3

- i CHAPTER 3. MARKET AND TECHNOLOG Y ASSESSMENT

TABLE OF CONTENTS

3.1 INTRODUCTION ............................................................................................... 3-1
3.2 DISTRIBUTION TRANSFO RMER DEFINITIONS ......................................... 3-1
3.3 EQUIPMENT CLASSES .................................................................................... 3-2
3.4 NATIONAL SHIPMENT ES TIMATE ............................................................... 3-4
3.5 MANUFACTURERS OF DISTRIBUTION TRANSFORME RS ...................... 3-8
3.5.1 Potential Small Business Impacts ........................................................................ 3-9
3.5.2 Distribution and Sales Channels .......................................................................... 3-9

3.6 TOTAL OWNING COST EVALUATION ....................................................... 3-10
3.6.1 National Electrical Manufacturers Association TP 1 Standard ......................... 3-12
3.6.2 National Electrical Manufacturers Association

– NEMA Premium Program ... 3-13
3.6.3 Energy Star Transformers .................................................................................. 3-14
3.6.4 Consortium for Energy Efficiency ..................................................................... 3-14
3.6.5 Federal Energy Management Program .............................................................. 3-15

3.6.6 National Grid ..................................................................................................... 3-15
3.6.7 Seattle City Light ............................................................................................... 3-15
3.7 RE GULATORY PROGRAMS ......................................................................... 3-15
3.7.1 U.S. National Energy Bill – Energy Policy Act of 2005 ................................... 3-16

3.7.2 Canadian Efficiency Standard ............................................................................ 3-16
3.7.3 Mexican Efficiency Standard ............................................................................. 3-20
3.8 TECHNOLOGY ASSESSMEN T ...................................................................... 3-24
3.8.1 Distribution Transformer Types ........................................................................ 3-24

3.8.2 Transformer Efficiency Levels .......................................................................... 3-25
3.8.3 Transformer Losses ............................................................................................ 3-26
3.8.4 Core Deactivation .............................................................................................. 3-28
3.8.5 Symmetric Core ................................................................................................. 3-29

LIST OF TABLES

Table 3.2.1 Normal Impedance Ranges for Liquid- Immersed Transformers

........... Error!
Bookmark not defined. Table 3.2.2 Normal Impeda nce Ranges for Dry

- Type Transformers

.... Error! Bookmark
not defined. Table 3.3.1 Distribution Transformer Equipment Classes .............................................. 3-3 Table 3.4.1 National Distribution Transformer Shipment Estimates for 2009 ............... 3-7
Table 3.7.1 National Electr ical Manufacturers Association TP 1 Efficiency Levels for Liquid- Immersed Distribution Transformers ............................................. 3-13
Table 3.7.2 National Elec trical Manufacturers Association TP 1 Efficiency Levels for Dry -Type Distribution Transformers ......................................................... 3-133

- ii Table 3.7.3 NEMA Premium Effici ency Levels for Low -Voltage, Dry- Type Distribution
Transformers .............................................................................................. 3-14 Table 3.8.1 Canadian Minimum Efficiency Standards for Dry- Type Transformers .... 3-20 Table 3.8.2 Characteristics of Regulated Distribution Transformers in Mexico .......... 3-21

Ta ble 3.8.3 Minimum Efficiency Levels for Transformers in Mexico ......................... 3-22
Table 3.8.4 Maximum Allowed Losses for Transformers in Mexico ........................... 3-23 Table 3.9.1 Options and Impacts of Increasing Transformer Efficiency ...................... 3-28

LIST OF FIGURES

Figure 3.4.1 Liquid-Immersed Unit Shipments, 2009 .................................................... 3-5 Figure 3.4.2 Liquid-Immersed Megavolt-Ampere Capacity Shipments, 2009 .............. 3-5 Figure 3.4.3 Dry-Type Unit Shipments, 2009 ................................................................ 3-6 Figure 3.4.4 Dry- Type Megavolt -Ampere Capacity Shipments, 2009 ........................... 3-6 Figure 3.5.1 Market Delivery Channels for Distribution Transformers ......................... 3-9 Figure 3.9.1 Transformer Losses Vary with Load (75 Kilovolt- Ampere Dry

- Type) ... 3-25 Figure 3.9.2 Transformer Efficiency Varies with Load ................................................ 3-26 Figure 3.9.3 Graphic of Symmetric Core Conf iguration .............................................. 3-303

- 1 CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMEN T

3.1 INTRODUCTION

This chapter provides a profile of the distribution transformer industry in the United

States

. The U.S. Department of Energy (DOE) developed the market and technology assessment presented in this chapter primarily from publicly available information

. This assessment is helpful in identifying the major manufacturers and their equipment characteristics, which form the basis for the engineering and life

- cycle cost (LCC) analyses.

3.2 DISTRIBUTION TRANSFO RMER DEFINITION S

The def inition of a distribution transformer was established in the Energy Policy Act (EPACT) of 2005, and further refined by DOE when it was codified into the Code of Federal Regulations (CFR) on April 27, 2006. 10 CFR 431.192; 71 FR 24972.

EPACT 2005 established that the definition of a distribution transformer would be as
follows:

“ The term 'distribution transformer' means a transformer that
- (i) has an input voltage of 34.5 kilovolts or less; (ii) has an output voltage of 600 volts or less; and (i ii) is rated for operation at a frequency of 60 Hertz.

The term 'distribution transformer' does not include – (i) a transformer with multiple voltage taps, the highest of which equals at least 20 percent more than the lowest; (ii) a transformer that is de signed to be used in a special purpose application and is unlikely to be used in general purpose applications, such as a drive transformer, rectifier transformer, auto -transformer, impedance transformer, regulating transformer, sealed and non- ventilating t ransformer, machine tool transformer, welding transformer, grounding transformer, or testing transformer; or (iii) any transformer not listed in clause (ii) that is excluded by the Secretary by
rule because (I) the transformer is designed for a special application; (II) the transformer is unlikely to be used in general purpose applications;
and (III) the application of standards to the transformer would not result in significant energy savings.

The term ‘low -voltage dry-type distribution transformer’ means a distribution transformer
that
- (A) has an input voltage of 600 volts or less;3

- 2 (B) is air

- cooled; and (C) does not use oil as a coolant.”

The term ‘transformer’ means a device consisting of two or more coils of insulated wire that
transfers alt ernating current by electromagnetic induction from one coil to another to change the original voltage or current value.

In the April 2006 final rule, DOE clarified some of the exemptions which were not defined in the statute, based on the test procedure rulemaking which had been developing the
definition of a distribution transformer

. These definitions were based primarily on industry sources including the Institute of Electrical and Electronics Engineers ( IEEE ) and the National
Electrical Manufacturers As sociation ( NEMA ). In addition, EPACT 2005 did not provide kVA ranges which were used by DOE in this rulemaking proceeding to bound its scope of coverage. Therefore, in the April 2006 final rule, DOE established kilovolt- ampere ( kVA ) ranges that were consistent with the scope of applicability for the test procedure and energy conservation standards rulemakings DOE had been conducting on distribution transformers. This means that DOE’s coverage authority granted by Congress is broader than that subset of distribution transformers that are being regulated in this proceeding.

3.3 EQUIPMENT CLASSES

DOE divides covered equipment into classes by: (a) the type of energy used; (b) the capacity; or (c) any performance

- related features that affect consumer utility or efficiency. (42 U.S.C. 6295(q)) Different energy efficiency standards may apply to different equipment classes

. In the previous rulemaking on distribution transformers with a final rule published in October 2007, DOE proposed 10 equipm ent classes and received general support on these equipment
classes . The 10 equipment classes divided up the population of distribution transformers by:

(a) Type of transformer insulation - liquid -immersed or dry-type, (b) Number of phases - single or th ree, ( c) Voltage class - low or medium (for dry-type units only), and ( d) Basic impulse insulation level (for medium

- voltage, dry -type units only).

Insulation type refers the medium used to electrically insulate and thermally cool a transformer’s windings . Although liquid insulations have advantages in both aspects, they pose an additional risk of leaking, catching fire, or catastrophic failure that dry-type units do not and, therefore, are almost exclusively limited to outdoor use. L ess efficient, dry

- typ e units offer additional utility to the consumer.

Number of phases refers to the type of electrical power that the transformer can process. Most power is transmitted in three -phase form over longer distances and split into its constituent phases at some p oint along the distribution chain. Three-phase units cannot be used in singlephase applications and, therefore, offer different utility to the consumer.

Voltage class refers to whether or not a transformer’s input voltage is above 600 (“medium”) or 600 and less (“low”). A transformer’s input voltage is dictated by the application3

- 3 requirements and so medium- and low-voltage transformers offer different util ity to the

consumer.

Finally, basic impulse insulation level refers to how resistant a transformer is to very large voltage transients (often arising from lightning strikes). It is related to both input voltage and likelihood of exposure to such transient s. Because both of those criteria are dictated by the transformer’s particular application, BIL can be said to offer additional utility to the consumer.
DOE has uses BIL to establish equipment classes only for medium-voltage, dry- type
transformers because it affects energy efficiency much more strongly there than in liquid

immersed and low-voltage units.

On August 8, 2005, the President signed into law EPACT 2005, which contained a provision establishing energy conservation standards for two of DOE ’s equipment classes ( ECs )— EC3 , low-voltage, single-phase, dry- type and EC4 , low-voltage, three-phase, dry- type

. With standards thereby established for low-voltage, dry-type distribution transformers, DOE no longer considered these two equipment classes for s tandards during the previous rulemaking. Since the current rulemaking is considering new standards for liquid -immersed and medium, dry- type voltage distribution transformers, DOE has decided to also revisit low-voltage, dry- type
distribution transformers t o determine if higher efficiency standards are justified

. Table 3.3.1 presents the ten equipment classes within the scope of this rulemaking analysis, and provides the kVA range associated with each.

Table 3.3.1 Distribution Transformer Equipment Classes

EC * # Insulation Voltage Phase BIL Rating kVA Range

EC 1 Liquid

- Immersed Medium Single

- 10

- 833 kVA

E C2 Liquid

- Immersed Medium Three

- 15

- 2500 kVA

E C3 Dry

- Type Low Single

- 15

- 333 kVA

E C4 Dry

- Type Low Three

- 15

- 1000 kVA

E C5 Dry

- Type Medium Single 20

- 45kV BIL 15

- 833 kVA

E C6 Dry

- Type Medium Three 20

- 45kV BIL 15

- 2500 kVA

E C7 Dry

- Type Medium Single 46

- 95kV BIL 15

- 833 kVA

E C8 Dry

- Type Medium Three 46

- 95kV BIL 15

- 2500 kVA

E C9 Dry

- Type Medium Single ≥ 96kV BIL 75

- 833 kVA

E C10 Dry

- Type Medium Three ≥ 96kV BIL 225

- 2500 kVA * EC = Equipment Class

Basic impulse insulation level (BIL) refer s to the level of insulation wound into a transformer, dictating its design voltage

. Generally, higher BIL ratings have lower transformer operating efficiencies because the additional insulation and necessary clearances increase the
distance between the cor e steel and the windings, contributing to higher losses. In addition, as the overall size of the windings increases due to additional insulation surrounding each wire, the core window through which the windings pass must increase, creating a larger core and increasing losses in the core . Recognizing this important aspect of transformer design, and after consultation with industry experts, DOE determined that differentiation of the energy efficiency standards by BIL level would be necessary for medium-volt age (MV), dry -type units, since these transformers experience significant variability in efficiency due to their BIL ratings

. This
decision is consistent with NEMA’s TP 1 -2002 (described in section 3.6.1 ).3

- 4 3.4 NATIONAL SHIPMENT ES TIMATE

To prepare an estimate of the national impact of energy conservation standards for distribution transformers, DOE needed to estimate annual transformer shipments

. For accuracy
in this c alculation, unit shipments were required by equipment class and kVA rating within each equipment class

. Detailed shipment information like this is highly sensitive to manufacturers, many of whom indicated to DOE they would not be able to disclose their shi pments. DOE researched public sources of transformer shipment information, such as the data compiled by the U.S. Census Bureau, but found that the data are aggregated, with many kVA ratings bundled in one value. Thus, DOE determined that it would not be po ssible to create an accurate estimate of transformers by kVA rating using U.S. Census Bureau data.

Instead, to develop its shipments estimate, DOE contracted a company with considerable knowledge of the U.S. transformer industry. This contractor has collectively more than 80 years of experience working in both the liquid-immersed and dry-type transformer industry in the U.S.

DOE tasked the contractor with using its knowledge of the market, plus a limited number of consultative calls, to compile a national estimate of shipments for liquid -immersed and dry- type
transformers.

Figure 3.4.1 through Figure 3.4.2 present the total aggregate shipment estimates for liquid

- immersed units, while Figure 3.4.3 through Figure 3.4.4 present low-voltage and mediumvoltage dry

- ty pe units. These pie charts show the estimated shipments for 2009 in both number of transformers and cumulative megavolt- ampere (MVA) of transformer capacity

. The superclasses are subdivided into two principal groups— single

- phase and three

- phase

. To simplify the illustrations, the single

- phase and three -phase medium-voltage, dry- type units are shown each as aggregat ions of the three equipment classes presented in Table 3.3.1 , where they are broken down by BIL rating. This was necessary as the separate market shares of medium

voltage, dry- type by BIL rating are small compared to the low -voltage, dry-type units. A detailed breakdown of the shipment estimates by equipment class and kVA rating appears in the shipments analysis (Chapter 9 of this TSD).3

- 5 Figure 3.4.1 Liquid

- Immersed Unit Shipments , 2009

Figure 3.4.2 Liquid

- Immersed M egavolt- Ampere Capacity Shipments , 2009 Liquid
1

- Phase

93% Liquid
3

- Phase

7%

Liquid
1

- Phase

41% Liquid
3

- Phase

59%3

- 6 Figure 3.4.3 Dry

- Type Unit Shipments , 2009

Figure 3.4.4 Dry

- Type M egavolt- Ampere Capacity Shipm ents, 2009

Table 3.4.1 presents the actual shipment estimates by equipment class and the estimated value of these shipments, approximately $2.09 billion in 2009. Dry

- LV
1

- Phase

8%

Dry

- MV
1

- Phase

0.6% Dry

- LV
3

- Phase

90% Dry

- MV
3

- Phase

1.7%

Dry

- LV 1

- Phase

3%

Dry

- MV 1

- Phase

0.2% Dry

- LV 3

- Phase

70% Dry

- MV 3

- Phase

27%3

- 7 Table 3.4.1 National Distribution Transformer Shipment Estimates for 2009

Distribution Transformer Equipment Class Units Shipped MVA Capacity Shipped Shipment Value (200 9 US$million) Liquid

- immersed, medium

- voltage, single

- phase 683,726 21,994 714.8 Liquid

- immersed, medium

- voltage, three

- phase 49,739 32,266 786.0 Dry

- type, low

- voltage, single

- phase 17,740 647 22.0 Dry

- type, low

- voltage, three

- phase 206,929 15,778 394.4 Dry

- type, medium

- voltage, single

- phase, 20

- 45 kV BIL 709 23 0.7 Dry

- type, medium

- voltage, three

- phase, 20

- 45 kV BIL 522 257 6.2 Dry

- type, medium

- voltage, single

- phase, 46

- 95 kV BIL 546 23 0.8 Dry

- type, medium

- voltage, three

- phase, 46

- 95 kV BIL 2,074 3,655 98.7 Dry

- type, medium

- voltage, single

- phase, ≥ 96 kV BIL 202 9 0.3 Dry

- type, medium

- voltage, three

- phase, ≥ 96 kV BIL 1,286 2,206 66.2

Total 963,473 76,858 2,090.1

The liquid- immersed transformer market accounted for 76 percent of the distribution transformers sold in the United States in 2009 (on a unit basis). These transformers accounted for 71 percent of the distribution transformer capacity measured in MVA, and 72 percent of the dollar value of the 2009 shipments. On a unit basis, more than 93 percent of the liquid- immersed shipments are single-phase. However, these single -phase units tend to have lower kVA ratings than the three-phase units, which are more than 59 percent of the total MVA capacity shipped of liquid -immersed distribution transformers in 2009.

In the dry-type market, low-voltage, three- phase distribution transformers dominate, accounting for 90 percent of units and 70 percent of MVA shipped. Medium

- voltage, three

- phase units accounted for only 1.7 percent of the units shipped, but were 27 percent of MVA shipments in 2009. The low-voltage, single-phase units were about 8 percent of the dry-type units shipped; however, because their kVA ratings tend to be small, they only accounted for about 3 percent o f
all dry-type MVA shipments in 2009. Medium- voltage, single -phase units occupy a small part of the market, representing 0.6 percent of the dry-type units shipped and 0.2 percent of dry- type MVA shipped.

In preparing its estimates of the distribution tran sformer market, DOE ’s contractor
identified several key insights to place the 2009 shipment estimates into perspective.

1. Fundamentally, 2009 was characterized by slow housing starts, minimal industrial and commercial activity, and general retrenchment in the country.

2. Distribution transformer shipments reflected the slow economic activity in all segments.

3. The data for 2009 looked relatively weak compared to DOE’s previous distribution
transformer market size estimate from 2001.

a. Liquid- immersed, single -phase distribution transformer unit shipments were down 30 percent but up substantially in price, reflecting higher material costs.3

- 8 b. Liquid- immersed, three -phase distribution transformer unit shipments were down 37.5 percent but up in both price and average size, with significant increases in data center applications.

c. Low -voltage, dry-type distribution transformer unit shipments were down 33 percent as a reflection of the units largely being short lead

- time, off -the- shelf items that are easily defra yed in tight business conditions for better times.

d. Medium-voltage, dry- type distribution transformer unit shipments were actually up in 2009 compared to past years. This is attributable to the fact that these are long lead

- time items, and many were ordere d during the high economic growth period in 2008. Additionally, some purchases were likely expedited in 2009 to beat the DOE energy conservation standards that took effect in the beginning of

2010.

3.5 MANUFACTURERS OF DISTRIBUTION TRANSFORME RS

In total, there are more than 60 manufacturers and importers of distribution transformers operating in the U.S. today. 1 Of these, 16 major companies represent about 80 percent of both the liquid -immersed and dry- type markets.

From a manufacturing point of view, the six largest companies operating in the liquid

immersed distribution transformer market are (in alphabetical order): ABB Power T&D Company, Cooper Power Systems, Electrical Repair and Maintenance Company ( ERMCO ),
Howard Industries , Power Partners , and Prolec

- Ge neral Electric . Together, these six companies represent more than 80 percent of the sales revenue of liquid

- immersed distribution transformers
in the U nited States

.

For low-voltage dry-type distribution transformer manufacturers, the seven largest

compan ies operating in the U nited States include (in alphabetical order): Acme Electric Corporation, Eaton Electrical, Inc., Federal Pacific Transformer Company, General Electric, Hammond Power Solutions Inc., Olsun Electrics Corporation, and Square D Company. Together, these companies represent more than 80 percent of the sales revenue of low-voltage dry- type distribution transformers in the U.S.

For medium-voltage dry-type distribution transformers manufacturers, the seven largest companies operating in the U.S. include (in alphabetical order): ABB Power T&D Company, Federal Pacific Transformer Company, Hammond Power Solutions Inc., Jinpan International
Ltd. , Magnetic Technologies Corp. , MGM Transformer Company, and Olsun Electrics

1 This estimate is based on a review of the Thomas Business Registry (June 2005), United Laboratories (UL) Listings (June 2005), Canadian Standards Association (CSA) Listings (June 2005), Factory Mutual (FM) Listings (June 2005), the ORNL contact database from the Determination Analysis, and participants in DOE’s Distribution Transformers Framework Workshop meeting held November 1, 2000 in Washington, DC.3

- 9 Corporation. Together, thes e companies represent more than 80 percent of the sales revenue of
medium- voltage dry -type distribution transformers in the U nited States

.

3.5.1 Potential Small Business Impacts

DOE is considering the possibility of small businesses being impacted by the promulgation of amended minimum efficiency standards for distribution transformers

. DOE is aware that there are small distribution transformer manufacturers, defined by the Small Business
Administra tion as having 750 employees or fewer, who would be impacted by a minimum efficiency standard

. DOE studies the potential impacts to these small businesses in greater detail during the manufacturer impact analysis (MIA)

. Please see Chapter 12 for greater de tail on this analysis.

3.5.2 Distribution and Sales Channels

A schematic of the distribution transformer mar ket is shown in Figure 3.5.1

. i This illustration depicts the major market players and the level of interaction between them . The solid lines show more common distribution and sales channels and dashed lines less frequently used
channels.

Figure 3.5.1 Market Delivery Channels for Distribution Transformers

The market delivery channel for electric utilities is generally direct, with the majority of these customers placing orders directly with manufacturers. It is estimated that electric utilities purchase over 90 percent of their distribution transformers directly from manufacturers, specifying their desired features and performance. i There are also utilities, such as some rural cooperatives and municipalities, that make transformer purchases through distributors. When placing an order, the electric utility provides a specification, including the value it places on3

- 10 future core and coil losses over the life of the transformer (see section 3.6 for a discussion of total owning cost). This market dynamic leads manufacturers to develop custom designs in their
contract bid s , reflecting the customer’s performance requirements and the dynamic costs of material, equipment, and labor at a transformer manufacturer’s facility.

The delivery channel for commercial and industrial customers can be complex, working through intermediaries such as stocking distributors and electrical contractors. Electrical contractors typically purchase transformers using specifications written by themselves or by
agents

. Some larger industrial customers buy transformers directly from distributors or manufacturers based on specifications drafted by in -house exper ts

. Any large -volume or customorder purchases made (e.g., orders from the petrochemical or the pulp and paper industry) are typically made directly with transformer manufacturers

. Similarly, original equipment manufacturers (OEMs) know the exact specifica tion s they require for their finished equipment and typically work directly with manufacturers when placing an order.

Transformers with major damage are usually replaced rather than repaired . However, when a repair does take place (e.g., when failure occu rs within the warranty period), it may be carried out by a repair shop or at the manufacturer’s facility

. Additionally, some utilities may choose to carry out their own repairs if this option is less expensive than disposal and replacement.

3.6 TOTAL OWNING COST EVALUATION

In 1995, there were an estimated 44 million liquid- immersed distribution transformers in service, of which approximately 90 percent were owned by electric utilities. i For dry- type transformers, there were approximately 12 million units in service, which were primarily used by
commercial and industrial customers. i The liquid- immersed market, dominated by the electric utility sector, drove efficiency ratings higher over time, encouraging more efficient materials and manufacturing methods. A detailed discussion of these improvements and efficiency trends between the years 1950 and 1993 can be found in two Oak Ridge National Laboratory ( ORNL )
reports. i

, ii

Following the energy price shocks of the 1970s, utilities started using total owning cost (TOC) evaluation formulas ( Equation 3.6.1 ), incorporating core and winding losses into their purchasing decisions. The TOC consists of the quoted transformer price and energy losses in the core and winding over the anticipated life of the unit.

Expressed as a formula,

Equation 3.6.1 TOC = (NL **×** A) + (LL **×** B) + Price

where:

TOC = total owning cost ($),

NL = no

- load loss (Watts),3

- 11 A = equivalent first -cost of no- load losses ($/Watt),

LL = load loss at the transformer’s rated load (Watts),

B = equivalent first -cost of load losses ($/Watt), and

Price = bid price (retail price)($).

The capitalized cost per watt of no -load and load losses, the A and B factors, vary from one electric utility to another

. They a re derived from several variables, including the avoided costs of system capacity, generation capacity, transmission and distribution capacity and energy,
the level ed fixed charge rate, the peak responsibility factor, the transformer loss factor, and the equivalent annual peak load. iii For a detailed discussion on the development and use of the TOC formula, including examples, see the draft industry standard document, Institute of Electrical and Electronics Engineers, Inc. (IEEE) PC57.12.33.

Utilities that use A and B factors compare two or more proposals from manufacturers and select the one that offers them the lowest total owning cost (i.e., the lowest combination of first cost and operating cost over the life of the transformer). Before electric utility deregulation started in North America, 30 years was considered the standard operating life and the depreciation period of a liquid- immersed transformer . Deregulation has raised concerns about payback periods, since electric utilities are not sure if they will own the transformer for its entire
life

. This uncertainty has forced some electric utilities to reduce their A and B factors, equating to a decreased emphasis on losses and

, therefore

, transformer efficiency ratings.

In 1996, ORNL estimated that “more than 90 percent” of electric utilities used the TOC method of loss evaluation at the time of purchase, which drove the market toward increasingly efficient designs. i More recently, however, the possibility of deregulation and the associated sale of distribution networks has meant that utilities purchasing transformers today may not own them in 5 or 10 years, and t hus will not recover the higher initial cost of a more efficient design

. These regulatory changes and the general uncertainty surrounding deregulation have driven some utilities to purchase designs with lower first costs and higher losses.

Similarly, DOE’ s final rule for distribution transformers that was published in October
2007 has caused some utilities to reexamine their A and B factors

. DOE is aware that some utilities have deemphasized the importance of A and B factors and placed more emphasis on
low er first costs as a result of the minimum effi ciency standards . Through conversations with industry professionals and manufacturers, DOE believes that many utilities still maint ain
awareness of a total owning cost approach, but sometimes find that such an approach would dictate an efficiency level below the federal standard and therefore purchase at that threshold

. Furthermore, many utilities have critically examined their A and B factors in response to the 2007 rulemaking, and have altered their A and B factors in response.

The IEEE draft standard PC57.12.33 has a chapter discussing transformer efficiency for
commercial and industrial customers iii (i.e., typical users of dry- type transformers) , but the market itself appears split between the medium -voltage and the low-voltage units. The mediumvoltage, dry- type transformer market functions similarly to the liquid

- immersed market, in that
manufacturers receive custom

- build orders with specifications or design criteria from customer s. Because these customers pay for (and are concerned about) the electricity lost in their own3

- 12 distribution systems, they are concerned about the performance of the transform ers they order

. The low-voltage, dry- type transformer market does not participate in the manufacturing process; instead these units are generally sold “off-the- shelf” or on a catalog stock order basis. Most of the low-voltage, dry- type transformers installed inside buildings or plants are purchased by electrical contractors or building managers who are not responsible for paying future energy
bills . Thus, the designs of these transformers are commonly driven toward the lowest first-cost,
lower effici ency units. This trend was identified by ORNL.

3.6.1 Voluntary Programs

DOE reviewed several voluntary programs promoting efficient distribution transformers
in the United States . When DOE’s previous rulemaking for distribution transformers took effect in January of 2010, many voluntary programs ended. This is because the minimum efficiency requirements were greater than or equal to the efficiency level dictated by the voluntary program, or the program needed revising in light of the new standard levels.

In this section, DOE considers several voluntary programs that are still operating, and several programs that recently became inactive

. These include the NEMA Standards Publication

TP 1

, Guide for Determining Energy Efficiency for Distribution Transformers

, (NEMA TP 1)
and NEMA Premium Standard , the Federal Energy Management Program’s TP 1 purchase program, the U.S. Environmental Protection Agency’s Energy Star Transformers program, and the Consortium for Energy Efficiency’s Commercial and Indu strial Transfo rmers Initiative

. DOE also reviewed several voluntary programs operating at a regional level that offer custom incentive programs for distribution transformers, such as the programs offered by National Grid and Seattle City Light.

3.6.2 National Electrical Manu facturers Association TP 1 Standard

The NEMA TP 1 standard establishe d a voluntary efficiency standard for distribution
transformers. iv It encompasse d liquid

- immersed distribution transformers, single - and threephase, as well as dry -type, low-voltage and medium- voltage, single
- and three -phase units. The

e fficiency levels for liquid -immersed and medium-voltage dry-type distribution transformers

were superseded , though, by DOE’s final rule, published in October 2007. Additionally, Congress established NEMA TP 1 as the standard for low-voltage dry- type transformers (EPACT 2005, August 8

, 2005). Therefore, the NEMA TP 1 standard levels are no longer voluntary, but required.

NEMA established this national voluntary efficiency standard in 1996, and revised it in

2002. v Table

3.6.1 Manufacturers had to meet or exceed the minimum efficiency targets presented in
and Table 3.6.2 at the appropriate loading points. At that time, NEMA TP 1 efficiency
levels were adopted by States and other agencies that were interested in establishing a standard

. More information about NEMA TP 1 can be obtained by contacting NEMA, tel: 703-841-3200, or by visiting http://www.nema.org/Products/Pages/Transformers.aspx

.3

- 13 Table 3.6.1 N ational Electrical Manufacturers Association TP 1 Efficiency Levels for Liquid

- Immersed Distribution Transformers
Liquid

- Immersed, Single

- Phase Liquid

- Immersed, Three

- Phase

kVA Min Efficiency (%) kVA Min Efficiency (%)

10 98.3 15 98.0

15 98.5 30 98.3

25 98.7 45 98.5

37.5 98.8 75 98.7

50 98.9 112.5 98.8

75 99.0 150 98.9

100 99.0 225 99.0

167 99.1 300 99.0

250 99.2 500 99.1

333 99.2 750 99.2

500 99.3 1000 99.2

667 99.4 1500 99.3

833 99.4 2000 99.4

- - 2500 99.4

Notes: Temperature: load

- loss 85  ̊ C, no

- load loss 20  ̊ C Efficiency levels at 50 percent of unit nameplate load

Table 3.6.2 National Electrical Manufacturers Association TP 1 Efficiency Levels for Dry

Type Distribution Transformers
Dry

- Type, Single

- Phase Dry

- Type, Three

- Phase

kVA Min Efficiency (%)

kVA Min Efficiency (%)

Low

Voltage Medium

- Voltage Low

Voltage Medium

- Voltage
≤60 kV BIL >60 kV BIL ≤60 kV BIL >60 kV BIL

15 97.7 97.8 97.6 15 97.0 97.2 96.8

25 98.0 98.1 97.9 30 97.5 97.6 97.3

37.5 98.2 98.3 98.1 45 97.7 97.8 97.6

50 98.3 98.4 98.2 75 98.0 98.1 97.9

75 98.5 98.5 98.4 112.5 98.2 98.3 98.1

100 98.6 98.6 98.5 150 98.3 98.4 98.2

167 98.7 98.8 98.7 225 98.5 98.5 98.4

250 98.8 98.9 98.8 300 98.6 98.6 98.5

333 98.9 99.0 98.9 500 98.7 98.8 98.7

500

- 99.1 99.0 750 98.8 98.9 98.8

667

- 99.2 99.0 1000 98.9 99.0 98.9

833

- 99.2 99.1 1500

- 99.1 99.0

- - - - 2000

- 99.2 99.0

- - - - 2500

- 99.2 99.1

Notes: Temperature: 75  ̊ C for both low

- and medium

- voltage

Low

- voltage efficiency levels at 35 percent of unit nameplate load
Medium

- voltage efficiency levels at 50 percent of unit nameplate load

3.6.3 National Electrical Manufacturers Association

– NEMA Premium Program

The NEMA Premium program establishes a voluntary efficiency standard for lowvoltage, dry- type distribution transformers

. It encompasses both single- and three

- phase low

voltage, dry -type units. For a low-voltage, dry-type distribution transformer to qualify as NEMA3

- 14 Premium, it m ust have 30 percent fewer losses than the NEMA TP 1 level

. NEMA established this national voluntary efficiency program in July 2010 . Manufacturers must meet or exceed the minimum efficiency targets presented in Table 3.6.3 at the appropriate loading points. More
information about NEMA Premium can be obtained by contacting NEMA, tel: 703 -841-3200, or by visiting http://www.nema.org/Technical/Pages/NEMA

- Premium

- Efficiency

- Transformers

Program.aspx

.

Table 3.6.3 NEMA Premium Efficiency Levels for Low -Voltage, Dry- Type Distribution
Transformers
Single

- Phase Three

- Phase

kVA Min Efficiency (%) kVA Min Efficiency (%)

15 98.39 15 97.90

25 98.60 30 98.25

37.5 98.74 45 98.39

50 98.81 75 98.60

75 98.95 112.5 98.74

100 99.02 150 98.81

167 99.09 225 98.95

250 99.16 300 99.02

333 99.23 500 99.09

- - 750 99.16

- - 1000 99.23

Note: E fficiency levels at 35 percent of unit nameplate load

.

3.6.4 Energy Star Transformers

The U.S. Environmental Protection Agency (U.S. EPA) and DOE manage d a program called Energy Star Transformers to overcome market barriers preventing industrial/commercial customers and utilities from purchasing more energy

- efficient, dry -type, low-voltage, single- and
three -phase units. The minimum efficie ncy that a transformer had to meet or exceed to be classified as an Energy Star transformer wa s the same as NEMA’s TP 1

. The activities of this program included use of the Energy Star label, marketing assistance to manufacturers and distributors, and free software tools for end users (including a downloadable cost evaluation model and an energy

- efficiency calculator) . This program wa s sponsored and promoted by th e U.S. EPA and DOE, with additional promotional support from the Consortium for Energy Efficiency (CEE).

The Energy Star Transformers program was suspended on May 1, 2007 because EPACT
2005 established NEMA TP 1 as the standard for low-voltage dry- type tr ansformers

. For more information or questions about this program, please contact the U.S. EPA tel: 1-888- STAR

- YES
or visit http://www.epa.gov/ ; or CEE, tel: 617-589-3949, or visit http:// www.cee1.org/

.

3.6.5 Consortium for Energy Efficiency

The CEE’s Commercial and Industrial Transformers Initiative, launched in 1997, promoted the manufacture and sale of high

- efficiency transformers. Historically, CEE and its members partnered with the Energy Star Transformers Program to promote high- efficiency3

- 15 performance guidelines for low -voltage distribution transformers specified by the NEMA TP 1
standard

. CEE members and other participating organizations include electric utilities, and statewide or regional efficiency organizations, which may be utility

- based . CEE published an Initiative Description and Market Assessment , which identifies the transformer market barriers to efficiency for interested utilities and other organizations

. In 2012 CEE was updatin g its high

efficiency transformer specification . For more information, contact CEE at tel: 617 -337-9274.

3.6.6 Federal Energy Management Program

DOE manages the Federal Energy Management Program (FEMP), which helps Federal buyers identify and purchase energy- ef ficient equipment, including distribution transformers. The FEMP standard for distribution transformers is based on the NEMA TP 1 standard, and
includes all units listed in TP 1

. While the liquid -immersed and medium- voltage dry

- type recommendations (based on NEMA TP 1) are superseded by DOE’s 2007 final rule, FEMP still offers buyers support tools such as efficiency guidelines, cost- effectiveness examples, and a cost
calculator . FEMP also offers training, on-site audits, demonstrations, and design assistance. For more information, interested stakeholders can contact FEMP at tel: 1-202-586-5772, or visit http://www1.eere.energy.gov/femp/

.

3.6.7 National Grid

National Grid offers a custom measure incentive for energy efficient replacement
distribution transformers

. Each transformer purchase is evaluated independently based on first costs and energy savings (annually and during peak loading) compared to the existing
transformer . If the replacement distribution transform er passes National Grid’s custom criteria, up to 50 percent of the first costs can be reimbursed, capped at a 1.5 year payback and based on a dollar cost per unit of savings. For more information, contact National Grid at 1-781-907-1000 or efficiency@us.ng rid.com.

3.6.8 Seattle City Light

Seattle City Light manages the Energy Smart Services Custom Incentive Program. vi

3.7 REGULATORY PROGRAMS The program provides incentives for distribution transformers that exceed the NEMA TP 1 standards
for low -voltage, dry-type distribution transfo rmers . Incentives provided cover up to 70 percent of the cost for qualifying equipment, or $0.23 per k ilowatt -hour saved

. Usually incentives are applied to utility

- owned equipment. For more information contact Seattle City Light at tel: 206

- 684-3000, or visit www.seattle.gov/light/

.

On August 8, 2005 the President signed into law EPACT 2005. This legislation
establishe d the energy conservation standard for low-voltage, dry-type distribution transformers at the industry voluntary program level of NEMA TP 1 -2002. This Federally mandated standard is the national standard, preempting any State efficiency standards for th is ty pe of equipment3

- 16 when it took effect on January 1, 2007. At the international level, DOE is aware of standards in both Canada and Mexico that may impact the companies servicing the North American market

. Summaries of these regulatory programs are provided i n this section.

3.7.1 U.S. National Energy Bill – E nergy Policy A ct of 2005

The U.S. Congress enacted legislation requiring that low-voltage, dry- type transformers manufactured on or after, or imported into the U.S. on or after January 1, 2007, meet the NEMA

TP 1 minimum efficiency standards:

LOW VOLTAGE DRY TYPE DISTRIBUTION TRANSFORMERS.

— The efficiency of
a low -voltage dry-type distribution transformer manufactured on or after January 1, 2007, shall be the Class I Efficiency Levels for distribution transfor mers specified in table 4 –2 of the ‘Guide for Determining Energy Efficiency for Distribution Transformers’ published by the National Electrical Manufacturers Association (NEMA TP–1–2002).

During DOE’s previous rulemaking on distribution transformers, DOE adopted the

NEMA TP 1 -2002 standard level set by EPACT 2005. As such, DOE no longer considered lowvoltage, dry-type transformers in that analysis, and published a final rule in 2007 that contained new standards for only liquid-immersed and medium- voltage, dry -type units. At this point in time, DOE has revisit ed low-voltage, dry-type distribution transformers to see if higher standard
levels are warranted.

3.7.2 Canadian Efficiency Standard

The Canadian Government regulates efficiency of dry

- type transformers . The regulation mandates compliance with the efficiency values listed in Canadian Standards Association (CSA)
standard C802.2-00 as of January 1, 2005 (Canada Gazette, April 10, 2003). Liquid- immersed distribution transformers are addressed by a voluntary program, which has been drafted to allow supervisory oversight by the Canadian Government.

In June 1997, the Office of Energy Efficiency at Natural Resources Canada (NRCan) announced that it intended to develop regulated minimum performance standards for
transformers . These proposed regulations would affect interprovincial trade and transformers imported into Canada. Consultative workshops followed this announcement, which included discussion around harmonizing with NEMA's TP 1 levels.

The CSA drafted and published CSA C802.2- Minimum Efficiency Values for Dry Type Transformers , in which efficiency is measured according to a per unit loading of 35 percent for low-voltage and 50 percent for medium-voltage. The efficiency levels are the same as NEMA TP

1 exce pt the CSA added an additional significant digit (zero) in the hundredths place. For this standard, the reference winding temperature is 75  ̊C, as in NEMA's TP 1 . An amendment proposed in June 2010 would result in increasing the standard levels for medium-v oltage dry

type to align with the current DOE standards. At the publication of this document, however,
NRCan MVDT standards remained below those of DOE.3

- 17 As a result of the process of working with the CSA and a range of stakeholders, NRCan chose to separat e the regulatory processes for liquid-immersed and dry- type transformers.

Liquid-Immersed Transformer Standards

The process of regulating minimum efficiency levels for liquid

- immersed transformers was stopped after several years of development

. The CSA h armonized the Canadian standard with NEMA’s voluntary standards, selecting the range of regulated equipment , the efficiency levels, and the transformer test procedures based on NEMA TP 1 and TP 2. However, a market analysis revealed that the liquid

- immerse d transformer market in Canada is dominated by the nine provincially operated electric utilities, each of which had already incorporated energy efficiency into their transformer procurement practices . It was found that more than 95 percent of the liquid

- im mersed distribution transformers sold in Canada already met the NEMA TP 1 efficiency levels.

Thus, the Canadian Government decided not to continue with the development of a regulation for liquid- immersed distribution transformers

. Instead, the major Canadian utilities and manufacturers, through the Canadian Electricity Association (CEA), signed a voluntary agreement with NRCan

. Under the terms of this agreement, the electric utilities agreed to adopt the minimum efficiency levels ba sed on the CSA C802.1-00 standard when purchasing liquidfilled transformers, and to report the performance of virtually all liquid- immersed transformers
installed in Canada to NRCan

. NRCan will then determine if the efficiency of the market is degrading and, if so, take appropriate action.

Dry -Type Transformer Standards

NRCan pre-published an amendment to Canada’s regulations that includes dry- type transformers on December 14, 2002. This amendment was published on April 23, 2003. This minimum energy perf ormance standard for dry- type transformers became effective on January 1, 2005. The regulations included a broad range of kVA ratings, more than are included in NEMA TP 1 or the Department of Energy’s rulemaking on distribution transformers.

A consultation forum was organized in June 2005 by NRCan with the objective of analyzing some issues pertaining to the Canadian regulation. As a result of this focus, some changes were made to the regulation and modifications proposed to the CSA C802.2 S tandard

. Meeti ngs were convened in July and September 2005 involving of NRCan, the CSA C802.2 subcommittee, transformer manufacturers and other stakeholders to address these issues. At these meetings, some of the key changes to the dry

- type transformer regulation agreed were:

**•** Elimination of the tap range exemption, so there is no exemption in the Canadian regulations based on a tap range.

**•** Addition of an exemption for furnace transformers. This exemption was necessary due to the removal of the tap range exemption. Furna ce transformers were defined as "a three

phase step -down transformer that is designed to be connected to an electric- arc furnace,3

- 18 and has a delta

- wye switching arrangement plus high

- voltage taps for changing the level of the low voltage supplied to the fur nace."

**•** Exclusion of drive transformers with two or more output windings or a low-voltage line current larger than 1500 a mperes . This means that drive transformers designed with one output winding and a low-voltage line current less than or equal to 1500 A mperes are subject to regulation.

**•** Clarification that transformers with resin

- cast coils (not encapsulated cores) are covered by the regulation . The exemptions for sealed transformers and non- ventilated transformers do not apply to resin- cast coil transformers.

**•** Elimination of the minimum low -voltage values, and addition of a maximum low- voltage
line current of 4000 a mperes

.

In addition, the following change was made to the CSA dry- type performance standard, and this change may be incorporated in the Energy Efficiency Regulations in a future
amendment:

**•** Adoption of two BIL groupings for medium- voltage dry -type transformers, consistent with the BIL groupings in NEMA TP 1-2002.

At the September 2005 meeting, an amendment to the definition of a dry- type transformer was also agreed as follows:

Dry -type transformer means a transformer, including a transformer that is incorporated into any other product, in which the core and coils are in a gaseous or dry compound insulating medium and that

(a) is either single-phase with a capacity from 15 to 833 kVA or three-phase with a capacity from 15 to 7500 kVA, and (b) has a nominal frequency of 60 Hz,

but does not include transformers having a rated low voltage line current larger than

4000 a mperes

.

Additiona l amendments were made by NRCan in the following years, and most recently in June 2010, NRCan pre-published proposed amendments to regulations. (Canada Gazette Part I, June 12, 2010) The amendments proposed the following changes:

**•** Increase existing standa rds for single- and three- phase dry

- type transformers to
harmonize with DOE standards.

**•** Increase the scope of coverage to include transformers with a BIL up to 199 kVA. DOE’s standards have an upper limit of 150 kVA.3

- 19 **•** Adopt exclusions for the following transformers: special impedance, grounding, furnace, resistance grounding, and on

- load regulating.

**•** Remove exclusions for “transformers with tap ranges of 20%, uninterruptible power supply transformers, instrument transformers, machine tool (control) transformers, and encapsulated transformers.”

**•** “Scale efficiency values for three -phase units with a rating between 3,000 to 7,500 kVA,” which are not covered by the U.S. standards.

**•** Adopt a “more stringent table of normal impedance ranges (i.e., units with an impedance level that fell outside the normal impedance ranges would be excluded from the [minimum efficiency performance standards]).”

Table 3.7.1 presents the current minimum efficiency requirement s for dry- type transformers.3

- 20 Table 3.7.1 Canadian Minimum Efficiency Standards for Dry

- Type Transformers
January 1, 2005 January 1, 2010 Percentage efficicency at
35% nominal load Percentage efficiency at 50% nominal load

Single

- phase kVA rating 1.2 kV Class 20

- 45kV BIL 46

- 95kV BIL 96

- 199kV BIL

15 97.70 98.10 97.86 97.6

25 98.00 98.33 98.12 97.9

37.5 98.20 98.49 98.30 98.10

50 98.30 98.60 98.42 98.20

75 98.50 98.73 98.57 98.53

100 98.60 98.82 98.67 98.63

167 98.70 98.96 98.83 98.80

250 98.80 99.07 98.95 98.91

333 98.90 99.14 99.03 98.99

500

- 99.22 99.12 99.09

667

- 99.27 99.18 99.15

833

- 99.31 99.23 99.20

Three

- phase kVA rating 1.2 kV class 20

- 45kV BIL 46

- 95kV BIL 96

- 199kV BIL

15 97.00 97.50 97.18 96.80

30 97.50 97.90 97.63 97.30

45 97.70 98.10 97.86 97.60

75 98.00 98.33 98.12 97.90

112.5 98.20 98.49 98.30 98.10

150 98.30 98.60 98.42 98.20

225 98.50 98.73 98.57 98.53

300 98.60 98.82 98.67 98.63

500 98.70 98.96 98.83 98.80

750 98.80 99.07 98.95 98.91 1,000 98.90 99.14 99.03 98.99 1,500

- 99.22 99.12 99.09 2,000

- 99.27 99.18 99.15 2,500

- 99.31 99.23 99.20 3,000

- 99.34 99.26 99.24 3,750

- 99.38 99.30 99.28 5,000

- 99.42 99.35 99.33 7,500

- 99.48 99.41 99.39

Note: At 50 percent unit nameplate load.

3.7.3 Mexican Efficiency Standard

Mexico is one of the regional leaders in promoting and regulating energy effi cient
transformers . In recent years, other countries, such as Argentina, Ecuador, and Peru, have requested assistance from Mexico in the development and implementation of national efficiency

programs.

Mexico began regulating distribution transformers more than three decades ago when it
enacted NOM -J116 in 1977. vii However, in 1989, a presidential decree modified the Normas Oficiales Mexicanas (Official Mexican Standards) from mandatory to voluntary standards;3

- 21 NOM

- J116 became NMX

- J116, a Norma Mexicana (Mexican Standard) . In 1992, the Ley Federal sobre Metrología y Normalización (Federal Law on Metering and Standards) re

established the mandatory character of NOMs . In addition, this law empowered the Secretaría de Energía (the Mexican equivalent to the U .S. Department of Energy) to formulate and enact mandatory standards for electrical equipment.

A new mandatory standard was enacted in 1994, NOM-001- SEMP -1994, to regulate the energy efficiency and safety of electrical equipment including distribution transf ormers . In 1997, Mexico’s government proposed a revision to NOM-001, and also proposed a new standard,

NOM -002- SEDE -1997. viii NOM -002 was published in the Diario Oficial de la Federación (Official Registry) for public revision and enacted two years later in October 1999.

In 2010, NOM- 002 was revised to update several aspects of the standard . The new version of the document, NOM-002- SEDE -2010, was approved by the Comité Consultivo Nacional de
Normalizaci ón de Instalaciones El éctricas (CCNNIE) on July 8, 2010. Once it is published in the
Diario Oficial de la Federaci ón , the new standard will take effect six months later.

This standard, which regulates liquid-immersed units, is the only compulsory efficiency regulation of distribution transformers in Mexico. Dry -type distribution transformers are used in Mexico, but neither government nor industry has moved to regulate them. Table 3.7.2 presents the characteristics of reg ulated distribution transformers in Mexico.

Table 3.7.2 Characteristics of Regulated Distribution Transformers in Mexico

Characteristic Specification

P ower Supply Single

- phase

Three

- phase

Nominal Capacity 5 to 167 kVA (single

- phase)

15 to 500 kVA (three- phase)

Insulation Class Up to 95 kV BIL ( Up to 15 kV )
Up to 150 kV BIL (Up to 25 kV)
Up to 200 kV BIL (Up to 34.5 kV)

Installation Application Pad; Pole; Substation; Submersible

Status of Transformer Newly purchased
Repaired/Refurbished

NOM -002 provides two sets of tables with the specified minimum efficiency levels and the unit losses in watts, both tested at 100 percent of nameplate load. Since the requirements in

NOM -002 are based on 100 percent loading, they are not directly comparable to DOE’s efficiency standards

. Table 3.7.3 and Table 3.7.4 show the efficiency requirements under NOM002, which were left unchanged in the 2010 revision of the standard. However, w hile the previous version of NOM-002 allowed a less stringent standard for small manufacturers with
cumulativ e annual production under 9 kVA, the 2010 version has removed this provision. This is3

- 22 partially because the reduced standards for small manufacturers were not typically applied in practice, and many small manufacturers were complying at the same efficiency level as the large
manufacturers.

While there is only one mandatory standard for distribution transformers, there are
several v oluntary Mexican standards. This description only deals with the mandatory standards.

Table 3.7.3 Minimum Efficiency Levels for Transformers in Mexico

Type Capacity

[ kVA ] Insulation Class

Up to 95 kV BIL

( Up to 15 kV )

[%] Up to 150 kV BIL

( Up to 25 kV )

[%] Up to 200 kV BIL

(Up to 34.5 kV)

[%]

Liquid

- Immersed, Single

- Phase 5 97.90 97.80 97.70

10 98.25 98.15 98.05

15 98.40 98.3 98.2

25 98.55 98.45 98.35

37.5 98.65 98.55 98.45

50 98.75 98.65 98.55

75 98.90 98.80 98.70

100 98.95 98.85 98.75

167 99.00 98.90 98.8 0

Liquid

- Immersed

, Three

- Phase 15 97.95 97.85 97.75

30 98.25 98.15 98.05

45 98.35 98.25 98.15

75 98.50 98.40 98.30

112.5 98.60 98.50 98.40

150 98.70 98.60 98.5 0

225 98.75 98.65 98.55

300 98.80 98.70 98.60

500 98.90 98.80 98.7 0

Note: These efficiency levels are applicable at 100 percent of nameplate load , and do not include losses from protective accessories.3

- 23 Table 3.7.4 Maximum Allowed Losses for Transformers in Mexico

Type Capacity [ kVA ] Insulation Class

Up to 95 kV BIL

(Up to 15 kV)

[Watts] Up to 150 kV BIL

(Up to 25 kV )

[Watts] Up to 200 kV BIL

(Up to 34.5 kV)

[Watts]

Core

Losses Total
Losses Core

Losses Total
Losses Core

Losses Total
Losses

Liquid

Immersed,

Single

Phase 5 30 107 38 112 63 118

10 47 178 57 188 83 199

15 62 244 75 259 115 275

25 86 368 100 394 145 419

37.5 114 513 130 552 185 590

50 138 633 160 684 210 736

75 186 834 215 911 270 988

100 235 1061 265 1163 320 1266

167 365 1687 415 1857 425 2028

Liquid

Immersed,
Three

- Phase 15 88 314 110 330 135 345

30 137 534 165 565 210 597

45 180 755 215 802 265 848

75 255 1142 305 1220 365 1297

112.5 350 1597 405 1713 450 1829

150 450 1976 500 2130 525 2284

225 750 2844 820 3080 900 3310

300 910 3644 1000 3951 1100 4260

500 1330 5561 1475 6073 1540 6586

Note: These losses are applicable at 100 percent of nameplate load, and do not include losses from protective
accessories.

It is important to note that Mexican efficiency standards represent an absolute minimum efficiency for each unit that is sold. According to the standards, every transformer must be within the minimum requirement, whereas U.S. DOE requirements provide a tolerance that is applicable to the transformers depending on the number of units built. Therefore, manufacturers selling in Mexico must apply a design margin to account for the statistical variation on loss measurements

. Typically, this margin is around 6 percent of the maximum total losses, which decreases the average losses of the manufacturer’s units by 6 percent compared t o the efficiency requirement.

In practice, however, many distribution transformers sold in Mexico exceed the minimum efficiency requirement

. Unlike the United States, utility services in Mexico are provided by a single, public utility called Comisión Fede ral de Electridad (CFE) . Due to the high loss evaluation formula that CFE uses, many manufacturers produce transformers with losses that are 20 percent or more below the minimum requirement.3

- 24 3.8 TECHNOLOGY ASSESSMEN T

A transformer is a device constructed with two primary components: a magnetically permeable core, and a conductor of a low- resistance material wound around that core

. A distribution transformer's primary function is to change alternating current from one voltage (primary) to a different voltage (se condary)

. It accomplishes this through an alternating magnetic field or "flux" created by the primary winding in the core, which induces the desired voltage in the secondary winding. The change in voltage is determined by the "turns ratio," or relative number of times the primary and secondary windings are wound around the core. If there are twice as many secondary turns as primary turns, the transformer is a step

- up transformer, with a secondary voltage that would be double the primary voltage. Conversely, if the primary has twice as many turns as the secondary, the transformer is called a step -down transformer, with the secondary voltage half as much as the primary voltage. Distribution transformers are always
step

- down transformers.

Transformer losses a re generally small, in the vicinity of a few percent or less of the total power handled by the transformer. There are two main kinds of losses in transformers: no- load (core) losses and load (winding) losses. Higher transformer efficiencies are achieved b y reducing the losses associated with these two assemblies: the core and the windings.

3.8.1 Distribution Transformer Types

In general, there are two primary types of distribution transformer: liquid- immersed and dry- type . Liquid- immersed transformers typical ly use oil as both a coolant (removing heat from the core and coil assembly) and a dielectric medium (preventing electrical arcing across the windings). Liquid-immersed transformers are typically used outdoors because of concerns over oil spills or fire if the oil temperature reaches the flash -point level. In recent decades, newinsulating liquid insulators (e.g., silicone fluid) have been developed which have a higher flashpoint temperature than mineral oil, and transformers with these liquids can be used for indoor applications. However, high initial costs for these less

- flammable, liquid

- immersed transformers, relative to the cost of dry -type units, prevents widespread market adoption.

Dry

- type transformers are air -cooled, fire- resistant devices that do not use oil or other liquid insulating/cooling media . Because air is the basic medium used for insulating and cooling and it is inferior to oil in these functions, dry- type transformers are larger than liquid

- immersed units for the same voltage and/or kVA capacity

. As a result, when operating at the same flux and current densities, the core and coil assembly is larger and hence incurs higher losses . Due to the physics of their construction (including the ability of these units to transfer heat), dry- type u nits have higher losses than liquid- immersed units . However, dry- type transformers are an important part of the transformer market because they can offer safety, environmental, and application advantages.3

- 25 3.8.2 Transformer Efficiency Levels

There are two main t ypes of losses in transformers: no-load (core) losses and load (winding) losses. Core losses are virtually constant with loading, occurring continuously in the core material to keep the transformer energized and ready to provide power at the secondary

ter minals

. Core losses are present even if the load on the transformer is zero . Winding losses occur in the primary and secondary windings around the core, and increase as the square of the load applied to the transformer. Winding losses result primarily from the electrical resistance of the winding material.

Figure 3.8.1 depicts the change in core and coil losses with transformer loading on a 75 kVA dry

- type transformer, built with copper windings and an 80 degree temperature rise. This illustration clearly shows the quadratic growth of the winding losses.

Figure 3.8.1 Transformer Losses Vary with Load (75 Kilovolt- Ampere Dry

- Type)

The equation used to calculate the percent efficiency of a transformer at any loading point is given as follows (IEEE, C57.12.00):

Equation 3.8.1

EE load = � 100 × P load × kVA × 1000

P

load × kVA × 1000 + NL + LL × ( P load ) 2 × T �

where:

EE load = percent efficiency at a given per unit load,

P load = per unit load,
kVA = kVA rating of transformer,

NL = no

- load loss (Watts),

LL = load loss (Watts), and

T = temperature correction factor.3

- 26 As Equation 3.8.1 shows, the efficiency of a transformer is not a static value, but rather will vary depending on the per unit load (P l oad ) applied to the transformer. Using the losses plotted in Figure 3.8.1 , DOE used Equation 3.8.1 to calculate the efficiency of this 75 kVA drytype transformer at each loading point from 0 to 100 percent of nameplate load. The results are
shown in Figure 3.8.2 , which clearly indicates that the efficiency of a transformer is not constant, but rather varies with loading. The highest efficiency occurs at the loading point where core losses are equal t o winding losses.

Figure 3.8.2 Transformer Efficiency Varies with Load

Consequently, any discussion of transformer efficiency must include an assumed loading point. Although DOE assumes a range of loading points in its analysis, (see the energy use and
end -use load characterization sections in chapter 6 of this TSD) the DOE test procedure stipulates that a low -voltage dry-type distribution transformer must be tested at 35% load and
medium- voltage dry

- typ e and liquid- immersed distribution transformers must be tested at 50%
load.

3.8.3 Transformer Losses

This section discusses methods to reduce transformer losses that have been developed over the 125 years of technology evolution. The physical principles of distribution transformer operation are discussed in detail in Chapter 2 of the Determination Analysis of Energy Conservation Standards for Distribution Transformers

. i This section summarizes some of the main technological methods for reducing transformer losses. ix3

- 27 Core losses occur in the core material of the distribution transformer, and are present whenever the transformer is energized – i.e., available to provide or providing load. Core losses are chiefly made up of two components: hysteresis and eddy current losses. Hysteresis losses are caused by the magnetic lag or reluctance of the core molecules to reorient themselves with the 60
hertz alternating magnetic field applied by the primary winding

. Eddy current losses are actual currents induced in the core by the magnetic field, in the same manner that the field induces current in the secondary winding. However, these currents cannot leave the core, and simply circulate within each lamination, eventually becoming heat

. Both hysteresis and eddy current s create heat in the core material.

Measures to reduce core losses include utilizing thinner cold- rolled oriented laminated steel (e.g., M2 or M3) or amorphous material. However, these measures increase the manufacturing cost . In the case of amorphous material, due to a lower maximum core flux density, larges cores must be built, which increases the winding losses.

Winding losses occur in both the primary and secondary windings when a transformer is under load. These losses, the result of electrical resistance in both windings, vary with the square of the load applied to the transformer. As loading increases, winding losses increase and are typically much more significant than core losses at levels higher than 50 percent of the nameplate loading point.

Methods of reducing winding losses tend to cause an increase in no-load losses. One
method is to increase t he cross

- sectional area of the conductor (decreasing current density in the winding material), but that means the core has to be made larger to accommodate the larger volume of the conductor, increasing core losses. Transposition of a multi-strand conducto r can also help reduce winding losses.

Table 3.8.1 was prepared by ORNL. This table summarizes the methods of making a transformer more efficient by reducing the numb er of watts lost in the core (no-load) and winding (load). However, as previously discussed, measures taken to reduce the losses in one
area often increase the losses in another. This table presents those inter- relational issues, as well
as the overall impacts on transformer manufacturing costs.3

- 28 Table 3.8.1 Options and Impacts of Increasing Transformer Efficiency

No

- load

losses Load

losses Cost impact

To decrease no

- load losses

Use lower

- loss core materials Lower No change* Higher Decrease flux density by:

(a) Increasing core cross

- sectional area (CSA) (b) Decreasing volts per turn Lower

Lower Higher Higher Higher Higher Decrease flux path length by decreasing conductor CSA Lower Higher Lower

Use 120  ̊ symmetry in three

- phase cores** Lower No change TBD

To decrease load losses

Use lower

- loss conductor material No change Lower Higher Decrease current density by increasing conductor CSA Higher Lower Higher Decrease current path length by:

(a) Decreasing core CSA (b) Increasing volts per turn Higher Higher Lower

Lower Lower

Lower * Amorphous

- core materials would result in higher load losses because flux density drops, requiring a larger core

volume

. ** Sometimes referred to as a “hexa

- transformer” design.

The methods shown in Table 3.8.1 for making a transformer more efficient are discussed in the screening analysis (Chapter 4) and the engineering analysis (Chapter 5 ). DOE’s analysis of the relationship between cost and efficiency for distribution transformers is presented in Chapter
5.

3.8.4 Core Deactivation

Core deactivation technology employs a system of smaller transformers to replace a single, larger transformer. For example, three transformers sized at 25 kVA and operated in parallel could replace a single 75 kVA transformer. The smaller transformers that compose the system can then be activated and deactivated using core deactivation technology based on the loading demand. Currently, DOE is not considering core deactivation systems in the context of setting standards, but may explore doing so in the future.

Winding losses are proportionally smaller at lower load factors, but for any given current, a smaller transformer will experience greater winding losses than a larger transformer. As a result, those losses may be more than offset by the smaller transformer’s reduced core losses. As loading increases, winding losses become proportionally larger and eventually outweigh the power saved by using the smaller core. At that point, the control unit (which consumes little power itself) switches on an additional transformer, reducing winding losses at the cost of
additional core losses. The control unit knows how efficient each combination of transformers is for any given loading, and is constantly monitoring the unit’s power output so that it will use the optimal number of cores. In theory, there is no limit to the number of transformers that may be paralleled in this sort o f system, but cost considerations would imply an optimal number.

While core deactivation could save energy over a real world loading cycle, those savings might not be represented in the current DOE test procedure. Presently, the test procedure specifies a single loading point of 50 percent for liquid-immersed and medium- voltage dry

- type3

- 29 transformers, and 35 percent for low-voltage dry- type. The real gain in efficiency for this technology is at loading points below the root mean square (RMS) loading specifi ed in the test procedure, where some transformers in the system could be deactivated. At loadings where all transformers are activated, which may be the case at the test procedure loading, the combined core and coil losses of the system of transformers could exceed those of a single, larger transformer. This would result in a lower efficiency for the system of transformers compared to the single, larger transformer.

Therefore, DOE believes core deactivation technology may be at a disadvantage in the
market based on the current test procedure, which specifies a single loading based on the RMS loading in the United States. DOE believes that the core deactivation system would engage all transformers at this loading, resulting in a lower efficiency reading than a standard, single transformer of equivalent size. However, the core deactivation system may save more energy than the standard transformer when all loading points that are experienced in service are considered. This is especially true for applications th at have an average loading below the test procedure loading point.

Based on comments received, DOE has screened core deactivation out of its analysis. DOE acknowledges that it is possible to evaluate core deactivation technology using existing
transformer designs, and that operating a core deactivation system might save energy and lower

LCC . However, DOE does not believe that a bank of transformers used in a core deactivation system is a transformer itself but rather a system made up of individual transfor mers

. DOE has adopted the position that each individual transformer in a core deactivation system must comply with the energy efficiency standards set in this rulemaking

.

3.8.5 Symmetric Core

In a symmetric core configuration, each leg of a three

- phase transfo rmer is identically connected to the other two. It uses a continuously wound core with 120  ̊ radial symmetry, resulting in a triangularly shaped core when viewed from above. In a traditional core, the center leg is magnetically distinguishable from the othe r two because it has a shorter average flux path
to each

. In a symmetric core, however, no leg is magnetically distinguishable from the other two

. Figure 3.8.3 shows the configuration of the symmetric core design. 2

2 Lun dmark, Sonja. Computer Model of Electromagnetic Phenomena in Hexaformer

. 2007. Available at: http://www.hexaformer.com/ExternaDokument/chalmers_report1.pdf

.3

- 30 Figure 3.8.3 Graphic of Symmetric Core Configuration

The symmetric core construction offers several advantages over traditional transformer
cores. These include lowered weight, volume, no-load losses, noise, vibration, stray magnetic fields, inrush current, and power in the third harmonic. Transformers using this core construction can oftentimes use fewer pounds of core steel than a standard core would use to achieve a given efficiency. As a result, total material cost for symmetric core designs is typically lower than that of a standard transformer design. H owever, the advanced manufacturing processes necessary to produce the core increases the cost of labor and overhead for this core configuration. Similarly, the appropriate equipment requires large capital expenditures to manufacture this core type.

Becaus e of zero

- sequence fluxes associated with wye -wye connected transformers, symmetric core designs are best suited to delta

- delta or delta

- wye connections. While traditional cores can circumvent the problem of zero-sequence fluxes by introducing a fourth or fifth unwound leg, core symmetry makes extra legs inherently impractical. Yet another way to mitigate zero -sequence fluxes comes in the form of a tertiary winding, which is delta-connected and has no external connections. This winding is dormant when the transformer’s load is balanced across its phases. Although symmetric core designs may, in theory, be made tolerant of

zero -sequence fluxes by employing this method, it comes at extra cost and complexity.

Using this tertiary winding, DOE believes that symm etric core designs can service nearly all distribution transformer applications in the United States. Most dry

- type transformers have a delta connection and would not require a tertiary winding. Similarly, most liquid- immersed transformers serving the indu strial sector have a delta connection. These market segments could use the symmetric core design without any modification for a tertiary winding. However, in the United States, most utility -operated distribution transformers are wye- wye connected. These

tr ansformers would require the tertiary winding in a symmetric core design.3

- 31 Following the preliminary analysis, DOE did not receive any information regarding symmetric core and was unable to locate a company that had the modeling software to model symmetric core designs . The information DOE was able to collect was not sufficient enough to
conduct a full- scale engineering analysis comparable to the other design types

. Because the data was so limited and DOE did not receive any additional information from manufacturers, DOE did not consider symmetric core designs in this rulemaking.3

- 32 REFERENCES

i ORNL, 1996. Dete rmination Analysis of Energy Conservation Standards for Distribution Transformers , P.R. Barnes, J.W. Van Dyke, B.W. McConnell, S. Das, Oak Ridge National Laboratory, Oak Ridge, Tennessee

. ORNL

6847

. See docket : http://www.regulations.gov/#!docketDetail;D=EERE

- 2006

- STD

- 0099

ii ORNL, 1995

. The Feasibility of Replacing or Upgrading Utility Distribution Transformers During Routine

Maintenance , P.R. Barnes, J.W. Van Dyke, B.W. McC onnell, S.M. Cohn, S.L. Purucker, Oak Ridge National Laboratory, Oak Ridge, Tennessee, ORNL

- 6804/R1

. See docket : http://www.regulations.gov/#!docketDetail;D=EERE

- 2006

- STD

- 0099

iii IEEE, 2001

. IEEE PC57.12.33/D8 Draft Guide for Distribution Transformer Loss Evaluation, prepared by the Working Group for the Guide for Distribution Transformer Loss Evaluation of the Distribution Sub

- committee of the IEEE Transformers Committee, October 2001.

iv NEMA, 1996

. NEMA Standards Publication No. TP 1: Guide for Determining Energy Efficiency for Distribution Transformers , National Electrical Manufacturers Association, Rosslyn, VA.

v NEMA, 2002. NEMA Standards Publication TP 1

- 2002: Guide for Determining Energy Efficiency for Distribution Transformers , National Electrical Manufacturers Association, Rosslyn, VA.

vi Seattle City Light, Energy Smart Services, < http://www.cityofseattle.net/light/conserve/business/cv5_fi.htm >, viewed July 2005.

vii Gomez, 2001

. Jose Antonio Gomez, P.E., Asociacion de Normalizacion y Certificacion (ANCE, Association of
Standards and Certificati on)

. Mexico City, Mexico. personal communication, June 17, 2001.; Lara, 2001. Ing. Rene Perez Lara, Dirección General de Gas LP y de Instalaciones Eléctricas, Secretaría de Energía

. Mexico City, Mexico

. Personal communication, May, 2001

. (Gas and Electric Installations Division, Department of Energy).

viii Manifestación de Impacto Regulatorio, Proyecto de Norma Oficial Mexicana NOM

- 002

- SEDE

- 1997

. Secretaría de Energía, Mexico City, Mexico, 1997 (Regulatory Impact Analysis, Proposed Official Mexican Standard N OM

002

- SEDE

- 1997), Department of Energy, Mexico City, Mexico.

ix Energy Efficient Transformers, Barry W. Kennedy, McGraw

- Hill Publishing, New York, NY

. Control of Transformer Losses in Canada , D.A. Wiegand, IEEE Journal, 1994

. Determination Analysis of Energy Conservation Standards for Distribution Transformers , P.R. Barnes, J.W. Van Dyke, B.W. McConnell, S. Das, Oak Ridge National Laboratory, Oak Ride, Tennessee

. ORNL

- 6847

. See docket : http://www.regulations.gov/#!docketDetail;D=EERE

- 2006

- STD

- 0099