains to the required GMD 

Vulnerability Assessments and transformer thermal impact assessments, so that the 

definition is not based solely on spatially-averaged data; (2) to require the collection of 

necessary geomagnetically induced current monitoring and magnetometer data and to 

make such data publicly available; and (3) to include a one-year deadline for the 

development of corrective action plans and two and four-year deadlines to complete 

mitigation actions involving non-hardware and hardware mitigation, respectively. The 

Commission also directs NERC to submit a work plan and, subsequently, one or more 

informational filings that address specific GMD-related research areas.

EFFECTIVE DATE: This rule will become effective [INSERT DATE 60 days after 

publication in the FEDERAL REGISTER].

FOR FURTHER INFORMATION CONTACT:

Regis Binder (Technical Information) 

Office of Electric Reliability 

Federal Energy Regulatory Commission 

888 First Street, NE 

Washington, DC 20426 

Telephone: (301) 665-1601 

Regis.Binder@ferc.gov

Matthew Vlissides (Legal Information) 

Office of the General Counsel 

Federal Energy Regulatory Commission

888 First Street, NE 

Washington, DC 20426 

Telephone: (202) 502 -8408 

Matthew.Vlissides@ferc.gov

SUPPLEMENTARY INFORMATION:
156 FERC ¶ 61,215

UNITED STATES OF AMERICA

FEDERAL ENERGY REGULATORY COMMISSION

Before Commissioners: Norman C. Bay, Chairman;

 Cheryl A. LaFleur, Tony Clark,

and Colette D. Honorable.

Reliability Standard for Transmission System Planned 

Performance for Geomagnetic Disturbance Events

Docket No. RM15-11-000

ORDER NO. 830

FINAL RULE

(Issued September 22, 2016)

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

approves Reliability Standard TPL-007-1 (Transmission System Planned Performance for 

Geomagnetic Disturbance Events).1 The North American Electric Reliability 

Corporation (NERC), the Commission-certified Electric Reliability Organization (ERO), 

submitted Reliability Standard TPL-007-1 for Commission approval in response to a 

Commission directive in Order No. 779.2 Reliability Standard TPL-007-1 establishes 

requirements for certain registered entities to assess the vulnerability of their transmission 

systems to geomagnetic disturbance events (GMDs), which occur when the sun ejects 

 

1 16 U.S.C. 824o.

2 Reliability Standards for Geomagnetic Disturbances, Order No. 779, 78 FR 

30,747 (May 23, 2013), 143 FERC ¶ 61,147, reh’g denied, 144 FERC ¶ 61,113 (2013).
Docket No. RM15-11-000 - 2 -

charged particles that interact with and cause changes in the earth’s magnetic fields. 

Reliability Standard TPL-007-1 requires applicable entities that do not meet certain 

performance requirements, based on the results of their vulnerability assessments, to 

develop a plan to achieve the requirements. Reliability Standard TPL-007-1 addresses 

the directives in Order No. 779 by requiring applicable Bulk-Power System owners and 

operators to conduct initial and on-going vulnerability assessments regarding the 

potential impact of a benchmark GMD event on the Bulk-Power System as a whole and 

on Bulk-Power System components.3 In addition, Reliability Standard TPL-007-1 

requires applicable entities to develop and implement corrective action plans to mitigate 

identified vulnerabilities.4 Potential mitigation strategies identified in the proposed 

Reliability Standard include, but are not limited to, the installation, modification or 

removal of transmission and generation facilities and associated equipment.5 

Accordingly, Reliability Standard TPL-007-1 constitutes an important step in addressing 

the risks posed by GMD events to the Bulk-Power System.

2. In addition, pursuant to section 215(d)(5) of the FPA, the Commission directs 

NERC to develop modifications to Reliability Standard TPL-007-1: (1) to revise the 

 

3 See Reliability Standard TPL-007-1, Requirement R4; see also Order No. 779, 

143 FERC ¶ 61,147 at PP 67, 71.

4 See Reliability Standard TPL-007-1, Requirement R7; see also Order No. 779, 

143 FERC ¶ 61,147 at P 79.

5 See Reliability Standard TPL-007-1, Requirement R7.
Docket No. RM15-11-000 - 3 -

benchmark GMD event definition set forth in Attachment 1 of Reliability Standard TPL007-1, as it pertains to the required GMD Vulnerability Assessments and transformer 

thermal impact assessments, so that the definition is not based solely on spatiallyaveraged data; (2) to require the collection of necessary geomagnetically induced current 

(GIC) monitoring and magnetometer data and to make such data publicly available; and 

(3) to include a one-year deadline for the completion of corrective action plans and twoand four-year deadlines to complete mitigation actions involving non-hardware and 

hardware mitigation, respectively.

6

 The Commission directs NERC to submit these 

revisions within 18 months of the effective date of this Final Rule. The Commission also 

directs NERC to submit a work plan (GMD research work plan) within six months of the 

effective date of this Final Rule and, subsequently, one or more informational filings that 

address specific GMD-related research areas.

I. Background

A. Section 215 and Mandatory Reliability Standards

3. Section 215 of the FPA requires the Commission to certify an ERO to develop 

mandatory and enforceable Reliability Standards, subject to Commission review and 

approval. Once approved, the Reliability Standards may be enforced in the United States 

by the ERO, subject to Commission oversight, or by the Commission independently.7

 

6 16 U.S.C. 824o(d)(5).

7

Id. 824o(e).
Docket No. RM15-11-000 - 4 -

B. GMD Primer

4. GMD events occur when the sun ejects charged particles that interact with and 

cause changes in the earth’s magnetic fields.8 Once a solar particle is ejected, it can take 

between 17 to 96 hours (depending on its energy level) to reach earth.9 A geoelectric 

field is the electric potential (measured in volts per kilometer (V/km)) on the earth’s 

surface and is directly related to the rate of change of the magnetic fields.10 A geoelectric 

field has an amplitude and direction and acts as a voltage source that can cause GICs to 

flow on long conductors, such as transmission lines.11 The magnitude of the geoelectric 

field amplitude is impacted by local factors such as geomagnetic latitude and local earth 

conductivity.12 Geomagnetic latitude is the proximity to earth’s magnetic north and south 

poles, as opposed to earth’s geographic poles. Local earth conductivity is the ability of 

the earth’s crust to conduct electricity at a certain location to depths of hundreds of 

kilometers down to the earth’s mantle. Local earth conductivity impacts the magnitude 

 

8 North American Electric Reliability Corp., 2012 Special Reliability Assessment 

Interim Report: Effects of Geomagnetic Disturbances on the Bulk Power System at i-ii

(February 2012), http://www.nerc.com/files/2012GMD.pdf (GMD Interim Report). 

9

Id. ii.

10 Id.

11 Id.

12 NERC Petition, Ex. D (White Paper on GMD Benchmark Event Description) 

at 4.
Docket No. RM15-11-000 - 5 -

(i.e., severity) of the geoelectric fields that are formed during a GMD event by, all else 

being equal, a lower earth conductivity resulting in higher geoelectric fields.13 

C. Order No. 779

5. In Order No. 779, the Commission directed NERC, pursuant to section 215(d)(5)

of the FPA, to develop and submit for approval proposed Reliability Standards that 

address the impact of geomagnetic disturbances on the reliable operation of the BulkPower System. The Commission based its directive on the potentially severe, widespread impact on the reliable operation of the Bulk-Power System that can be caused by 

GMD events and the absence of existing Reliability Standards to address GMD events.14

6. Order No. 779 directed NERC to implement the directive in two stages. In the 

first stage, the Commission directed NERC to submit, within six months of the effective 

date of Order No. 779, one or more Reliability Standards (First Stage GMD Reliability 

Standards) that require owners and operators of the Bulk-Power System to develop and 

implement operational procedures to mitigate the effects of GMDs consistent with the 

reliable operation of the Bulk-Power System.15

7. In the second stage, the Commission directed NERC to submit, within 18 months 

of the effective date of Order No. 779, one or more Reliability Standards (Second Stage 

 

13 Id.

14 Order No. 779, 143 FERC ¶ 61,147 at P 3.

15 Id. P 2.
Docket No. RM15-11-000 - 6 -

GMD Reliability Standards) that require owners and operators of the Bulk-Power System 

to conduct initial and on-going assessments of the potential impact of benchmark GMD 

events on Bulk-Power System equipment and the Bulk-Power System as a whole. The 

Commission directed that the Second Stage GMD Reliability Standards must identify 

benchmark GMD events that specify what severity of GMD events a responsible entity 

must assess for potential impacts on the Bulk-Power System.16 Order No. 779 explained 

that if the assessments identified potential impacts from benchmark GMD events, the 

Reliability Standards should require owners and operators to develop and implement a 

plan to protect against instability, uncontrolled separation, or cascading failures of the 

Bulk-Power System, caused by damage to critical or vulnerable Bulk-Power System 

equipment, or otherwise, as a result of a benchmark GMD event. The Commission 

directed that the development of this plan could not be limited to considering operational 

procedures or enhanced training alone but should, subject to the potential impacts of the 

benchmark GMD events identified in the assessments, contain strategies for protecting 

against the potential impact of GMDs based on factors such as the age, condition, 

technical specifications, system configuration or location of specific equipment.17 Order 

No. 779 observed that these strategies could, for example, include automatically blocking 

GICs from entering the Bulk-Power System, instituting specification requirements for 

 

16 Id.

17 Id.
Docket No. RM15-11-000 - 7 -

new equipment, inventory management, isolating certain equipment that is not cost 

effective to retrofit or a combination thereof.

D. Order No. 797

8. In Order No. 797, the Commission approved Reliability Standard EOP-010-1 

(Geomagnetic Disturbance Operations).18 NERC submitted Reliability Standard EOP010-1 for Commission approval in compliance with the Commission’s directive in Order 

No. 779 corresponding to the First Stage GMD Reliability Standards. In Order 

No. 797-A, the Commission denied the Foundation for Resilient Societies’ (Resilient 

Societies) request for rehearing of Order No. 797. The Commission stated that the 

rehearing request “addressed a later stage of efforts on geomagnetic disturbances (i.e., 

NERC’s future filing of Second Stage GMD Reliability Standards) and [that Resilient 

Societies] may seek to present those arguments at an appropriate time in response to that 

filing.”19 In particular, the Commission stated that GIC monitoring requirements should 

be addressed in the Second Stage GMD Reliability Standards.20

 

18 Reliability Standard for Geomagnetic Disturbance Operations, Order No. 797, 

79 FR 35,911 (June 25, 2014), 147 FERC ¶ 61,209, reh’g denied, Order No. 797-A, 

149 FERC ¶ 61,027 (2014).

19 Order No. 797-A, 149 FERC ¶ 61,027 at P 2.

20 Id. P 27 (stating that the Commission continues “to encourage NERC to address 

the collection, dissemination, and use of geomagnetic induced current data, by NERC, 

industry or others, in the Second Stage GMD Reliability Standards because such efforts 

could be useful in the development of GMD mitigation methods or to validate GMD 

models”).
Docket No. RM15-11-000 - 8 -

E. NERC Petition and Reliability Standard TPL-007-1

9. On January 21, 2015, NERC petitioned the Commission to approve Reliability 

Standard TPL-007-1 and its associated violation risk factors and violation severity levels, 

implementation plan, and effective dates.21 NERC also submitted a proposed definition 

for the term “Geomagnetic Disturbance Vulnerability Assessment or GMD Vulnerability 

Assessment” for inclusion in the NERC Glossary of Terms (NERC Glossary). NERC 

maintains that Reliability Standard TPL-007-1 is just, reasonable, not unduly 

discriminatory or preferential and in the public interest. NERC further contends that 

Reliability Standard TPL-007-1 satisfies the directive in Order No. 779 corresponding to 

the Second Stage GMD Reliability Standards.

10. NERC states that Reliability Standard TPL-007-1 applies to planning coordinators, 

transmission planners, transmission owners and generation owners who own or whose 

planning coordinator area or transmission planning area includes a power transformer 

with a high side, wye-grounded winding connected at 200 kV or higher.

22

 NERC 

explains that the applicability criteria for qualifying transformers in Reliability Standard 

 

21 Reliability Standard TPL-007-1 is not attached to this final rule. Reliability 

Standard TPL-007-1 is available on the Commission’s eLibrary document retrieval 

system in Docket No. RM15-11-000 and on the NERC website, www.nerc.com. NERC 

submitted an errata on February 2, 2015 containing a corrected version of Exhibit A 

(Proposed Reliability Standard TPL-007-1).

22 A power transformer with a “high side wye-grounded winding” refers to a 

power transformer with windings on the high voltage side that are connected in a wye 

configuration and have a grounded neutral connection. NERC Petition at 13 n.32.
Docket No. RM15-11-000 - 9 -

TPL-007-1 are the same as that for the First Stage GMD Reliability Standard in 

Reliability Standard EOP-010-1, which the Commission approved in Order No. 797.

11. Reliability Standard TPL-007-1 contains seven requirements. Requirement R1 

requires planning coordinators and transmission planners to determine the individual and 

joint responsibilities in the planning coordinator’s planning area for maintaining models 

and performing studies needed to complete the GMD Vulnerability Assessment required 

in Requirement R4. 

12. Requirement R2 requires planning coordinators and transmission planners to 

maintain system models and GIC system models needed to complete the GMD 

Vulnerability Assessment required in Requirement R4. 

13. Requirement R3 requires planning coordinators and transmission planners to have 

criteria for acceptable system steady state voltage limits for their systems during the 

benchmark GMD event described in Attachment 1 (Calculating Geoelectric Fields for the 

Benchmark GMD Event). 

14. Requirement R4 requires planning coordinators and transmission planners to 

conduct a GMD Vulnerability Assessment every 60 months using the benchmark GMD 

event described in Attachment 1 to Reliability Standard TPL-007-1. The benchmark 

GMD event is based on a 1-in-100 year frequency of occurrence and is composed of four 

elements: (1) a reference peak geoelectric field amplitude of 8 V/km derived from 

statistical analysis of historical magnetometer data; (2) a scaling factor to account for 

local geomagnetic latitude; (3) a scaling factor to account for local earth conductivity; 

and (4) a reference geomagnetic field time series or wave shape to facilitate time-domain 
Docket No. RM15-11-000 - 10 -

analysis of GMD impact on equipment.23 The product of the first three elements is 

referred to as the regional geoelectric field peak amplitude.24

15. Requirement R5 requires planning coordinators and transmission planners to 

provide GIC flow information, to be used in the transformer thermal impact assessment 

required in Requirement R6, to each transmission owner and generator owner that owns 

an applicable transformer within the applicable planning area. 

16. Requirement R6 requires transmission owners and generator owners to conduct 

thermal impact assessments on solely and jointly owned applicable transformers where 

the maximum effective GIC value provided in Requirement R5 is 75 amperes per phase 

(A/phase) or greater. 

17. Requirement R7 requires planning coordinators and transmission planners to 

develop corrective action plans if the GMD Vulnerability Assessment concludes that the 

system does not meet the performance requirements in Table 1 (Steady State Planning 

Events).

 

23 See Reliability Standard TPL-007-1, Att. 1; see also NERC Petition, Ex. D 

(White Paper on GMD Benchmark Event Description) at 5.

24 NERC Petition, Ex. D (White Paper on GMD Benchmark Event Description) 

at 5.
Docket No. RM15-11-000 - 11 -

F. Notice of Proposed Rulemaking

18. On May 14, 2015, the Commission issued a notice of proposed rulemaking 

(NOPR) proposing to approve Reliability Standard TPL-007-1.25 In addition, the 

Commission proposed to direct that NERC develop three modifications to Reliability 

Standard TPL-007-1. First, the Commission proposed to direct NERC to revise the 

benchmark GMD event definition in Reliability Standard TPL-007-1 so that the 

definition is not based solely on spatially-averaged data. Second, the Commission 

proposed to direct NERC to revise Reliability Standard TPL-007-1 to require the 

installation of GIC monitors and magnetometers where necessary. Third, the 

Commission proposed to direct NERC to revise Reliability Standard TPL-007-1 to 

require corrective action plans (Requirement R7) to be developed within one year and, 

with respect to the mitigation actions called for in the corrective action plans, nonhardware mitigation actions to be completed within two years of finishing development 

of the corrective action plan and hardware mitigation to be completed within four years. 

The NOPR also proposed to direct NERC to submit a work plan and, subsequently, one 

or more informational filings that address specific GMD-related research areas and

sought comment on certain issues relating to the transformer thermal impact assessments 

 

25 Reliability Standard for Transmission System Planned Performance for 

Geomagnetic Disturbance Events, Notice of Proposed Rulemaking, 80 FR 29,990 

(May 26, 2015), 151 FERC ¶ 61,134 (2015) (NOPR).
Docket No. RM15-11-000 - 12 -

(Requirement R6) and the meaning of language in Table 1 of Reliability Standard TPL007-1. 

19. On August 20, 2015 and October 2, 2015, the Commission issued notices setting 

supplemental comment periods regarding specific documents. On March 1, 2016, 

Commission staff led a technical conference on Reliability Standard TPL-007-1 and 

issues raised in the NOPR.26

20. On April 28, 2016, NERC made a filing notifying the Commission that “NERC 

identified new information that may necessitate a minor revision to a figure in one of the 

supporting technical white papers. This revision would not require a change to any of the 

Requirements of the proposed Reliability Standard.”27 On June 28, 2016, NERC 

submitted the revised technical white papers referenced in the April 28, 2016 filing. On 

June 29, 2016, the Commission issued a notice setting a supplemental comment period 

regarding the revised technical white papers submitted by NERC on June 28, 2016.

21. In response to the NOPR and subsequent notices, 28 entities filed initial and 

supplemental comments. We address below the issues raised in the NOPR and

comments. The Appendix to this Final Rule lists the entities that filed comments in 

response to the NOPR and in response to the supplemental comment period notices.

 

26 Written presentations at the March 1, 2016 Technical Conference and the 

Technical Conference transcript referenced in this Final Rule are accessible through the 

Commission’s eLibrary document retrieval system in Docket No. RM15-11-000.

27 NERC April 28, 2016 Filing at 1.
Docket No. RM15-11-000 - 13 -

II. Discussion

22. Pursuant to section 215(d) of the FPA, the Commission approves Reliability 

Standard TPL-007-1 as just, reasonable, not unduly discriminatory or preferential and in 

the public interest. While we recognize that scientific and operational research regarding 

GMD is ongoing, we believe that the potential threat to the bulk electric system warrants 

Commission action at this time, including efforts to conduct critical GMD research and 

update Reliability Standard TPL-007-1 as appropriate. 

23. First, we find that Reliability Standard TPL-007-1 addresses the directives in 

Order No. 779 corresponding to the development of the Second Stage GMD Reliability 

Standards. Reliability Standard TPL-007-1 does this by requiring applicable Bulk-Power 

System owners and operators to conduct, on a recurring five-year cycle,28 initial and ongoing vulnerability assessments regarding the potential impact of a benchmark GMD 

event on the Bulk-Power System as a whole and on Bulk-Power System components.29 

In addition, Reliability Standard TPL-007-1 requires applicable entities to develop and 

implement corrective action plans to mitigate vulnerabilities identified through those 

recurring vulnerability assessments.

30

 Potential mitigation strategies identified in the 

 

28 A detailed explanation of the five-year GMD Vulnerability Assessment and 

mitigation cycle is provided in paragraph 103, infra.

29 See Reliability Standard TPL-007-1, Requirement R4; see also Order No. 779, 

143 FERC ¶ 61,147 at PP 67, 71.

30 See Reliability Standard TPL-007-1, Requirement R7; see also Order No. 779, 

143 FERC ¶ 61,147 at P 79.
Docket No. RM15-11-000 - 14 -

proposed Reliability Standard include, but are not limited to, the installation, 

modification or removal of transmission and generation facilities and associated 

equipment.31 Accordingly, Reliability Standard TPL-007-1 constitutes an important step 

in addressing the risks posed by GMD events to the Bulk-Power System. 

24. The Commission also approves the inclusion of the term “Geomagnetic 

Disturbance Vulnerability Assessment or GMD Vulnerability Assessment” in the NERC 

Glossary; Reliability Standard TPL-007-1’s associated violation risk factors and violation 

severity levels; and NERC’s proposed implementation plan and effective dates. The 

Commission also affirms, as raised for comment in the NOPR, that cost recovery for 

prudent costs associated with or incurred to comply with Reliability Standard TPL-007-1

and future revisions to the Reliability Standard will be available to registered entities.32

25. While we conclude that Reliability Standard TPL-007-1 satisfies the directives in

Order No. 779, based on the record developed in this proceeding, the Commission 

determines that Reliability Standard TPL-007-1 should be modified to reflect the new 

information and analyses discussed below, as proposed in the NOPR. Accordingly, 

pursuant to section 215(d)(5) of the FPA, the Commission directs NERC to develop and 

submit modifications to Reliability Standard TPL-007-1 concerning: (1) the calculation 

of the reference peak geoelectric field amplitude component of the benchmark GMD 

 

31 See Reliability Standard TPL-007-1, Requirement R7.

32 NOPR, 151 FERC ¶ 61,134 at P 49 n.60.
Docket No. RM15-11-000 - 15 -

event definition; (2) the collection and public availability of necessary GIC monitoring 

and magnetometer data; and (3) deadlines for completing corrective action plans and the 

mitigation measures called for in corrective action plans. The Commission directs NERC 

to develop and submit these revisions for Commission approval within 18 months of the 

effective date of this Final Rule. 

26. Furthermore, to improve the understanding of GMD events generally, the 

Commission directs NERC to submit within six months from the effective date of this 

Final Rule a GMD research work plan.

33

 Specifically, we direct NERC to: (1) further 

analyze the area over which spatial averaging should be calculated for stability studies, 

including performing sensitivity analyses on squares less than 500 km per side (e.g., 

100 km, 200 km); (2) further analyze earth conductivity models by, for example, using 

metered GIC and magnetometer readings to calculate earth conductivity and using 3-D 

readings; (3) determine whether new analyses and observations support modifying the 

use of single station readings around the earth to adjust the spatially averaged benchmark 

for latitude; (4) research, as discussed below, aspects of the required thermal impact 

assessments; and (5) in NERC’s discretion, conduct any GMD-related research areas 

generally that may impact the development of new or modified GMD Reliability 

Standards. We expect that work completed through the GMD research work plan, as 

 

33 Following submission of the GMD research work plan, the Commission will 

notice the filing for public comment and issue an order addressing its proposed content 

and schedule.
Docket No. RM15-11-000 - 16 -

well as other analyses facilitated by the increased collection and availability of GIC 

monitoring and magnetometer data directed herein, will lead to further modifications to 

Reliability Standard TPL-007-1 as our collective understanding of the threats posed by 

GMD events improves. 

27. Below we discuss the following issues raised in the NOPR and NOPR comments: 

(1) the benchmark GMD event definition described in Reliability Standard TPL-007-1, 

Attachment 1 (Calculating Geoelectric Fields for the Benchmark GMD Event); 

(2) transformer thermal impact assessments in Requirement R6; (3) GMD research work 

plan; (4) collection and public availability of GIC monitoring and magnetometer data; 

(5) completion of corrective action plans in Requirement R7; (6) meaning of 

“minimized” in Table 1 (Steady State Planning Events) of Reliability Standard TPL007-1; (7) NERC’s proposed implementation plan and effective dates; and (8) other 

issues.

A. Benchmark GMD Event Definition

NERC Petition

28. NERC states that the purpose of the benchmark GMD event is to “provide a 

defined event for assessing system performance during a low probability, high magnitude 

GMD event.”34 NERC explains that the benchmark GMD event represents “the most 

severe GMD event expected in a 100-year period as determined by a statistical analysis 

 

34 NERC Petition at 15.
Docket No. RM15-11-000 - 17 -

of recorded geomagnetic data.”35 The benchmark GMD event definition is used in the 

GMD Vulnerability Assessments and thermal impact assessment requirements of 

Reliability Standard TPL-007-1 (Requirements R4 and R6).

29. As noted above, NERC states that the benchmark GMD event definition has four 

elements: (1) a reference peak geoelectric field amplitude of 8 V/km derived from 

statistical analysis of historical magnetometer data; (2) a scaling factor to account for 

local geomagnetic latitude; (3) a scaling factor to account for local earth conductivity; 

and (4) a reference geomagnetic field time series or wave shape to facilitate time-domain 

analysis of GMD impact on equipment.36 

30. The standard drafting team determined that a 1-in-100 year GMD event would 

cause an 8 V/km reference peak geoelectric field amplitude at 60 degree geomagnetic 

latitude using Québec’s earth conductivity.37 The standard drafting team stated that:

the reference geoelectric field amplitude was determined through statistical 

analysis using ... field measurements from geomagnetic observatories in 

northern Europe and the reference (Quebec) earth model .... The Quebec 

earth model is generally resistive and the geological structure is relatively 

well understood. The statistical analysis resulted in a conservative peak 

geoelectric field amplitude of approximately 8 V/km .... The frequency of 

occurrence of this benchmark GMD event is estimated to be approximately 

1 in 100 years.38

 

35 Id.

36 NERC Petition, Ex. D (White Paper on GMD Benchmark Event Description) 

at 5.

37 Id.

38 Id. (footnotes omitted).
Docket No. RM15-11-000 - 18 -

31. The standard drafting team explained that it used field measurements taken from 

the IMAGE magnetometer chain, which covers Northern Europe, for the period 1993-

2013 to calculate the reference peak geoelectric field amplitude used in the benchmark 

GMD event definition.39 As described in NERC’s petition, the standard drafting team 

“spatially averaged” four different station groups of IMAGE data, each spanning a square 

area of approximately 500 km (roughly 310 miles) in width.40 The standard drafting 

team justified the use of spatial averaging by stating that Reliability Standard TPL-007-1 

is designed to “address wide-area effects caused by a severe GMD event, such as 

increased var absorption and voltage depressions. Without characterizing GMD on 

regional scales, statistical estimates could be weighted by local effects and suggest 

unduly pessimistic conditions when considering cascading failure and voltage 

collapse.”41

32. NERC states that the benchmark GMD event includes scaling factors to enable 

applicable entities to tailor the reference peak geoelectric field to their specific location 

 

39 Id. at 8. The International Monitor for Auroral Geomagnetic Effects (IMAGE) 

consists of 31 magnetometer stations in northern Europe maintained by 10 institutes from 

Estonia, Finland, Germany, Norway, Poland, Russia, and Sweden. See IMAGE website, 

http://space.fmi.fi/image/beta/?page=home#. 

40 As applied by the standard drafting team, spatial averaging refers to the 

averaging of geoelectric field amplitude readings within a given area. NERC Petition, 

Ex. D (White Paper on GMD Benchmark Event Description) at 9.

41 NERC Petition, Ex. D (White Paper on GMD Benchmark Event Description) 

at 9.
Docket No. RM15-11-000 - 19 -

for conducting GMD Vulnerability Assessments. NERC explains that the scaling factors 

in the benchmark GMD event definition are applied to the reference peak geoelectric 

field amplitude to adjust the 8 V/km value for different geomagnetic latitudes and earth 

conductivities.42 

33. The standard drafting team also identified a reference geomagnetic field time 

series from an Ottawa magnetic observatory during a 1989 GMD event that affected 

Québec.43 The standard drafting team used this time series to estimate a geoelectric field, 

represented as a time series (i.e., 10-second values over a period of days), that is expected 

to occur at 60 degree geomagnetic latitude during a 1-in-100 year GMD event. NERC 

explains that this time series is used to facilitate time-domain analysis of GMD impacts

on equipment.44

34. In the sub-sections below, we discuss two issues concerning the benchmark GMD 

event definition addressed in the NOPR: (1) reference peak geoelectric field amplitude; 

and (2) geomagnetic latitude scaling factor.

 

42 NERC Petition at 18-19.

43 NERC Petition, Ex. D (White Paper on GMD Benchmark Event Description) 

at 5-6, 15-16 (“the reference geomagnetic field waveshape was selected after analyzing a 

number of recorded GMD events... the March 13-14, 1989 GMD event, measured at 

NRCan’s Ottawa geomagnetic observatory, was selected as the reference geomagnetic 

field waveform because it provides generally conservative results when performing 

thermal analysis of power transformers”).

44 Id. at 5-6.
Docket No. RM15-11-000 - 20 -

1. Reference Peak Geoelectric Field Amplitude

NOPR

35. The NOPR proposed to approve the benchmark GMD event definition. The 

NOPR stated that the “benchmark GMD event definition proposed by NERC complies 

with the directive in Order No. 779 ... [c]onsistent with the guidance provided in Order 

No. 779, the benchmark GMD event definition proposed by NERC addresses the 

potential widespread impact of a severe GMD event, while taking into consideration the 

variables of geomagnetic latitude and local earth conductivity.”45 

36. In addition, the NOPR proposed to direct NERC to develop modifications to 

Reliability Standard TPL-007-1. Specifically, the NOPR proposed to direct NERC to 

modify the reference peak geoelectric field amplitude component of the benchmark GMD 

event definition so that it is not calculated based solely on spatially-averaged data. The 

NOPR explained that this could be achieved, for example, by requiring applicable entities 

to conduct GMD Vulnerability Assessments (and, as discussed below, thermal impact 

assessments) using two different benchmark GMD events: the first benchmark GMD 

event using the spatially-averaged reference peak geoelectric field value (8 V/km) and the 

second using the non-spatially averaged peak geoelectric field value cited in the GMD 

Interim Report (20 V/km). The NOPR stated that the revised Reliability Standard could 

then require applicable entities to take corrective actions, using engineering judgment, 

 

45 NOPR, 151 FERC ¶ 61,134 at P 32.
Docket No. RM15-11-000 - 21 -

based on the results of both assessments. The NOPR explained that applicable entities 

would not always be required to mitigate to the level of risk identified by the nonspatially averaged analysis; instead, the selection of mitigation would reflect the range of 

risks bounded by the two analyses, and be based on engineering judgment within this 

range, considering all relevant information. The NOPR stated that, alternatively, NERC 

could propose an equally efficient and effective modification that does not rely 

exclusively on the spatially-averaged reference peak geoelectric field value.

Comments

37. NERC does not support revising the benchmark GMD event definition. NERC 

maintains that the spatially-averaged reference peak geoelectric field amplitude value in 

Reliability Standard TPL-007-1 is “technically-justified, scientifically sound, and has 

been published in a peer-reviewed research journal covering geomagnetism and other 

topics.”46 NERC contends that the standard drafting team determined that using the nonspatially averaged 20 V/km figure in the GMD Interim Report would “consistently 

overestimate the geoelectric field of a 1-in-100 year GMD event.”47 NERC states that, by 

contrast, spatial averaging “properly associates the relevant spatial scales for the analyzed 

and applied geoelectric fields and would not distort the complexity of the potential

 

46 NERC Comments at 6.

47 Id. at 7.
Docket No. RM15-11-000 - 22 -

impacts of a GMD event.”48 NERC claims that the 500 km-wide square areas used to 

determine the areas of spatial averaging are “based on consideration of transmission 

systems and geomagnetic observation patterns ... [and are] an appropriate scale for a 

system-wide impact in a transmission system.”49 To support this position, NERC cites a 

June 2015 peer-reviewed publication authored in part by some members of the standard 

drafting team.50

38. Industry commenters, largely represented by the Trade Associations’ comments, 

do not support revising the benchmark GMD event definition.51 The Trade Associations’ 

reasons largely mirror NERC’s. While recognizing that the spatially-averaged reference 

peak geoelectric field amplitude is lower than the non-spatially averaged figure, the 

Trade Associations contend that the non-spatially averaged value is inappropriate 

because: (1) the peak geoelectric field only affects relatively small areas and quickly 

 

48 Id. at 8.

49 Id.

50 See Pulkkinen, A., Bernabeu, E., Eichner, J., Viljanen, A., Ngwira, C., 

“Regional-Scale High-Latitude Extreme Geoelectric Fields Pertaining to 

Geomagnetically Induced Currents,” Earth, Planets and Space (June 19, 2015) (2015 

Pulkkinen Paper).

51 Trade Associations Comments at 13-18. AEP, APS, ATC, BPA, CEA, Hydro 

One, ITC, Joint ISOs/RTOs and Exelon indicated that they do not support the NOPR 

proposal in separate comments and/or by joining the Trade Associations’ comments. See

AEP Comments at 3; APS Comments at 2; ATC Comments at 3; BPA Comments at 3-4; 

CEA Comments at 8-13; Hydro One Comments 1-2; ITC Comments at 3-5; Joint 

ISOs/RTOs Comments at 4-5; Exelon Comments at 2.
Docket No. RM15-11-000 - 23 -

declines with distance from the peak; (2) Reliability Standard TPL-007-1 is intended to 

address the wide-scale effects of a GMD event; and (3) the benchmark GMD event 

definition is designed to provide a realistic estimate of wide-area effects caused by a 

severe GMD event. The Trade Associations contend that a non-spatially averaged 

reference peak geoelectric field amplitude “would be weighted by local effects and 

suggest unrealistic conditions for system analysis ... [which] could lead to unnecessary 

costs for customers, while yielding very little tangible benefit to reliability.”52 Like 

NERC, the Trade Associations cite to the 2015 Pulkkinen Paper to support the use of 

500 km-wide squares in performing the spatial averaging analysis. The Trade 

Associations note, however, that the selection of 500 km is “only the beginning ... [of 

the] exploration of spatial geoelectric field structures pertaining to extreme GIC.”53

39. The Trade Associations, while not supportive of the NOPR proposal, recommend 

that if the Commission remains concerned about relying on NERC’s proposed spatiallyaveraged reference peak geoelectric field amplitude, the Commission should:

allow NERC to further determine the appropriate localized studies to be 

performed by moving the “local hot spot” around a planning area. This 

approach may better ensure that the peak values only impact a local area 

instead of unrealistically projecting uniform peak values over a broad area. 

This approach also should better align with the Commission’s concerns 

because this type of study would more accurately reflect the real-world 

impact of a GMD event on the [Bulk-Power System]. The Trade 

 

52 Trade Associations Comments at 15.

53 Id. at 17 (quoting 2015 Pulkkinen Paper at 6).
Docket No. RM15-11-000 - 24 -

Associations understand that existing planning tools may not yet have such 

capabilities, but the tools can be modified to allow such study.54

40. Industry commenters raise other concerns with the NOPR proposal. CEA states 

that it would be inappropriate to rely on the non-spatially averaged 20 V/km reference 

peak geoelectric field figure because that figure is found in a single publication. CEA 

also contends that it is impractical to use “engineering judgment” to weigh the GMD 

Vulnerability Assessments using the spatially-averaged and non-spatially averaged 

reference peak geoelectric field amplitudes, as described in the NOPR.55 ITC states that 

NERC’s proposal is reasonable and that the reference peak geoelectric field amplitude 

value can be revised periodically based on new information. Joint ISOs/RTOs state that 

the Commission should afford due weight to NERC’s technical expertise.

41. A September 2015 paper prepared by the Los Alamos National Laboratory states 

that it analyzed the IMAGE data using a different methodology to calculate reference 

peak geoelectric field amplitude values based on each of eight different magnetometer 

installations in Northern Europe. However, unlike the standard drafting team, the 

Los Alamos Paper did not spatially average the IMAGE data. The authors calculated 

peak geoelectric field amplitudes ranging from 8.4 V/km to 16.6 V/km, with a mean of 

 

54 Id. at 16. 

55 See also Hydro One Comments at 1-2; Resilient Societies Comments at 24-25. 
Docket No. RM15-11-000 - 25 -

the eight values equal to 13.2 V/km.56 The authors used a statistical formula and 

probability distribution to determine their 1-in-100 year GMD event parameters, as 

opposed to the 20 V/km non-spatially averaged event from the 2012 paper cited in the 

GMD Interim Report that visually extrapolated the data.

42. Roodman contends that “NERC’s 100-year benchmark GMD event is 

appropriately conservative in magnitude (except perhaps in the southern-most US) if 

unrealistic in some other respects.”57 Roodman states that “overall NERC’s analytical 

frame does not strongly clash with the data.”58 However, Roodman contends that actual 

data support local hot-spots in a larger region of lower magnitude geoelectric fields that 

are not typically uniform in magnitude or direction.59 Roodman addresses comments by 

Kappenman against the benchmark GMD event by stating that the Oak Ridge Report’s 

Meta-R-319 study, authored by Kappenman, modeled a 1-in-100 year GMD event based 

largely on misunderstandings of historic GMDs, both in magnitude and geographic 

 

56 Rivera, M., Backhaus, S., “Review of the GMD Benchmark Event in TPL007-1,” Los Alamos National Laboratory (September 2015) (Los Alamos Paper).

57 Roodman Comments at 4. Roodman criticizes the proposed benchmark GMD 

event definition because it assumes that the induced electrical field resulting from a GMD 

event is spatially uniform. Roodman also contends that a GMD event that is less than a 

1-in-100 year storm could potentially damage transformers. Id. at 12-14.

58 Roodman Comments at 9.

59 Id. at 10, 12-13.
Docket No. RM15-11-000 - 26 -

footprint.60 Roodman recommends that the Commission “require a much larger array of 

events for simulation” in light of the “deep uncertainty and complexity of the GMD.”61 

43. Commenters opposed to the benchmark GMD event definition proposed by NERC 

maintain that the standard drafting team significantly underestimated the reference peak 

geoelectric field amplitude value for a 1-in-100 year GMD event by relying on data from 

the IMAGE system and by applying spatial averaging to that data set.62 For example, 

Resilient Societies states that the standard drafting team should have analyzed “realworld data from within the United States and Canada, including magnetometer readings 

from the [USGS] and Natural Resources Canada observatories ... [h]ad NERC and the 

Standard Drafting Team collected and analyzed available real-world data, they would 

have likely found that the severity of GMD in 1-in-100 Year reference storm had been set 

far below a technically justified level and without a ‘strong technical basis.’”

63

 Likewise, 

Kappenman contends that there are multiple examples where the benchmark GMD event 

and the standard drafting team’s model for calculating geoelectric fields under-predict 

 

60 Id. at 5-6 (citing Oak Ridge National Laboratory, Geomagnetic Storms and 

Their Impacts on the U.S. Power Grid: Meta-R-319 at pages I-1 to I-3 (January 2010), 

http://www.ornl.gov/sci/ees/etsd/pes/pubs/ferc_Meta-R-319.pdf (Meta-R-319 Study).

61 Id. at 15.

62 See, e.g., JINSA Comments at 2; Emprimus Comments at 1. See also Gaunt 

Comments at 9 (indicating that the proposed benchmark GMD event definition may 

underestimate the effects of a 1-in-100 GMD event). 

63 Resilient Societies Comments at 20-21.
Docket No. RM15-11-000 - 27 -

actual, historical GIC readings.64 Commenters opposed to NERC’s proposal variously 

argue that the reference peak geoelectric field amplitude should be set at a level 

commensurate with the 1921 Railroad Storm or 1859 Carrington Event or at the 20 V/km 

level cited in the GMD Interim Report.65

Commission Determination

44. The Commission approves the reference peak geoelectric field amplitude figure 

proposed by NERC. In addition, the Commission, as proposed in the NOPR, directs 

NERC to develop revisions to the benchmark GMD event definition so that the reference 

peak geoelectric field amplitude component is not based solely on spatially-averaged 

data. The Commission directs NERC to submit this revision within 18 months of the 

effective date of this Final Rule. 

45. NERC and industry comments do not contain new information to support relying 

solely on spatially-averaged data to calculate the reference peak geoelectric field 

amplitude in the benchmark GMD event definition. The 2015 Pulkkinen Paper contains 

the same justifications for spatial averaging as those presented in NERC’s petition. In 

addition, the 2015 Pulkkinen Paper validates the NOPR’s concerns with relying solely on 

 

64 Kappenman Comments at 15- 29.

65 See, e.g., EIS Comments at 2 (advocating use of 20 V/km); Gaunt Comments 

at 6-9 (contending that NERC’s proposed figure results in a “possible underestimation of 

the effects of GICs” without suggesting an alternative figure); JINSA Comments at 2 

(advocating use of 20 V/km); Emprimus Comments at 1 (advocating use of 20 V/km); 

Briggs Comments at 1 (advocating that the benchmark GMD event should be a 

“Carrington Class solar superstorm”).
Docket No. RM15-11-000 - 28 -

spatial averaging generally and with the method used by the standard drafting team to 

spatially average the IMAGE data specifically. The 2015 Pulkkinen Paper, for example, 

states that “regional scale geoelectric fields have not been considered earlier from the 

statistical and extreme analyses standpoint” and “selection of an area of 500 km [for

spatial averaging] ...[is] subjective.”66 Further, the 2015 Pulkkinen Paper notes that “we 

emphasize that the work described in this paper is only the beginning in our exploration 

of spatial geoelectric field structures pertaining to extreme GIC ... [and] [w]e will ... 

expand the statistical analyses to include characterization of multiple different spatial 

scales.”67 On the latter point, NERC “agrees that such research would provide additional 

modeling insights and supports further collaborative efforts between space weather 

researchers and electric utilities through the NERC GMD Task Force.”68 These 

statements support the NOPR’s observation that the use of spatial averaging in this 

context is new, and thus there is a dearth of information or research regarding its 

application or appropriate scale. 

46. While we believe our directive addresses concerns with relying solely on spatiallyaveraged data, we reiterate the position expressed in the NOPR that a GMD event will 

have a peak value in one or more location(s) and the amplitude will decline over distance 

 

66 2015 Pulkkinen Paper at 2.

67 Id. at 6.

68 NERC Comments at 8.
Docket No. RM15-11-000 - 29 -

from the peak; and, as a result, imputing the highest peak geoelectric field value in a 

planning area to the entire planning area may incorrectly overestimate GMD impacts.69 

Accordingly, our directive should not be construed to prohibit the use of spatial averaging 

in some capacity, particularly if more research results in a better understanding of how 

spatial averaging can be used to reflect actual GMD events.

47. The NOPR proposed to direct NERC to revise Reliability Standard TPL-007-1 so 

that the reference peak geoelectric field value is not based solely on spatially-averaged 

data. NERC and industry comments largely focused on the NOPR’s discussion of one 

possible example to address the directive (i.e., by running GMD Vulnerability 

Assessments using spatially-averaged and non-spatially averaged reference peak 

geoelectric field amplitudes). However, while the method discussed in the NOPR is one

possible option, the NOPR did not propose to direct NERC to develop revisions based on 

that option or any specific option. The Trade Associations’ comments, discussed above, 

demonstrate that there is another way to address the NOPR directive (i.e., by performing 

planning models that also assess planning areas for localized “hot spots”). This approach 

may have merit if, for example, the geographic size of the hot spot is supported by actual 

data and the hot spot is centered over one or more locations that include an entity’s 

facilities that become critical during a GMD event. Without pre-judging how NERC 

proposes to address the Commission’s directive, NERC’s response to this directive

 

69 NOPR, 151 FERC ¶ 61,134 at P 35.
Docket No. RM15-11-000 - 30 -

should satisfy the NOPR’s concern that reliance on spatially-averaged data alone does not

address localized peaks that could potentially affect the reliable operation of the BulkPower System.

48. We believe our directive should also largely address the comments submitted by 

entities opposed to NERC’s proposed reference peak geoelectric field amplitude. Those 

commenters endorsed using a higher reference peak geoelectric field amplitude value, 

such as the 20 V/km cited in the GMD Interim Report. At the outset, we observe that the 

comments critical of the standard drafting team’s use of the IMAGE data only speculate 

that had the standard drafting team used other sources, the calculated reference peak 

geoelectric field amplitude value would have been higher.70 Moreover, among the 

commenters critical of NERC’s proposal, there is disagreement over the magnitude of 

historical storms which some of these commenters would use as a model.71 While NERC

has discretion on how to propose to address our directive, NERC could revise Reliability 

Standard TPL-007-1 to apply a higher reference peak geoelectric field amplitude value to 

assess the impact of localized hot spots on the Bulk-Power System, as suggested by the 

 

70 See, e.g., Resilient Societies Comments at 21 (“Had NERC and the Standard 

Drafting Team collected and analyzed available real-world data, they would have likely 

found that the severity of GMD in 1-in-100 Year reference storm had been set far below a 

technically justified level ...” (emphasis added)).

71 See, e.g., Gaunt Comments at 13 (stating that the 1859 Carrington Event is 

“probably outside the re-occurrence frequency of 1:100 years adopted by NERC for the 

benchmark event”); Briggs Comments at 1 (advocating using a “‘Carrington Class’ super 

storm” as the benchmark GMD event).
Docket No. RM15-11-000 - 31 -

Trade Associations. The effects of such hot spots could include increases in GIC levels, 

volt-ampere reactive power consumption, harmonics on the Bulk-Power System (and 

associated misoperations) and transformer heating. Moreover, the directive to revise 

Reliability Standard TPL-007-1 and, as discussed below, the directives to research

geomagnetic latitude scaling factors and earth conductivity models as part of the GMD 

research work plan and to revise Reliability Standard TPL-007-1 to require the collection 

of necessary GIC monitoring and magnetometer data to validate GMD models should 

largely address or at least help to focus-in on factors that may be causing any

inaccuracies in the standard drafting team’s model. 

49. Consistent with Order No. 779, the Commission does not specify a particular

reference peak geoelectric field amplitude value that should be applied to hot spots given 

present uncertainties. While 20 V/km would seem to be a possible value, the Los Alamos 

Paper suggests that the 20 V/km figure may be too high. The Los Alamos Paper 

analyzed the non-spatially averaged IMAGE data to calculate a reference peak 

geoelectric field amplitude range (i.e., 8.4 V/km to 16.6 V/km) that is between NERC’s 

proposed spatially-averaged value of 8 V/km and the non-spatially averaged 20 V/km 

figure cited in the GMD Interim Report.

50. Although the NOPR did not propose to direct NERC to submit revisions to 

Reliability Standard TPL-007-1 by a certain date with respect to the benchmark GMD 

event definition, the Commission determines that it is appropriate to impose an 18-month 

deadline from the effective date of this Final Rule. As discussed below, the Commission 

approves the five-year implementation period for Reliability Standard TPL-007-1
Docket No. RM15-11-000 - 32 -

proposed by NERC. Having NERC submit revisions to the benchmark GMD event 

definition within 18 months of the effective date of this Final Rule, with the Commission 

acting promptly on the revised Reliability Standard, should afford enough time to apply 

the revised benchmark GMD event definition in the first GMD Vulnerability Assessment

under the timeline set forth in Reliability Standard TPL-007-1’s implementation plan. If 

circumstances, such as the complexity of the revised benchmark GMD event, require it, 

NERC may propose and justify a revised implementation plan.

2. Geomagnetic Latitude Scaling Factor

NOPR

51. The NOPR proposed to approve the geomagnetic latitude scaling factor in 

NERC’s proposed benchmark GMD event definition. However, the NOPR sought 

comment on whether, in light of studies indicating that GMD events could have 

pronounced effects on lower geomagnetic latitudes, a modification is warranted to reduce 

the impact of the scaling factors.72

 

72 NOPR, 151 FERC ¶ 61,134 at P 37 (citing Ngwira, C. M., Pulkkinen, A., 

Kuznetsova, M. M., Glocer, A., “Modeling extreme ‘Carrington-type’ space weather 

events using three-dimensional global MHD simulations,” 119 Journal of Geophysical 

Research: Space Physics 4472 (2014) (finding that in Carrington-type events “the region 

of large induced ground electric fields is displaced further equatorward ... [and] thereby 

may affect power grids ... such as [those in] southern states of [the] continental U.S.”); 

Gaunt, C. T., Coetzee, G., “Transformer Failures in Regions Incorrectly Considered to 

have Low GIC-Risk,” 2007 IEEE Lausanne 807 (July 2007) (stating that twelve 

transformers were damaged and taken out of service in South Africa (at -40 degrees 

latitude) during the October 2003 Halloween Storm GMD event)). See also Liu, C., Li, 

Y., Pirjola, R., “Observations and modeling of GIC in the Chinese large-scale highvoltage power networks,” Journal Space Weather Space Climate 4 at A03-p6 (2014) (Liu 

(continued...)
Docket No. RM15-11-000 - 33 -

Comments

52. NERC contends that the geomagnetic latitude scaling factor in Reliability 

Standard TPL-007-1 “accurately models the reduction of induced geoelectric fields that 

occurs over the mid-latitude region during a 100-year GMD event scenario ... [and] 

describes the observed drop in geoelectric field that has been exhibited in analysis of 

major recorded geomagnetic storms.”73 NERC maintains that modifying the scaling 

factor is not technically justified based on the publications cited in the NOPR. NERC 

states that the first paper cited in the NOPR is based on models that are not mature and 

reflect a 1-in-150 year storm. NERC contends that the second paper does not clearly 

show that the purported transformer damage in South Africa was the result of abnormally 

high GICs during the October 2003 Halloween Storm. NERC further states that the 

standard drafting team analyzed the October 2003 Halloween Storm when developing the 

proposed geomagnetic latitude scaling factor.

53. The Trade Associations support the geomagnetic latitude scaling factor proposed 

by NERC. Like NERC, the Trade Associations contend that the papers cited in the 

NOPR do not support modifications because the models in the first paper “remain highly 

 

Paper), http://www.swsc-journal.org/articles/swsc/pdf/2014/01/ swsc130009.pdf (finding 

that GICs of about 25A/phase had been measured in a transformer at a nuclear power 

plant at 22.6 degrees north latitude (significantly further away from the magnetic pole 

than Florida)). 

73 NERC Comments at 9 (citing Ngwira, C., Pulkkinen, A., Wilder, F., Crowley, 

G., “Extended Study of Extreme Geoelectric Field Event Scenarios for Geomagnetically 

Induced Current Applications,” 11 Space Weather 121 (2013) (Ngwira 2013 Paper)).
Docket No. RM15-11-000 - 34 -

theoretical and not sufficiently validated” and because the second paper likely involved 

other causal factors leading to the transformer failure.74 Joint ISOs/RTOs also support 

the geomagnetic latitude scaling factor proposed by NERC. ITC states that NERC’s 

proposal is a “reasonable approach given the current state of the science pertaining to 

GMD ... [but] that as the science pertaining to GMD matures and more data becomes 

available, the scaling factors should be revisited and revised.”75 ITC suggests revisiting 

the geomagnetic latitude scaling factor every five years to incorporate any new 

developments in GMD science.

54. Several commenters question or disagree with the geomagnetic latitude scaling 

factors in Reliability Standard TPL-007-1 based on simulations and reports of damage to 

transformers in areas expected to be at low risk due to their geomagnetic latitude.76 EIS 

contends that the proposed geomagnetic latitude scaling factor’s assumption of a storm 

centered at 60 degrees geomagnetic latitude is inconsistent with a study relied upon by 

NERC.77 The Los Alamos Paper’s analysis suggests that NERC’s proposed geomagnetic 

latitude scaling factors, while they fit well with weaker historical GMD events from 

 

74 Trade Associations Comments at 18-19.

75 Joint ISOs/RTOs Comments at 5.

76 See, e.g., Gaunt Comments at 6; JINSA Comments at 2; Emprimus Comments 

at 2-3; Roodman Comments at 9; Resilient Societies Comments at 31-31; Kappenman 

Comments at 41-42.

77 EIS Comments at 5 (citing Ngwira 2013 Paper).
Docket No. RM15-11-000 - 35 -

which they were derived, may not accurately represent the effects of a 1-in-100 year 

GMD event at lower geomagnetic latitudes. The Los Alamos Paper states that a model of 

the electrojet is needed to “effectively extrapolate the small to moderate disturbance data 

currently in the historical record to disturbances as large as the TPL-007-1 Benchmark 

Event.”78 The Los Alamos Paper uses a larger number of geomagnetic disturbances (122 

instead of 12) and a wider range of observatories by using the world-wide SuperMAG 

magnetometer array data, which includes the INTERMAGNET data used to support 

NERC’s geomagnetic latitude scaling factors. The Los Alamos Paper shows that for 

more severe storms (Dst < -300, for which there are nine storms in the data set) the 

NERC scaling factors tend to be low, off by a factor of up to two or three at some 

latitudes. The Los Alamos Paper also recommends “an additional degree of conservatism 

in the mid-geomagnetic latitudes” until such time as a model is developed.79 The 

Los Alamos Paper authors recommend a factor of 2 as a conservative correction.

Commission Determination

55. The Commission approves the geomagnetic latitude scaling factor in the 

benchmark GMD event definition. In addition, the Commission directs NERC to conduct 

further research on geomagnetic latitude scaling factors as part of the GMD research

work plan discussed below.

 

78 Los Alamos Paper at 12.

79 Id.
Docket No. RM15-11-000 - 36 -

56. Based on the record, the Commission finds sufficient evidence to conclude that 

lower geomagnetic latitudes are, to some degree, less susceptible to the effects of GMD 

events. The issue identified in the NOPR and by some commenters focused on the 

specific scaling factors in Reliability Standard TPL-007-1 in light of some analyses and 

anecdotal evidence suggesting that lower geomagnetic latitudes may be impacted by 

GMDs to a larger degree than reflected in Reliability Standard TPL-007-1. 

57. The geomagnetic latitude scaling factor in Reliability Standard TPL-007-1 is 

supported by some of the available research.80 In addition, with the exception of the 

Los Alamos Paper, commenters did not provide new information on the proposed scaling 

factor nor did commenters suggest alternative scaling factors. However, the Commission 

finds that there are enough questions regarding the effects of GMDs at lower 

geomagnetic latitudes to warrant directing NERC to study this issue further as part of the 

GMD research work plan. The Los Alamos Paper and the sources cited in the NOPR are 

suggestive that a 1-in-100 year GMD event could have a greater impact on lower 

 

80 See NERC Comments at 9 (citing Ngwira 2013 Paper). We disagree with the 

contention made by EIS that NERC’s proposed geomagnetic latitude scaling factors are 

inconsistent with the Ngwira 2013 Paper. EIS maintains that the Ngwira 2013 Paper 

supports the conclusion that the benchmark GMD event should be centered at 50 degrees 

geomagnetic latitude instead of the 60 degree geomagnetic latitude figure in Reliability 

Standard TPL-007-1. The Ngwira 2013 Paper contains no such conclusion. Instead, the 

Ngwira 2013 Paper found that the latitude threshold boundary is a transition region 

having a definite lower bound of 50 degrees geomagnetic latitude but with an upper range 

as high as 55 degrees geomagnetic latitude. Ngwira 2013 Paper at 127, 130. The Ngwira 

2013 Paper also stated that its findings were “in agreement with earlier observations by 

[Thomson et al., 2011] and more recently by [Pulkkinen et al., 2012], which estimated 

the location to be within 50 [degrees]–62 [degrees].” Id. at 124.
Docket No. RM15-11-000 - 37 -

geomagnetic latitudes than NERC’s proposed scaling factor assumes. But, as the 

Los Alamos Paper recognizes, the current absence of historical data on large GMD events 

precludes a definitive conclusion based on an empirical analysis of historical 

observations. Moreover, in prepared comments for the March 1, 2016 Technical 

Conference, Dr. Backhaus, one of the authors of the Los Alamos Paper, recommended 

that “the current NERC analysis should be adopted and further analysis performed with 

additional observational data and severe disturbance modeling efforts with the intent of 

refining the geomagnetic latitude scaling law in future revisions.”81 The Commission 

directs NERC to reexamine the geomagnetic latitude scaling factors in Reliability 

Standard TPL-007-1 as part of the GMD research work plan, including using existing 

models and developing new models to extrapolate from historical data on small to 

moderate GMD events the impacts of a large, 1-in-100 year GMD event on lower 

geomagnetic latitudes.

B. Thermal Impact Assessments

NERC Petition

58. Reliability Standard TPL-007-1, Requirement R6 requires owners of transformers 

that are subject to the Reliability Standard to conduct thermal analyses to determine if the 

transformers would be able to withstand the thermal effects associated with a benchmark 

GMD event. NERC states that transformers are exempt from the thermal impact 

 

81 Statement of Scott Backhaus, March 1, 2016 Technical Conference at 2.
Docket No. RM15-11-000 - 38 -

assessment requirement if the maximum effective GIC in the transformer is less than 

75 A/phase during the benchmark GMD event as determined by an analysis of the

system. NERC explains that “based on available power transformer measurement data, 

transformers with an effective GIC of less than 75 A/phase during the Benchmark GMD 

Event are unlikely to exceed known temperature limits established by technical 

organizations.”

82

 

59. As provided in Requirements R5 and R6, “the maximum GIC value for the worst 

case geoelectric field orientation for the benchmark GMD event described in 

Attachment 1” determines whether a transformer satisfies the 75 A/phase threshold. If 

the 75 A/phase threshold is satisfied, Requirement R6 states, in relevant part, that a 

thermal impact assessment should be conducted on the qualifying transformer based on 

the effective GIC flow information provided in Requirement R5.

60. In its June 28, 2016 filing, NERC states that it identified an error in Figure 1 

(Upper Bound of Peak Metallic Hot Spot Temperatures Calculated Using the Benchmark 

GMD Event) of the White Paper on Screening Criterion for Transformer Thermal Impact 

Assessment that resulted in incorrect plotting of simulated power transformer peak hotspot heating from the benchmark GMD event. NERC revised Figure 1 in the White 

Paper on Screening Criterion for Transformer Thermal Impact Assessment and made 

corresponding revisions to related text, figures and tables throughout the technical white 

 

82 NERC Petition at 30. 
Docket No. RM15-11-000 - 39 -

papers supporting the proposed standard. NERC maintains that even with the revision to 

Figure 1, “the standard drafting team determined that the 75 A per phase threshold for 

transformer thermal impact assessment remains a valid criterion ... [and] it is not 

necessary to revise any Requirements of the proposed Reliability Standard.”83

NOPR

61. The NOPR proposed to approve the transformer thermal impact assessments in 

Requirement R6. In addition, as with the benchmark GMD event definition, the NOPR 

proposed to direct NERC to revise Requirement R6 to require registered entities to apply 

spatially averaged and non-spatially averaged peak geoelectric field values, or some 

equally efficient and effective alternative, when conducting thermal impact assessments. 

The NOPR also noted that Requirement R6 does not use the maximum GIC-producing

orientation to conduct the thermal assessment for qualifying transformers; instead, the 

requirement uses the effective GIC time series described in Requirement R5.2 to conduct 

the thermal assessment on qualifying transformers. The NOPR sought comment from 

NERC as to why qualifying transformers are not assessed for thermal impacts using the 

maximum GIC-producing orientation and directed NERC to address whether, by not 

using the maximum GIC-producing orientation, the required thermal impact assessments 

could underestimate the impact of a benchmark GMD event on a qualifying transformer.

 

83 NERC June 28, 2016 Filing at 1.
Docket No. RM15-11-000 - 40 -

Comments

62. NERC opposes modifying the thermal impact assessments in Requirement R6 so 

that the assessments do not rely only on spatially-averaged data. NERC claims that the 

benchmark GMD event definition will “result in GIC calculations that are appropriately 

scaled for system-wide assessments.”84 NERC also contends that the “analysis 

performed by the standard drafting team of the impact of localized enhanced geoelectric 

fields on the GIC levels in transformers indicates that relatively few transformers in the 

system are affected.”85 In response to the question in the NOPR of why qualifying 

transformers are not assessed for thermal impacts using the maximum GIC producing 

orientation, NERC states that “the orientation of the geomagnetic field varies widely and 

continuously during a GMD event ... [and] would be aligned with the maximum GICproducing orientation for only a few minutes.”86

 NERC concludes that “[i]n the context 

of transformer hot spot heating with time constants in the order of tens of minutes, 

alignment with any particular orientation for a few minutes at a particular point in time is 

not a driving concern.”87 NERC further states that the wave shape used in Reliability 

 

84 NERC Comments at 17.

85 Id.

86 Id. at 19.

87 Id.
Docket No. RM15-11-000 - 41 -

Standard TPL-007-1 provides “generally conservative results when performing thermal 

analysis of power transformers.”88

63. The Trade Associations and CEA do not support the proposed NOPR directive 

because, they state, it focuses too heavily on individual transformers. The Trade 

Associations maintain that Reliability Standard TPL-007-1 “was never intended to 

address specific localized areas that might experience peak conditions and affect what we 

understand to be a very small number of assets that are unlikely to initiate a cascading 

outage.”89

64. Certain non-industry commenters contend that the 75 A/phase qualifying threshold 

for thermal impact assessments is not technically justified. Emprimus contends that 

“many transformers have GIC ratings less than 75 amps per phase,” but Emprimus claims 

that an Idaho National Lab study showed that “GIC introduced at 10 amps per phase on 

high voltage transformers exceed harmonic levels allowed under IEEE 519.”90 

Emprimus also maintains that a 2013 IEEE paper “suggest[s] that there can be generator 

rotor damage at GIC levels which exceed 50 amps per phase.”91 Gaunt contends, based 

on his analysis of historical events, that “degradation is initiated in transformers by 

 

88 Id.

89 Trade Associations Comments at 21.

90 Emprimus Comments at 4. 

91 Id.
Docket No. RM15-11-000 - 42 -

currents that are significantly below the 75 amps per phase.”92 Gaunt states that “[u]ntil 

better records are kept of transformer [dissolved gas in oil analysis] and transformer 

failure, the proposed level of 75 [A/phase] of GIC needed to initiate assessment of 

transformer response must be considered excessively high.”93 Gaunt recommends a 

qualifying threshold of 15 amps per phase. Resilient Societies states that the 75 A/phase

threshold is based on a mathematical model for one type of transformer and that several 

tests referenced in the standard drafting team’s White Paper on Transformer Thermal 

Impact Assessment were carried out under no load or minimal load conditions. In 

addition, Resilient Societies contends that applying the 75 A/phase threshold and 

NERC’s proposed benchmark GMD event (i.e., using the spatially-averaged reference 

peak geoelectric field amplitude) results in only “two out of approximately 560 extra high 

voltage transformers” requiring thermal impact assessments in the PJM region; only one 

345 kV transformer requiring thermal impact assessment in Maine; and zero transformers 

requiring thermal impact assessments in ATC’s network.94 Kappenman contends that the 

 

92 Gaunt Comments at 13.

93 Id. at 14.

94 Resilient Societies Comments at 5-14. Resilient Societies states that modeling 

performed by Central Maine Power Co. and Emprimus for the Maine Public Utilities 

Commission indicates that eight 345 kV transformers (53 percent according to Resilient 

Societies) would require thermal impact assessments in Maine if the reference peak 

geoelectric field amplitude were set at 20 V/km. Id. at 10. Resilient Societies also 

contends that this result is consistent with the Oak Ridge Meta-R-319 Study’s finding 

that eight transformers would be “at risk” in Maine under a “‘30 Amp At-Risk Threshold 

scenario.’” Id. Central Maine Power Co. calculated that the scaled NERC benchmark 

(continued...)
Docket No. RM15-11-000 - 43 -

75 A/phase threshold does not consider transformers with tertiary windings or 

autotransformers which may be impacted at lower GIC levels than 75 A/phase.95 

Commission Determination

65. Consistent with our determination above regarding the reference peak geoelectric 

field amplitude value, the Commission directs NERC to revise Requirement R6 to require 

registered entities to apply spatially averaged and non-spatially averaged peak geoelectric 

field values, or some equally efficient and effective alternative, when conducting thermal 

impact assessments.

66. In the NOPR, the Commission requested comment from NERC regarding why 

Requirement R6 does not use the maximum GIC-producing orientation to conduct the 

thermal assessment for qualifying transformers. After considering NERC’s response, we 

continue to have concerns with not using the maximum GIC-producing orientation for the 

thermal assessment of transformers. However, at this time we do not direct NERC to 

modify Reliability Standard TPL-007-1. Instead, as part of the GMD research work plan 

discussed below, NERC is directed to study this issue to determine how the geoelectric 

field time series can be applied to a particular transformer so that the orientation of the 

 

GMD event for the northernmost point in Maine would be 4.53 V/km. Resilient 

Societies’ calculations regarding ATC estimate that the scaled benchmark GMD event for 

Wisconsin would be 2 V/km. Id. at 14.

95 The Commission received two comments following NERC’s June 28, 2016 

Filing. However, the supplemental comments did not specifically address the revisions 

submitted in NERC’s June 28, 2016 filing.
Docket No. RM15-11-000 - 44 -

time series, over time, will maximize GIC flow in the transformer, and to include the 

results in a filing with the Commission. 

67. We are not persuaded by the comments opposed to Requirement R6’s application

of a 75 A/phase qualifying threshold. The standard drafting team’s White Paper on 

Thermal Screening Criterion, as revised by NERC in the June 28, 2016 Filing, provides 

an adequate technical basis to approve NERC’s proposal. As noted in the revised White 

Paper on Thermal Screening Criterion, the calculated metallic hot spot temperature 

corresponding to an effective GIC of 75 A/phase is 172 degrees Celsius; that figure is

higher than the original figure of 150 degrees Celsius calculated by the standard drafting 

team but is still below the 200 degree Celsius limit specified in IEEE Std C57.91-2011.96 

The comments, particularly those of Gaunt, attempt to correlate historical transformer 

failures to past GMD events (e.g., 2003 Halloween Storm), while arguing that the 

transformers damaged in those events did not experience GICs of 75 A/phase. The 

evidence adduced by Gaunt and others is inconclusive.97 We therefore direct NERC to 

include further analysis of the thermal impact assessment qualifying threshold in the 

GMD research work plan. 

 

96 NERC June 28, 2016 Filing, Revised White Paper on Screening Criterion for 

Transformer Thermal Impact Assessment at 3.

97 See, e.g., Gaunt Comments at 13 (“Although it has not been possible to 

assemble an exact model of the power system during the period 29-31 October 2003, and 

data on the ground conductivity in Southern Africa is not known with great certainty, we 

are confident that the several calculations of GIC that been carried out are not grossly 

inaccurate.”).
Docket No. RM15-11-000 - 45 -

68. In NOPR comments and in comments to the standard drafting team, Kappenman 

stated that delta winding heating due to harmonics has not been adequately considered by 

the standard drafting team and that, thermally, this is a bigger concern than metallic hot 

spot heating.98 The standard drafting team responded that the vulnerability described for 

tertiary winding harmonic heating is based on the assumption that delta winding currents 

can be calculated using the turns ratio between primary and tertiary winding, which is 

incorrect when a transformer is under saturation.99 The standard drafting team concluded

that Kappenman’s concerns regarding delta windings being a problem from a thermal 

standpoint are unwarranted and that the criteria developed by the standard drafting team 

use state-of-the-art analysis methods and measurement-supported transformer models. 

The Commission believes that the heating effects of harmonics on transformers, as 

discussed at the March 1, 2016 Technical Conference, are of concern and require further 

research.100 Accordingly, we direct NERC to address the effects of harmonics, including 

 

98 Kappenman Comments at 45.

99 Consideration of Comments Project 2013-03 Geomagnetic Disturbance 

Mitigation at 39 (December 5, 2014), 

http://www.nerc.com/pa/Stand/Project201303GeomagneticDisturbanceMitigation/Comm

ent%20Report%20_2013-03_GMD_12052014.pdf.

100 At the March 1, 2016 Technical Conference, Dr. Horton, a member of the 

standard drafting team, discussed the potential negative impacts of harmonics generated 

by GMDs on protection systems, reactive power resources and generators. Slide 

Presentation of Randy Horton, March 1, 2016 Technical Conference at 2-6.
Docket No. RM15-11-000 - 46 -

tertiary winding harmonic heating and any other effects on transformers, as part of the 

GMD research work plan.101

C. GMD Research Work Plan

NOPR

69. The NOPR proposed to address the need for more data and certainty regarding

GMD events and their potential effect on the Bulk-Power System by directing NERC to 

submit informational filings that address GMD-related research areas. The NOPR 

proposed to direct NERC to submit in the first filing a GMD research work plan 

indicating how NERC plans to: (1) further analyze the area over which spatial averaging 

should be calculated for stability studies, including performing sensitivity analyses on 

squares less than 500 km per side (e.g., 100 km, 200 km); (2) further analyze earth 

conductivity models by, for example, using metered GIC and magnetometer readings to 

calculate earth conductivity and using 3-D readings; (3) determine whether new analyses 

and observations support modifying the use of single station readings around the earth to 

adjust the spatially averaged benchmark for latitude; and (4) assess how to make GMD 

data (e.g., GIC monitoring and magnetometer data) available to researchers for study. 

70. With respect to GIC monitoring and magnetometer readings, the NOPR sought

comment on the barriers, if any, to public dissemination of such readings, including if 

 

101 NERC indicated in its comments that it is already studying the issue of 

harmonics. NERC Comments at 14 (“NERC is collaborating with researchers to examine 

more complex GMD vulnerability issues, such as harmonics and mitigation assessment 

techniques, to enhance the modeling capabilities of the industry”).
Docket No. RM15-11-000 - 47 -

their dissemination poses a security risk and if any such data should be treated as Critical 

Energy Infrastructure Information or otherwise restricted to authorized users. The NOPR 

proposed that NERC submit the GMD research work plan within six months of the 

effective date of a final rule in this proceeding. The NOPR also proposed that the GMD 

research work plan submitted by NERC should include a schedule for submitting one or 

more informational filings that apprise the Commission of the results of the four 

additional study areas, as well as any other relevant developments in GMD research, and 

should assess whether Reliability Standard TPL-007-1 remains valid in light of new 

information or whether revisions are appropriate. 

Comments

71. NERC states that continued GMD research is necessary and that the potential 

impacts of GMDs on reliability are evolving. NERC, however, prefers that the NERC 

GMD Task Force continue its research without the GMD research work plan proposed in 

the NOPR. NERC contends that allowing the NERC GMD Task Force to continue its 

work would “accomplish NERC’s and the Commission’s shared goals in advancing 

GMD understanding and knowledge, while providing the flexibility necessary for NERC 

to work effectively with its international research partners to address risks to the 

reliability of the North American Bulk-Power System.”102 NERC also claims that, in 

addition to being unnecessary given the work of the NERC GMD Task Force, the NOPR 

 

102 NERC Comments at 13.
Docket No. RM15-11-000 - 48 -

proposal “poses practical challenges ... [because it would] bind[] NERC to a specific and 

inflexible research plan and report schedule to be determined six months (or even a year)

following the effective date of a final rule in this proceeding.”103

72. The Trade Associations and CEA do not support the GMD research work plan. 

Instead, they contend that NERC should be allowed to pursue GMD research 

independently. 

73. Several commenters, while not addressing the NOPR proposal specifically, state 

that additional research is necessary to validate or improve elements of the benchmark 

GMD event definition.104

74. The Trade Associations state that monitoring data should be available for 

academic research purposes. Resilient Societies contends that monitoring data should be 

publicly disseminated on a regular basis and that there is no security risk in releasing 

such data because they relate to naturally occurring phenomena. Emprimus states that it 

supports making GIC and magnetometer monitoring data available to the public. Bardin 

supports making GIC and GMD-related information to the public or at least to 

“legitimate researchers.”

 

103 Id. at 16.

104 See, e.g., USGS Comments at 1 (addressing earth conductivity models), Bardin 

Comments at 2 (addressing earth conductivity models); Roodman Comments at 3 

(addressing reference peak geoelectric field amplitude); Gaunt Comments at 7 

(addressing spatial averaging).
Docket No. RM15-11-000 - 49 -

75. Hydro One and CEA do not support mandatory data sharing without the use of 

non-disclosure agreements.

Commission Determination

76. The Commission recognizes, as do commenters both supporting and opposing 

proposed Reliability Standard TPL-007-1, that our collective understanding of the threats 

posed by GMD is evolving as additional research and analysis are conducted. These 

ongoing efforts are critical to the nation’s long-term efforts to protect the grid against a 

major GMD event. While we approve NERC’s proposed Reliability Standard TPL-007-1 

and direct certain modifications, as described above, the Commission also concludes that 

facilitating additional research and analysis is necessary to adequately address these 

threats. As discussed in the next two sections of this final rule, the Commission directs a 

three-prong approach to further those efforts by directing NERC to: (1) develop, submit, 

and implement a GMD research work plan; (2) develop revisions to Reliability Standard 

TPL-007-1 to require responsible entities to collect GIC monitoring and magnetometer 

data; and (3) collect GIC monitoring and magnetometer data from registered entities for 

the period beginning May 2013, including both data existing as of the date of this order 

and new data going forward, and to make that information available.

77. First, the Commission adopts the NOPR proposal and directs NERC to submit a 

GMD research work plan and, subsequently, informational filings that address the GMDrelated research areas identified in the NOPR, additional research tasks identified in this 

Final Rule (i.e., the research tasks identified in the thermal impact assessment discussion 

above) and, in NERC’s discretion, any GMD-related research areas generally that may 
Docket No. RM15-11-000 - 50 -

impact the development of new or modified GMD Reliability Standards.

105 The GMD 

research work plan should be submitted within six months of the effective date of this 

final rule. The research required by this directive should be informed by ongoing GMDrelated research efforts of entities such as USGS, National Atmospheric and Oceanic 

Administration (NOAA), National Aeronautics and Space Administration, Department of 

Energy, academia and other publicly available contributors, including work performed 

for the National Space Weather Action Plan.106 

78. As part of the second research area identified in the NOPR (i.e., further analyze 

earth conductivity models by, for example, using metered GIC and magnetometer 

readings to calculate earth conductivity and using 3-D readings), the GMD research work 

plan should specifically investigate “coastal effects” on ground conductivity models.

79. In addition, the large variances described by USGS in actual 3-D ground 

conductivity data raise the question of whether one time series geomagnetic field is 

sufficient for vulnerability assessments. The characteristics, including frequencies, of the 

time series interact with the ground conductivity to produce the geoelectric field that 

 

105 The GMD research work plan need not address the fourth research area 

identified in the NOPR (i.e., assess how to make GIC monitoring and magnetometer data

available to researchers for study) given the Commission’s directive and discussion 

below regarding the collection and dissemination of necessary GIC monitoring and 

magnetometer data. 

106 National Science and Technology Council, National Space Weather Action 

Plan (October 2015), 

https://www.whitehouse.gov/sites/default/files/microsites/ostp/final_nationalspaceweathe

ractionplan_20151028.pdf.
Docket No. RM15-11-000 - 51 -

drives the GIC. Therefore, the research should address whether additional realistic time 

series should be selected to perform assessments in order to capture the time series that 

produces the most vulnerability for an area.

80. The comments largely agree that additional GMD research should be pursued, 

particularly with respect to the elements of the benchmark GMD event definition (i.e., the 

reference peak geoelectric field amplitude value, geomagnetic latitude scaling factor, and 

earth conductivity scaling factor). There is ample evidence in the record to support the 

need for additional GMD-related research.107 For example, USGS submitted comments 

indicating that USGS’s one dimensional ground electrical conductivity models used by 

the standard drafting team have a “significant limitation” in that they assume that a “[one 

dimensional] conductivity-with-depth profile can adequately represent a large geographic 

region,” which USGS describes as a “gross simplification.”108 USGS observes that while 

the “proposed standard attempted to incorporate the best scientific research available ... it 

must be noted that the supporting science is quickly evolving.”109 USGS recommends 

that “the proposed standard should establish a process for updates and improvements that 

 

107 See, e.g., NERC October 22, 2015 Supplemental Comments at 7-8 (expressing 

support for additional research regarding geomagnetic latitude scaling factors and earth 

conductivity models).

108 USGS Comments at 1.

109 Id.
Docket No. RM15-11-000 - 52 -

acknowledges and addresses the quickly evolving nature of relevant science and 

associated data.”110 

81. Opposition to the proposal centers on the contention that the proposed directive is 

unnecessary and potentially counterproductive given the continuing work of the NERC 

GMD Task Force. We do not find these comments persuasive. Our directive requires

NERC to submit a work plan for the study of GMD-related issues that are already being 

examined or that NERC agrees should be studied.111 Nothing in our directive precludes 

NERC from continuing to use the NERC GMD Task Force as a vehicle for conducting 

the directed research or other research. Indeed, we encourage NERC to continue to use 

 

110 Id. We note that Reliability Standard TPL-007-1, Att. 1 (Calculating 

Geoelectric Fields for the Benchmark GMD Event) already provides that a “planner can 

also use specific earth model(s) with documented justification...” Accordingly, 

Reliability Standard TPL-007-1 includes a mechanism for incorporating improvements in 

earth conductivity models when calculating the benchmark GMD event.

111 See, e.g., NERC Comments at 8 (“NERC agrees that [spatial averaging] 

research would provide additional modeling insights and supports further collaborative 

efforts between space weather researchers and electric utilities through the NERC GMD 

Task Force”), at 10 (“NERC agrees that additional [geomagnetic latitude scaling] 

research is necessary, and supports the significant research that is occurring throughout 

the space weather community to develop and validate models and simulation 

techniques”), at 13 (“Working with EPRI, researchers at USGS, and industry, NERC will 

work to improve the earth conductivity models that are a vital component to 

understanding the risks of GMD events in each geographic region”), and at 23 (“efforts 

are already underway to expand GMD monitoring capabilities ... [and] [t]hrough these 

efforts, NERC and industry should effectively address the concerns noted by the 

Commission in the NOPR, including ensuring a more complete set of data for operational 

and planning needs and supporting analytical validation and situational awareness”).
Docket No. RM15-11-000 - 53 -

the GMD Task Force as a forum for engagement with interested stakeholders. In 

addition, we do not set specific deadlines for completion of the research; we only require

NERC to submit the GMD research work plan within six months of the effective date of a 

final rule. The GMD research work plan, in turn, should include target dates for the 

completion of research topics and the reporting of findings to the Commission. The 

Commission intends to notice and invite comment on the GMD research work plan. An 

extension of time to submit the GMD research work plan may be available if six months 

proves to be insufficient. In addition, given the uncertainties commonly associated with

complex research projects, the Commission will be flexible regarding changes to the

tasks and target dates established in the GMD research work plan.

D. Monitoring Data

NERC Petition

82. Reliability Standard TPL-007-1, Requirement R2 requires responsible entities to 

“maintain System models and GIC System models of the responsible entity’s planning 

area for performing the study or studies needed to complete GMD Vulnerability 

Assessment(s).” NERC states that Reliability Standard TPL-007-1 contains 

“requirements to develop the models, studies, and assessments necessary to build a 

picture of overall GMD vulnerability and identify where mitigation measures may be 

necessary.”112 NERC explains that mitigating strategies “may include installation of 

 

112 NERC Petition at 13.
Docket No. RM15-11-000 - 54 -

hardware (e.g., GIC blocking or monitoring devices), equipment upgrades, training, or 

enhanced Operating Procedures.”113

NOPR

83. The NOPR proposed to direct NERC to revise Reliability Standard TPL-007-1 to 

require the installation of monitoring equipment (i.e., GIC monitors and magnetometers) 

to the extent there are any gaps in existing GIC monitoring and magnetometer networks. 

Alternatively, the NOPR sought comment on whether NERC should be responsible for 

installation of any additional, necessary magnetometers while affected entities would be 

responsible for installation of additional, necessary GIC monitors. The NOPR also 

proposed that, as part of NERC’s work plan, NERC identify the number and location of 

current GIC monitors and magnetometers in the United States to assess whether there are 

any gaps. The NOPR sought comment on whether the Commission should adopt a policy 

specifically allowing recovery of costs associated with or incurred to comply with 

Reliability Standard TPL-007-1, including for the purchase and installation of monitoring 

devices. 

Comments

84. NERC does not support the NOPR proposal regarding the installation of GIC 

monitoring devices and magnetometers. NERC contends that the proposed requirement 

is not necessary because Reliability Standard TPL-007-1 “supports effective GMD 

 

113 Id. at 32.
Docket No. RM15-11-000 - 55 -

monitoring programs, and additional efforts are planned or underway to ensure adequate 

data for reliability purposes.”114 NERC also maintains that the proposed directive “poses 

implementation challenges ... [because] GMD monitoring capabilities and technical 

information have not yet reached a level of maturity to support application in a Reliability 

Standard, and not all applicable entities have developed the comprehensive understanding 

of system vulnerabilities that would be needed to deploy GMD monitoring devices for 

the greatest reliability benefit.”115 NERC also notes that a requirement mandating the 

installation of monitoring devices for situational awareness purposes would be outside 

the scope of a planning Reliability Standard.

85. The Trade Associations, CEA, ITC, Hydro One and Tri-State, while agreeing that 

more data are useful to analytical validation and situational awareness, do not support the 

NOPR proposal. CEA does not support the proposal because Reliability Standard TPL007-1 is a planning standard; a one-size-fits-all monitoring approach will not work; the 

responsibility for monitoring, which in Canada is done by the Canadian government, 

should not fall to industry or NERC; and the proposal is too costly. Likewise, ITC 

contends that it would not be prudent or cost effective for entities to have to install 

 

114 NERC Comments at 21. NERC cites as examples the 40 GIC monitoring 

nodes operated by EPRI’s SUNBURST network; the use of GIC monitoring devices by 

some registered entities (e.g., PJM); and the magnetometer networks operated by USGS 

and EPRI. Id. at 23-25.

115 Id.
Docket No. RM15-11-000 - 56 -

monitoring equipment. Hydro One does not support a Reliability Standard that 

prescribes the number and location of monitoring devices that must be installed. The 

Trade Associations and ITC, instead, support directing NERC to develop a plan to 

address this issue. The Trade Associations state that such a plan should involve a 

partnership between government and industry. Tri-State maintains that NERC, working 

with USGS and NOAA, should be responsible for determining the need for and 

installation of any needed magnetometers. If the Commission requires applicable entities 

to install monitoring devices, the Trade Associations, Tri-State and Exelon agree that 

there should be cost recovery. 

86. BPA supports the NOPR proposal for increased monitoring because BPA believes 

it will improve situational awareness. As a model, BPA states that the “Canadian 

government in collaboration with Canadian transmission owners” have developed a 

“technique that shows real promise of increasing visibility of GIC flows and localized 

impacts for a regional transmission grid.”116 AEP encourages the Commission to expand 

the “number and scope of the permanent geomagnetic observatories and install 

permanent geoelectric observatories in the United States.”117

87. Resilient Societies supports requiring the installation of GIC monitoring devices 

and magnetometers, noting that GIC monitors are commercially available and cost as 

 

116 BPA Comments at 4.

117 AEP March 29, 2016 Supplemental Comments at 1.
Docket No. RM15-11-000 - 57 -

little as $10,000 to $15,000 each. Emprimus supports developing criteria that inform the 

need for and location of monitoring devices.

Commission Determination

88. We conclude that additional collection and disclosure of GIC monitoring and 

magnetometer data is necessary to improve our collective understanding of the threats 

posed by GMD events. The Commission therefore adopts the NOPR proposal in relevant 

part and directs NERC to develop revisions to Reliability Standard TPL-007-1 to require 

responsible entities to collect GIC monitoring and magnetometer data as necessary to 

enable model validation and situational awareness, including from any devices that must 

be added to meet this need. The NERC standard drafting team should address the 

criteria for collecting GIC monitoring and magnetometer data discussed below and 

provide registered entities with sufficient guidance in terms of defining the data that must 

be collected, and NERC should propose in the GMD research work plan how it will 

determine and report on the degree to which industry is following that guidance. 

89. In addition, the Commission directs NERC, pursuant to Section 1600 of the NERC 

Rules of Procedure, to collect GIC monitoring and magnetometer data from registered 

entities for the period beginning May 2013, including both data existing as of the date of 

this order and new data going forward, and to make that information available.

118

 We 

also provide guidance that, as a general matter, the Commission does not believe that 

 

118 The Commission’s directives to collect and make available GIC monitoring and 

magnetometer data do not apply to non-U.S. responsible entities or Alaska and Hawaii.
Docket No. RM15-11-000 - 58 -

GIC monitoring and magnetometer data should be treated as Confidential Information 

pursuant to the NERC Rules of Procedure. 

Collection of GIC and Magnetometer Data

90. In developing a requirement regarding the collection of magnetometer data, NERC 

should consider the following criteria discussed at the March 1, 2016 Technical 

Conference: (1) the data is sampled at a cadence of at least 10-seconds or faster; (2) the 

data comes from magnetometers that are physically close to GIC monitors; (3) the data 

comes from magnetometers that are not near sources of magnetic interference (e.g., roads 

and local distribution networks); and (4) data is collected from magnetometers spread 

across wide latitudes and longitudes and from diverse physiographic regions.119

91. Each responsible entity that is a transmission owner should be required to collect 

necessary GIC monitoring data. However, a transmission owner should be able to apply 

for an exemption from the GIC monitoring data collection requirement if it demonstrates

that no or little value would be added to planning and operations. In developing a 

requirement regarding the collection of GIC monitoring data, NERC should consider the 

following criteria discussed at the March 1, 2016 Technical Conference: (1) the GIC data 

is from areas found to have high GIC based on system studies; (2) the GIC data comes 

from sensitive installations and key parts of the transmission grid; and (3) the data comes 

from GIC monitors that are not situated near transportation systems using direct current 

 

119 Slide Presentation of Luis Marti (Third Panel), March 1, 2016 Technical 

Conference at 3, 9.
Docket No. RM15-11-000 - 59 -

(e.g., subways or light rail).120 GIC monitoring and magnetometer locations should also 

be revisited after GIC system models are run with improved ground conductivity models. 

NERC may also propose to incorporate the GIC monitoring and magnetometer data 

collection requirements in a different Reliability Standard (e.g., real-time reliability 

monitoring and analysis capabilities as part of the TOP Reliability Standards).

92. Our determination differs from the NOPR proposal in that the NOPR proposed to 

require the installation of GIC monitors and magnetometers. The comments raised

legitimate concerns about incorporating such a requirement in Reliability Standard TPL007-1 because of the complexities of siting and operating monitoring devices to achieve 

the maximum benefits for model validation and situational awareness. In particular, 

responsible entities may not have the technical capacity to properly install and operate 

magnetometers, given complicating issues such as man-made interference, calibration, 

and data interpretation. Accordingly, the Commission determines that requiring 

responsible entities to collect necessary GIC monitoring and magnetometer data, rather 

than install GIC monitors and magnetometers, affords greater flexibility while obtaining 

significant benefits. For example, responsible entities could collaborate with universities 

and government entities that operate magnetometers to collect necessary magnetometer 

data, or responsible entities could choose to install GIC monitors or magnetometers to 

comply with the data collection requirement. While the Commission’s primary concern

 

120 Id. at 8.
Docket No. RM15-11-000 - 60 -

is the quality of the data collected, we do not establish a requirement for either approach 

or promote a particular device for collecting the required data. We also find that cost 

recovery for prudent costs associated with or incurred to comply with Reliability 

Standard TPL-007-1 and future revisions to the Reliability Standard, including for the 

purchase and installation of monitoring devices, will be available to registered entities.121

Data Availability

93. We also direct NERC, pursuant to Sections 1500 and 1600 of the NERC Rules of 

Procedure, to collect and make GIC monitoring and magnetometer data available.

122

 We 

determine that the dissemination of GIC monitoring and magnetometer data will facilitate 

a greater understanding of GMD events that, over time, will improve Reliability Standard 

TPL-007-1. The record in this proceeding supports the conclusion that access to GIC 

monitoring and magnetometer data will help facilitate GMD research, for example, by 

helping to validate GMD models.123 To facilitate the prompt dissemination of GIC 

monitoring and magnetometer data, we address whether GIC monitoring or 

 

121 NOPR, 151 FERC ¶ 61,134 at P 49 n.60.

122 If GIC monitoring and magnetometer data is already publicly available (e.g., 

from a government entity or university), NERC need not duplicate those efforts.

123 See, e.g., March 1, 2016 Technical Conference Tr. 58:22-59:13 (Love); 128:5-

129:2 (Overbye); ATC Comments at 6-7(“as more measuring devices (including 

magnetometers and GIC monitors) continue to propagate, the body of field data on 

magnetic fields and the resultant GICs will continue to increase the understanding of this 

phenomena and result in better models that more closely match real world conditions ... 

[a]bsent this field data, it is difficult to build accurate models that can be used to plan and 

operate the transmission system”).
Docket No. RM15-11-000 - 61 -

magnetometer data should qualify as Confidential Information under the NERC Rules of 

Procedure.124

94. Based on the record in this proceeding, we believe that GIC and magnetometer 

data typically should not be designated as Confidential Information under the NERC 

Rules of Procedure. We are not persuaded that the dissemination of GIC monitoring or 

magnetometer data poses a security risk or that the data otherwise qualify as Confidential 

Information. CEA and Hydro One have objected, without elaboration, to making data

available without the use of non-disclosure agreements.125 At the March 1, 2016 

Technical Conference, panelists were questioned on the topic yet could not identify a 

security-based or other credible reason for not making such information available to 

requesters. In comments submitted after the March 1, 2016 Technical Conference, the 

Trade Associations explained that “GIC measurements, while not as sensitive as 

transmission planning studies, should also be protected ... [because a] potentially 

malicious actor could conceivably combine GIC information with information from other 

sources to deduce the configuration and operating conditions of the grid or some portion 

 

124 Providers of GIC and magnetometer data may request that NERC treat their 

GIC monitoring and magnetometer data as “Confidential Information,” as that term is 

defined in Section 1500 of the NERC Rules of Procedure. Under the NERC Rules of 

Procedure, disclosure of Confidential Information by NERC to a requester requires a 

formal request, notice and opportunity for comment, and an executed non-disclosure 

agreement for requesters not seeking public disclosure of the information. NERC Rules 

of Procedure, Section 1503 (Requests for Information) (effective Nov. 4, 2015). 

125 CEA Comments at 15; Hydro One Comments at 2.
Docket No. RM15-11-000 - 62 -

of it.”126 The Trade Associations’ comments, however, do not substantiate the assertion

that the release of GIC monitoring (or magnetometer data) alone poses any risk to the 

Bulk-Power System. The Trade Associations’ comment is also vague by not identifying 

what “information from other sources” could be combined with GIC monitoring “to 

deduce the configuration and operating conditions of the grid or some portion of it.”

95. In conclusion, given both the lack of substantiated concerns regarding the 

disclosure of GIC and magnetometer data, and the compelling demonstration that access 

to these data will support ongoing research and analysis of GMD threats, the Commission 

expects NERC to make GIC and magnetometer data available. Notwithstanding our 

findings here, to the extent any entity seeks confidential treatment of the data it provides 

to NERC, the burden rests on that entity to justify the confidential treatment.127

Exceptions are possible if the providing entity obtains from NERC, at the time it submits 

data to NERC, a determination that GIC or magnetometer data qualify as Confidential 

Information.128 Entities denied access to GIC and magnetometer data by NERC or 

 

126 Trade Associations March 7, 2016 Supplemental Comments at 5. 

127 See NERC Rules of Procedure, Section 1502.1. To address any substantiated 

concerns regarding the need for confidentiality of an entity’s GIC or magnetometer data, 

NERC could develop a policy for disseminating such data only after an appropriate time 

interval (e.g., six months).

128 We understand that NERC typically does not determine whether information 

submitted to it under a claim of confidentiality is Confidential Information when 

receiving such information. See North American Electric Reliability Corp., 119 FERC 

¶ 61,060, at PP 195-196 (2007). We expect that, when a submitter seeks a determination 

(continued...)
Docket No. RM15-11-000 - 63 -

providers denied Confidential Information treatment of GIC and magnetometer data may

appeal NERC’s decision to the Commission. 

E. Corrective Action Plan Deadlines

NERC Petition

96. Reliability Standard TPL-007-1, Requirement R7 provides that:

Each responsible entity, as determined in Requirement R1, that concludes, 

through the GMD Vulnerability Assessment conducted in Requirement R4, 

that their System does not meet the performance requirements of Table 1 

shall develop a Corrective Action Plan addressing how the performance 

requirements will be met ....

NERC explains that the NERC Glossary defines corrective action plan to mean, “A list of 

actions and an associated timetable for implementation to remedy a specific problem.”

129

 

Requirement R7.3 states that the corrective action plan shall be provided within “90 

calendar days of completion to the responsible entity’s Reliability Coordinator, adjacent 

Planning Coordinator(s), adjacent Transmission Planner(s), functional entities referenced 

in the Corrective Action Plan, and any functional entity that submits a written request and 

has a reliability-related need.”

NOPR

97. The NOPR proposed to direct NERC to modify Reliability Standard TPL-007-1 to 

require corrective action plans to be developed within one year of the completion of the 

 

by NERC of a claim that GIC or magnetometer data qualify as Confidential Information, 

NERC will decide promptly.

129 NERC Petition at 31.
Docket No. RM15-11-000 - 64 -

GMD Vulnerability Assessment. The NOPR also proposed to direct NERC to modify 

Reliability Standard TPL-007-1 to require a deadline for non-equipment mitigation 

measures that is two years following development of the corrective action plan and a 

deadline for mitigation measures involving equipment installation that is four years 

following development of the corrective action plan. Recognizing that there is little 

experience with installing equipment for GMD mitigation, the NOPR stated that the 

Commission is open to proposals that may differ from its proposal, particularly from any 

entities with experience in this area. The NOPR also sought comment on appropriate 

alternative deadlines and whether there should be a mechanism that would allow NERC 

to consider, on a case-by-case basis, requests for extensions of required deadlines.

Comments

98. NERC states that it does not oppose a one-year deadline for completing the 

development of corrective action plans.130 However, NERC contends that imposing 

deadlines on the completion of mitigation actions would be problematic because of the 

uncertainties regarding the amount of time needed to install necessary equipment. NERC 

maintains that deadlines that are too short may cause entities to take mitigation steps that, 

 

130 NERC contends that a deadline is unnecessary because “NERC expects that 

applicable entities would determine necessary corrective actions as part of their GMD 

Vulnerability Assessments for the initial assessment [due 60 months after a final rule in 

this proceeding goes into effect] as well as subsequent assessments [due every 60 months 

thereafter].” NERC Comments at 28.
Docket No. RM15-11-000 - 65 -

while quicker, would not be as effective as mitigations that take more time to complete. 

NERC supports allowing extensions if the Commission adopts the NOPR proposal.

99. AEP states that, even if possible, a one-year deadline for developing corrective 

action plans is too aggressive and would encourage narrow thinking (i.e., registered 

entities would address GMD mitigation rather than pursue system improvements 

generally that would also address GMD mitigation). AEP, instead, proposes a two-year 

deadline. AEP does not support a Commission-imposed deadline for completing 

mitigation actions, although it supports requiring a time-table in the corrective action 

plan. AEP notes that the Commission did not impose a specific deadline for completion 

of corrective actions in Reliability Standard TPL-001-4 (Transmission System Planning 

Performance). CEA does not support a deadline for the development of corrective action 

plans because it is already part of the GMD Vulnerability Assessment process. Like 

AEP, CEA does not support specific deadlines for the completion of mitigation actions 

and instead supports including time-tables in the corrective action plan. CEA also 

contends that an extension process would be impracticable.

100. Trade Associations, BPA and Tri-State support the imposition of corrective action 

plan deadlines as long as entities can request extensions. Gaunt supports the corrective 

action plan deadlines proposed in the NOPR. Emprimus supports the imposition of 

deadlines but contends that non-equipment mitigation actions should be completed in 

6 months and that there should be a rolling four-year period for equipment mitigation 

(i.e., after each year, 25 percent of the total mitigation actions should be completed).
Docket No. RM15-11-000 - 66 -

Commission Determination

101. The Commission directs NERC to modify Reliability Standard TPL-007-1 to 

include a deadline of one year from the completion of the GMD Vulnerability 

Assessments to complete the development of corrective action plans. NERC’s statement 

that it “expects” corrective action plans to be completed at the same time as GMD 

Vulnerability Assessments concedes the point made in the NOPR that Reliability 

Standard TPL-007-1 currently lacks a clear deadline for the development of corrective 

action plans. 

102. The Commission also directs NERC to modify Reliability Standard TPL-007-1 to

include a two-year deadline after the development of the corrective action plan to 

complete the implementation of non-hardware mitigation and four-year deadline to 

complete hardware mitigation. The comments provide contrasting views on the 

practicality of imposing mitigation deadlines, with NERC and some industry commenters 

arguing that such deadlines are not warranted while the Trade Associations and other 

industry commenters support their imposition. Most of these comments, however,

support an extension process if the Commission determines that deadlines are necessary. 

The Commission agrees that NERC should consider extensions of time on a case-by-case 

basis. The Commission directs NERC to submit these revisions within 18 months of the 

effective date of this Final Rule.

103. Following adoption of the mitigation deadlines required in this final rule, 

Reliability Standard TPL-007-1 will establish a recurring five-year schedule for the 

identification and mitigation of potential GMD risks on the grid, as follows: (1) the 
Docket No. RM15-11-000 - 67 -

development of corrective action plans must be completed within one year of a GMD 

Vulnerability Assessment; (2) non-hardware mitigation must be completed within two 

years following development of corrective action plans; and (3) hardware mitigation 

must be completed within four years following development of corrective action plans.

104. As discussed elsewhere in this final rule, the Commission recognizes and expects 

that our collective understanding of the science regarding GMD threats will improve over 

time as additional research and analysis is conducted. We believe that the recurring fiveyear cycle will provide, on a going-forward basis, the opportunity to update Reliability 

Standard TPL-007-1to reflect new or improved scientific understanding of GMD events. 

F. Minimization of Load Loss and Curtailment

NERC Petition

105. Reliability Standard TPL-007-1, Requirement R4 states that each responsible 

entity “shall complete a GMD Vulnerability Assessment of the Near-Term Transmission 

Planning Horizon once every 60 calendar months.” Requirement R4.2 further states that 

the “study or studies shall be conducted based on the benchmark GMD event described in 

Attachment 1 to determine whether the System meets the performance requirements in 

Table 1.” 

106. NERC maintains that Table 1 sets forth requirements for system steady state 

performance. NERC explains that Requirement R4 and Table 1 “address assessments of 

the effects of GICs on other Bulk‐Power System equipment, system operations, and 
Docket No. RM15-11-000 - 68 -

system stability, including the loss of devices due to GIC impacts.”131 Table 1 provides, 

in relevant part, that load loss and/or curtailment are permissible elements of the steady 

state:

Load loss as a result of manual or automatic Load shedding (e.g. UVLS) 

and/or curtailment of Firm Transmission Service may be used to meet BES 

performance requirements during studied GMD conditions. The likelihood 

and magnitude of Load loss or curtailment of Firm Transmission Service 

should be minimized.

NOPR

107. The NOPR sought comment on the provision in Table 1 that “Load loss or 

curtailment of Firm Transmission Service should be minimized.” The NOPR stated that 

because the term “minimized” does not represent an objective value, the provision is

potentially subject to interpretation and assertions that the term is vague and may not be

enforceable. The NOPR also explained that the modifier “should” might indicate that 

minimization of load loss or curtailment is only an expectation or a guideline rather than 

a requirement. The NOPR sought comment on how the provision in Table 1 regarding 

load loss and curtailment will be enforced, including: (1) whether, by using the term 

“should,” Table 1 requires minimization of load loss or curtailment; or both and (2) what 

constitutes “minimization” and how it will be assessed.

 

131 NERC Petition at 39.
Docket No. RM15-11-000 - 69 -

Comments

108. NERC states the language in Table 1 is modeled on Reliability Standard TPL001-4, which provides in part that “an objective of the planning process should be to 

minimize the likelihood and magnitude of interruption of Firm transmission Service 

following Contingency events.” NERC explains that Reliability Standard TPL-007-1 

“does not include additional load loss performance criteria used in normal contingency 

planning because such criteria may not be applicable to GMD Vulnerability Assessment 

of the impact from a 1-in-100 year GMD event.”132 However, NERC points out that the 

enforcement of Requirement R4 “would include an evaluation of whether the system 

meets the Steady State performance requirements of Table 1 which are aimed at 

protecting against instability, controlled separation, and Cascading.”133 NERC further 

states that “minimized” in the context of Reliability Standard TPL-007-1 means that 

“planned Load loss or curtailments are not to exceed amounts necessary to prevent 

voltage collapse.”134

109. The Trade Associations agree with the NOPR that the lack of objective criteria 

could create compliance and enforcement challenges and could limit an operator’s 

actions in real-time. The Trade Associations state that the Commission “should consider 

 

132 NERC Comments at 29.

133 Id.

134 Id.
Docket No. RM15-11-000 - 70 -

whether such language in mandatory requirements invites the unintended consequences 

of raising reliability risks, especially during real-time emergency conditions ... [but] [i]n 

the interim, the Trade Associations envision that NERC will consider further discussions 

with stakeholders on the issue prior to TPL-007 implementation.”135

Commission Determination

110. The Commission accepts the explanation in NERC’s comments of what is meant 

by the term “minimized” in Table 1. 

G. Violation Risk Factors and Violation Severity Levels

111. Each requirement of Reliability Standard TPL-007-1 includes one violation risk 

factor and has an associated set of at least one violation severity level. NERC states that 

the ranges of penalties for violations will be based on the sanctions table and supporting 

penalty determination process described in the Commission approved NERC Sanction 

Guidelines. The NOPR proposed to approve the violation risk factors and violation 

severity levels submitted by NERC, for the requirements in Reliability Standard TPL007-1, consistent with the Commission’s established guidelines.136

 The Commission did 

not receive any comments regarding this aspect of the NOPR. Accordingly, the 

Commission approves the violation risk factors and violation severity levels for the 

requirements in Reliability Standard TPL-007-1.

 

135 Trade Associations Comments at 28.

136 North American Electric Reliability Corp., 135 FERC ¶ 61,166 (2011).
Docket No. RM15-11-000 - 71 -

H. Implementation Plan and Effective Dates

NERC Petition

112. NERC proposes a phased, five-year implementation period.137 NERC maintains 

that the proposed implementation period is necessary: (1) to allow time for entities to 

develop the required models; (2) for proper sequencing of assessments because thermal 

impact assessments are dependent on GIC flow calculations that are determined by the 

responsible planning entity; and (3) to give time for development of viable corrective 

action plans, which may require applicable entities to “develop, perform, and/or validate 

new or modified studies, assessments, procedures ... [and because] [s]ome mitigation 

measures may have significant budget, siting, or construction planning requirements.”138

113. The proposed implementation plan states that Requirement R1 shall become 

effective on the first day of the first calendar quarter that is six months after Commission 

approval. For Requirement R2, NERC proposes that the requirement shall become 

effective on the first day of the first calendar quarter that is 18 months after Commission 

approval. NERC proposes that Requirement R5 shall become effective on the first day of 

the first calendar quarter that is 24 months after Commission approval. NERC proposes 

that Requirement R6 shall become effective on the first day of the first calendar quarter 

that is 48 months after Commission approval. And for Requirement R3, Requirement 

 

137 NERC Petition, Ex. B (Implementation Plan for TPL-007-1).

138 Id. at 2.
Docket No. RM15-11-000 - 72 -

R4, and Requirement R7, NERC proposes that the requirements shall become effective 

on the first day of the first calendar quarter that is 60 months after Commission approval. 

NOPR

114. The NOPR proposed to approve the implementation plan and effective dates 

submitted by NERC. However, given the serial nature of the requirements in Reliability 

Standard TPL-007-1, the Commission expressed concern about the duration of the 

timeline associated with any mitigation stemming from a corrective action plan and 

sought comment from NERC and other interested entities as to whether the length of the 

implementation plan, particularly with respect to Requirements R4, R5, R6, and R7, 

could be reasonably shortened.

Comments

115. NERC does not support shortening the implementation period. NERC maintains 

that the proposed implementation period is “appropriate and commensurate with the 

requirements of the proposed standard” and is based on “industry ... projections on the 

time required for obtaining validated tools, models and data necessary for conducting 

GMD Vulnerability Assessments through the standard development process.”139 NERC 

notes that the standard drafting team initially proposed a four-year implementation plan, 

but received substantial comments expressing concern with only having four years.

 

139 NERC Comments at 30.
Docket No. RM15-11-000 - 73 -

116. The Trade Associations, BPA, CEA, Joint ISOs/RTOs and Tri-State support the 

proposed implementation plan for largely the same reasons as NERC.

117. Gaunt proposes a shorter implementation period wherein the initial GMD 

Vulnerability Assessment would be performed 48 months following the effective date 

of a final rule in this proceeding, as opposed to the proposed implementation plan’s 

60 months. Subsequent GMD Vulnerability Assessments would be performed every 

48 months thereafter. Briggs states that a “3 or 4 year timeline would likely provide 

industry with enough time to implement corrective measures and should be 

considered.”140

Commission Determination

118. The Commission approves the implementation plan submitted by NERC. When 

registered entities begin complying with Reliability Standard TPL-007-1, it will likely be 

the first time that many registered entities will have planned for a GMD event, beyond 

developing the GMD operational procedures required by Reliability Standard EOP-010-

1. Registered entities will gain the capacity to conduct GMD Vulnerability Assessments 

over the course of the five-year implementation plan by complying with, at phased 

intervals, the foundational requirements in Reliability Standard TPL-007-1 (i.e., 

establishing responsibilities for planning and developing models and performance 

criteria). In addition, as discussed above, NERC’s implementation plan affords sufficient 

 

140 Briggs Comments at 7.
Docket No. RM15-11-000 - 74 -

time for NERC to submit and for the Commission to consider the directed revisions to 

Reliability Standard TPL-007-1 before the completion of the first GMD Vulnerability 

Assessment. As such, the five-year implementation plan will allow for the incorporation 

of the revised Reliability Standard in the first round of GMD Vulnerability Assessments. 

I. Other Issues

119. Several commenters indicated that the Commission should address the threats 

posed by EMPs or otherwise raised the issue of EMPs.141 For example, Briggs states that 

the Commission should “initiate a process to improve the resilience of the U.S. electric 

grid to the threat of high altitude electromagnetic pulse (HEMP) attacks, which can be 

more severe than solar superstorms.”142 However, as the Commission stated in Order 

No. 779 in directing the development of GMD Reliability Standards and in Order 

No. 797 in approving the First Stage GMD Reliability Standards, EMPs are not within 

the scope of the GMD rulemaking proceedings.

143

120. Holdeman contends that the Commission “should modify the current preemption 

of States preventing them from having more stringent reliability standards for 

Commission regulated entities than Commission standards.”144 As the Commission 

 

141 See Briggs Comments at 7; EIS Comments at 3; JINSA Comments at 2.

142 Briggs Comments at 7.

143 Order No. 797, 147 FERC ¶ 61,209 at P 42 (citing Order No. 779, 143 FERC 

¶ 61,147 at P 14 n.20).

144 Holdeman Comments at 2.
Docket No. RM15-11-000 - 75 -

indicated in response to similar comments in Order No. 797, section 215(i)(3) of the FPA 

provides in relevant part that section 215 does not “preempt any authority of any State to 

take action to ensure the safety, adequacy, and reliability of electric service within that 

State, as long as such action is not inconsistent with any reliability standard.”145 

Moreover, Reliability Standard TPL-007-1 does not preclude users, owners, and 

operators of the Bulk-Power System from taking additional steps that are designed to 

mitigate the effects of GMD events, provided those additional steps are not inconsistent 

with the Commission-approved Reliability Standards.

121. Certain commenters opposed to Reliability Standard TPL-007-1 contend that its 

approval could absolve industry of any legal liability should a GMD event cause a 

disruption to the Bulk-Power System. For example, Resilient Societies “ask[s] the 

Commission to clarify its expectation that the FERC jurisdictional entities will be held to 

account, and be subject to liability in the event of gross negligence or willful misconduct 

in planning for and mitigating solar geomagnetic storms.”146 Resilient Societies also 

contends that the Commission does not have the legal authority “to grant immunity from 

liability by setting reliability standards.”147 

 

145 Order No. 797, 147 FERC ¶ 61,209 at P 44 (citing 16 U.S.C. 824o(i)(3)).

146 Resilient Societies Comments at 62; see also CSP Comments at 1 (“It would be 

far better for FERC to remand Standard TPL-007-1 in its entirety than to approve a 

reliability standard that would grant liability protection to utilities while blocking the 

electric grid protection for the public that a 21st century society requires.”).

147 Resilient Societies Comments at 62.
Docket No. RM15-11-000 - 76 -

122. The Commission has never stated in the GMD Reliability Standard rulemakings 

that compliance with Commission-approved Reliability Standards absolves registered 

entities from legal liability generally, to the extent legal liability exists, should a

disruption occur on the Bulk-Power System due to a GMD event. Resilient Societies’ 

comment appears to misconstrue language in Order No. 779 in which the Commission 

stated, when directing the development of the Second Stage GMD Reliability Standards, 

that the “Second Stage GMD Reliability Standard should not impose ‘strict liability’ on 

responsible entities for failure to ensure the reliability operation of the Bulk-Power 

System in the face of a GMD event of unforeseen severity.”148 The Commission’s 

statement merely recognized that the Second Stage GMD Reliability Standard should 

require registered entities to plan against a defined benchmark GMD event, for the 

purpose of complying with the proposed Reliability Standard, rather than any GMD event 

generally (i.e., a GMD event that exceeded the severity of the benchmark GMD event). 

The Commission did not suggest, nor could it suggest, that compliance with a Reliability 

Standard would absolve registered entities from general legal liability, if any, arising 

from a disruption to the Bulk-Power System. The only liability the Commission was 

referring to in Order No. 779 was the potential for penalties or remediation under 

section 215 of the FPA for failure to comply with a Commission-approved Reliability 

Standard. 

 

148 Order No. 779, 143 FERC ¶ 61,147 at P 84.
Docket No. RM15-11-000 - 77 -

123. Kappenman, Resilient Societies and Bardin filed comments that addressed the 

NERC “Level 2” Appeal Panel decision.149 As a threshold issue, we agree with the 

Appeal Panel that the issues raised by the appellants in that proceeding are not 

procedural; instead they address the substantive provisions of Reliability Standard TPL007-1. Section 8 (Process for Appealing an Action or Inaction) of the NERC Standards 

Process Manual states:

Any entity that has directly and materially affected interests and that has 

been or will be adversely affected by any procedural action or inaction 

related to the development, approval, revision, reaffirmation, retirement or 

withdrawal of a Reliability Standard, definition, Variance, associated 

implementation plan, or Interpretation shall have the right to appeal. This 

appeals process applies only to the NERC Reliability Standards processes 

as defined in this manual, not to the technical content of the Reliability 

Standards action.

The appellants, who have the burden of proof under the NERC Rules of Procedure, have 

not shown that NERC or the standard drafting team failed to comply with any procedural 

requirements set forth in the NERC Rules of Procedure.150 Instead, it would appear that 

the appeal constitutes a collateral attack on the substantive provisions of Reliability 

Standard TPL-007-1. As the appellants’ substantive concerns with Reliability Standard 

TPL-007-1 have been addressed in this Final Rule, issues surrounding the NERC 

“Level 2” Appeal Panel decision are, in any case, moot.

 

149 NERC August 17, 2015 Filing at Appendix 1 (Decision of Level 2 Appeal 

Panel SPM Section 8 Appeal the Foundation For Resilient Societies, Inc. TPL-007-1).

150 NERC Rules of Procedure, Appendix 3A (Standard Processes Manual), 

Section 8 (Process for Appealing an Action or Inaction) (effective June 26, 2013).
Docket No. RM15-11-000 - 78 -

III. Information Collection Statement

124. The collection of information contained in this final rule is subject to review by 

the Office of Management and Budget (OMB) regulations under section 3507(d) of the 

Paperwork Reduction Act of 1995 (PRA).151 OMB’s regulations require approval of 

certain informational collection requirements imposed by agency rules.152

125. Upon approval of a collection(s) of information, OMB will assign an OMB control 

number and an expiration date. Respondents subject to the filing requirements of a rule 

will not be penalized for failing to respond to these collections of information unless the 

collections of information display a valid OMB control number. 

126. The Commission solicited comments on the need for this information, whether the 

information will have practical utility, the accuracy of the burden estimates, ways to 

enhance the quality, utility, and clarity of the information to be collected or retained, and 

any suggested methods for minimizing respondents’ burden, including the use of 

automated information techniques. The Commission asked that any revised burden or 

cost estimates submitted by commenters be supported by sufficient detail to understand 

how the estimates are generated. The Commission received comments on specific 

requirements in Reliability Standard TPL-007-1, which we address in this Final Rule. 

However, the Commission did not receive any comments on our reporting burden 

 

151 44 U.S.C. 3507(d).

152 5 CFR 1320.11.
Docket No. RM15-11-000 - 79 -

estimates or on the need for and the purpose of the information collection 

requirements.153

Public Reporting Burden: The Commission approves Reliability Standard TPL-007-1 

and the associated implementation plan, violation severity levels, and violation risk 

factors, as discussed above. Reliability Standard TPL-007-1 will impose new 

requirements for transmission planners, planning coordinators, transmission owners, and 

generator owners. Reliability Standard TPL-007-1, Requirement R1 requires planning 

coordinators, in conjunction with the applicable transmission planner, to identify the 

responsibilities of the planning coordinator and transmission planner in the planning 

coordinator’s planning area for maintaining models and performing the study or studies 

needed to complete GMD Vulnerability Assessments. Requirements R2, R3, R4, R5, and 

R7 refer to the “responsible entity, as determined by Requirement R1,” when identifying 

which applicable planning coordinators or transmission planners are responsible for 

maintaining models and performing the necessary study or studies. Requirement R2 

requires that the responsible entities maintain models for performing the studies needed 

to complete GMD Vulnerability Assessments, as required in Requirement R4. 

Requirement R3 requires responsible entities to have criteria for acceptable system steady 

 

153 While noting the uncertainties surrounding the potential costs associated with 

implementation of Reliability Standard TPL-007-1 and the potential costs that could arise 

from a revised Reliability Standard, the Trade Associations stated that they “have no 

specific comments regarding the OMB cost estimate in the NOPR.” Trade Associations 

Comments at 9. 
Docket No. RM15-11-000 - 80 -

state voltage performance during a benchmark GMD event. Requirement R4 requires 

responsible entities to complete a GMD Vulnerability Assessment of the near-term 

transmission planning horizon once every 60 calendar months. Requirement R5 requires 

responsible entities to provide GIC flow information to transmission owners and 

generator owners that own an applicable bulk electric system power transformer in the 

planning area. This information is necessary for applicable transmission owners and 

generator owners to conduct the thermal impact assessments required by proposed 

Requirement R6. Requirement R6 requires applicable transmission owners and generator 

owners to conduct thermal impact assessments where the maximum effective GIC value 

provided in proposed Requirement R5, Part 5.1 is 75 A/phase or greater. Requirement 

R7 requires responsible entities to develop a corrective action plan when its GMD 

Vulnerability Assessment indicates that its system does not meet the performance 

requirements of Table 1 – Steady State Planning Events. The corrective action plan must 

address how the performance requirements will be met, must list the specific deficiencies 

and associated actions that are necessary to achieve performance, and must set forth a 

timetable for completion. The Commission estimates the annual reporting burden and 

cost as follows: 
Docket No. RM15-11-000 - 81 -

FERC-725N, as modified by the Final Rule in Docket No. RM15-11-000 (TPL-007-1 

Reliability Standard for Transmission System Planned Performance for 

Geomagnetic Disturbance Events)154

Number 

of 

Responde

nts

(1)

Annual 

Number 

of 

Response

s per 

Respond

ent

(2)

Total 

Number 

of 

Response

s 

(1)*(2)=(

3)

Average 

Burden 

Hours & 

Cost Per 

Response

155

(4)

Total 

Annual 

Burden 

Hours & 

Total 

Annual 

Cost

(3)*(4)=(5)

Cost 

per 

Respon

dent

($)

(5)÷(1)

(One-time) 

Requirement 1 

121 (PC & 

TP)

1 121 Eng. 5 

hrs. 

($331.75); 

RK 4 hrs. 

($149.80) 

1,089 hrs. 

(605 Eng., 

484 RK); 

$58,267.55 

($40,141.7

5 Eng., 

$18,125.80 

RK) 

$481.55

(On-going) 

Requirement 1

121 (PC & 

TP)

1 121 Eng. 3 

hrs. 

($199.05); 

RK 2 hrs. 

($74.90)

605 hrs. 

(363 Eng., 

242 RK); 

$33,147.95 

($24,085.0

5 Eng., 

$9,062.90 

RK) 

$273.95

 

154 Eng.=engineer; RK =recordkeeping (record clerk); PC=planning coordinator; 

TP=transmission planner; TO=transmission owner; and GO=generator owner.

155 The estimates for cost per response are derived using the following formula: 

Burden Hours per Response * $/hour = Cost per Response. The $66.35/hour figure for 

an engineer and the $37.45/hour figure for a record clerk are based on data on the average 

salary plus benefits from the Bureau of Labor Statistics obtainable at 

http://www.bls.gov/oes/current/naics3_221000.htm and 

http://www.bls.gov/news.release/ecec.nr0.htm. 
Docket No. RM15

-11-000 - 82 -

(One-time) 

Requirement 2

121 (PC & 

TP)

1 121 Eng. 22 

hrs. 

($1,459.7

0); RK 18 

hrs. 

($674.10)

4840 hrs. 

(2,662 

Eng., 2,178 

RK); 

$258,189.8

0 

($176,623.

70 Eng., 

$81,566.10 

RK)

$2,133.

80

(On-going) 

Requirement 2

121 (PC & 

TP)

1 121 Eng. 5 

hrs. 

($331.75); 

RK 3 hrs. 

($112.35) 

968 hrs. 

(605 Eng., 

363 RK); 

$53,736.10 

($40,141.7

5 Eng., 

$13,594.35 

RK) 

$444.10

(One-time) 

Requirement 3

121 (PC & 

TP)

1 121 Eng. 5 

hrs. 

($331.75); 

RK 3 hrs. 

($112.35)

968 hrs. 

(605 Eng., 

363 RK); 

$53,736.10 

($40,141.7

5 Eng., 

$13,594.35 

RK) 

$444.10

(On-going)

Requirement 3

121 (PC & 

TP)

1 121 Eng. 1 

hrs. 

($66.35);

RK 1 hrs. 

($37.45) 

242 hrs. 

(121 Eng., 

121 RK); 

$12,559.80 

($8,028.35 

Eng., 

$4,531.45 

RK)

$103.80
Docket No. RM15

-11-000 - 83 -

(On-going) 

Requirement 4

121 (PC & 

TP)

1 121 Eng. 27 

hrs. 

($1,791.4

5); RK 21 

hrs. 

($786.45) 

5,808 hrs. 

(3,267 

Eng., 2,541 

RK); 

$311,919.8

5 

($216,765.

45 Eng., 

$95,154.40 

RK)

$2,277.

85

(On-going) 

Requirement 5

121 (PC & 

TP)

1 121 Eng. 9 

hrs. 

($597.15); 

RK 7 hrs. 

($262.15) 

1936 hrs. 

(1,089 

Eng., 847 

RK); 

$103,975.3

0 

($72,255.1

5 Eng., 

$31,720.15 

RK) 

$859.30

(One-time) 

Requirement 6 

881 (TO 

& GO)

1 881 Eng. 22 

hrs. 

($1,459.7

0); RK 18 

hrs. 

($674.19) 

35,240 hrs. 

(19,382 

Eng.,

15,858 

RK); 

$1,879,957.

09 

($1,285,99

5.70 Eng., 

$593,961.3

9 RK) 

$2,133.

89

(On-going) 

Requirement 6 

881 (TO 

& GO)

1 881 Eng. 2 

hrs. 

($132.70); 

RK 2 hrs. 

($74.90) 

3,524 hrs. 

(1,762 

Eng., 1762 

RK); 

$182,895.6

0 

($116,908.

70 Eng., 

$65,986.90 

RK)

$207.60
Docket No. RM15-11-000 - 84 -

(On-going) 

Requirement 7

121 (PC & 

TP)

1 121 Eng. 11 

hrs. 

($729.85); 

RK 9 hrs. 

($337.05)

2,420 hrs. 

(1,331 

Eng., 1,089 

RK); 

$129,094.9

0 

($88,311.8

5 Eng., 

$40,783.05 

RK)

$1,066.

90

TOTAL 2851 57,640156

hrs. 

(31,792 

Eng., 

25,848 

RK); 

$3,077,480.

04 

($2,109,39

9.20 Eng., 

$968,080.8

4 RK) 

Title: FERC-725N, Mandatory Reliability Standards: TPL Reliability Standards.

Action: Approved Additional Requirements.

OMB Control No: 1902-0264.

Respondents: Business or other for-profit and not-for-profit institutions.

Frequency of Responses: One time and on-going. 

Necessity of the Information: The Commission has reviewed the requirements of

Reliability Standard TPL-007-1 and has made a determination that the requirements of 

 

156 Of the 57,640 total burden hours, 42,137 hours are one-time burden hours, and 

15,503 hours are on-going annual burden hours.
Docket No. RM15-11-000 - 85 -

this Reliability Standard are necessary to implement section 215 of the FPA. 

Specifically, these requirements address the threat posed by GMD events to the BulkPower System and conform to the Commission’s directives regarding development of the 

Second Stage GMD Reliability Standards, as set forth in Order No. 779. 

Internal review: The Commission has assured itself, by means of its internal review, that 

there is specific, objective support for the burden estimates associated with the

information requirements.

127. Interested persons may obtain information on the reporting requirements by 

contacting the Federal Energy Regulatory Commission, Office of the Executive Director, 

888 First Street, NE, Washington, DC 20426 [Attention: Ellen Brown, e-mail: 

DataClearance@ferc.gov, phone: (202) 502-8663, fax: (202) 273-0873]. 

128. Comments concerning the information collections proposed in this notice of 

proposed rulemaking and the associated burden estimates, should be sent to the 

Commission in this docket and may also be sent to the Office of Management and 

Budget, Office of Information and Regulatory Affairs [Attention: Desk Officer for the 

Federal Energy Regulatory Commission]. For security reasons, comments should be sent 

by e-mail to OMB at the following e-mail address: oira_submission@omb.eop.gov. 

Please reference FERC-725N and OMB Control No. 1902-0264 in your submission.
Docket No. RM15-11-000 - 86 -

IV. Environmental Analysis

129. 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.157 The Commission has categorically excluded certain 

actions from this requirement as not having a significant effect on the human 

environment. Included in the exclusion are rules that are clarifying, corrective, or 

procedural or that do not substantially change the effect of the regulations being 

amended.158 The actions here fall within this categorical exclusion in the Commission’s 

regulations. 

V. Regulatory Flexibility Act

130. The Regulatory Flexibility Act of 1980 (RFA)159 generally requires a description 

and analysis of final rules that will have significant economic impact on a substantial 

number of small entities. The Small Business Administration’s (SBA) Office of Size 

Standards develops the numerical definition of a small business.160 The SBA revised its 

size standard for electric utilities (effective January 22, 2014) to a standard based on the 

 

157 Regulations Implementing the National Environmental Policy Act of 1969, 

Order No. 486, 52 FR 47897 (Dec. 17, 1987), FERC Stats. & Regs. Preambles 1986-

1990 ¶ 30,783 (1987).

158 18 CFR 380.4(a)(2)(ii).

159 5 U.S.C. 601-12.

160 13 CFR 121.101.
Docket No. RM15-11-000 - 87 -

number of employees, including affiliates (from a standard based on megawatt hours).161

Under SBA’s new size standards, planning coordinators, transmission planners, 

transmission owners, and generator owners are likely included in one of the following 

categories (with the associated size thresholds noted for each):162

 Hydroelectric power generation, at 500 employees 

 Fossil fuel electric power generation, at 750 employees

 Nuclear electric power generation, at 750 employees

 Other electric power generation (e.g., solar, wind, geothermal, biomass, and 

other), at 250 employees

 Electric bulk power transmission and control,163 at 500 employees

131. Based on these categories, the Commission will use a conservative threshold of 

750 employees for all entities.164 Applying this threshold, the Commission estimates that 

there are 440 small entities that function as planning coordinators, transmission planners, 

transmission owners, and/or generator owners. However, the Commission estimates that 

only a subset of such small entities will be subject to the approved Reliability Standard 

 

161 SBA Final Rule on “Small Business Size Standards: Utilities,” 78 FR 77,343 

(Dec. 23, 2013).

162 13 CFR 121.201, Sector 22, Utilities. 

163 This category covers transmission planners and planning coordinators.

164 By using the highest number threshold for all types of entities, our estimate 

conservatively treats more entities as “small entities.” 
Docket No. RM15-11-000 - 88 -

given the additional applicability criterion in the approved Reliability Standard (i.e., to be 

subject to the requirements of the approved Reliability Standard, the applicable entity 

must own or must have a planning area that contains a large power transformer with a 

high side, wye-grounded winding with terminal voltage greater than 200 kV).

132. Reliability Standard TPL-007- 1 enhances reliability by establishing 

requirements that require applicable entities to perform GMD Vulnerability Assessments 

and to mitigate identified vulnerabilities. The Commission estimates that each of the 

small entities to whom the approved Reliability Standard applies will incur one-time 

compliance costs of $5,193.34 and annual ongoing costs of $5,233.50. 

133. The Commission does not consider the estimated cost per small entity to impose a 

significant economic impact on a substantial number of small entities. Accordingly, the 

Commission certifies that the approved Reliability Standard will not have a significant

economic impact on a substantial number of small entities. 

VI. Document Availability

134. 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, N.E., Room 2A, 

Washington, DC 20426.

135. 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 
Docket No. RM15-11-000 - 89 -

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.

136. 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.

VII. Effective Date and Congressional Notification

137. These regulations are effective [INSERT DATE 60 days after publication 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.

By the Commission.

( S E A L )

Nathaniel J. Davis, Sr.,

Deputy Secretary.
Docket No. RM15-11-000 - 90 -

APPENDIX

Commenters

Initial Comments 

Abbreviation Commenter

AEP American Electric Power Service Corporation

APS Arizona Public Service Company

ATC American Transmission Company

Baker Greta Baker

Bardin David J. Bardin

BPA Bonneville Power Administration

Briggs Kevin Briggs

CEA Canadian Electricity Association

CSP Center for Security Policy

EIS Electric Infrastructure Security Council

Emprimus Emprimus LLC

Exelon Exelon Corporation

Gaunt Charles T. Gaunt

Holdeman Eric Holdeman 

Hydro One Hydro One Networks Inc.

ITC International Transmission Company

Lloyd’s Lloyd’s America, Inc.

JINSA Jewish Institute for National Security Affairs

Joint ISOs/RTOs ISO New England Inc., Midcontinent Independent 

Transmission System Operator, Inc., Independent Electricity 

System Operator, New York Independent System Operator, 

Inc., and PJM Interconnection, L.L.C.

Kappenman John G. Kappenman and Curtis Birnbach

Morris Eric S. Morris

NERC North American Electric Reliability Corporation

Resilient Societies Foundation for Resilient Societies

Roodman David Roodman

Trade Associations American Public Power Association, Edison Electric

Institute, Electricity Consumers Resource Council, Electric 

Power Supply Association, Large Public Power Council, 

National Rural Electric Cooperative Association

Tri-State Tri-State Generation and Transmission Association, Inc.

USGS United States Geological Survey
Docket No. RM15-11-000 - 91 -

Supplemental Comments

AEP American Electric Power Service Corporation

Bardin David J. Bardin

CSP Center for Security Policy

Gaunt Charles T. Gaunt

IEEE IEEE Power and Energy Society Transformers Committee

Kappenman John G. Kappenman and Curtis Birnbach

NERC North American Electric Reliability Corporation

Resilient Societies Foundation for Resilient Societies

Roodman David Roodman

Trade Associations American Public Power Association, Edison Electric

Institute, Electricity Consumers Resource Council, Electric 

Power Supply Association, Large Public Power Council, 

National Rural Electric Cooperative Association

USGS United States Geological Survey