[Federal Register Volume 86, Number 175 (Tuesday, September 14, 2021)]
[Rules and Regulations]
[Pages 51230-51255]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-19366]



[[Page 51229]]

Vol. 86

Tuesday,

No. 175

September 14, 2021

Part II





 Department of Energy





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10 CFR Part 431





Energy Conservation Program: Test Procedure for Distribution 
Transformers; Final Rule

  Federal Register / Vol. 86 , No. 175 / Tuesday, September 14, 2021 / 
Rules and Regulations  

[[Page 51230]]


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DEPARTMENT OF ENERGY

10 CFR Part 431

[EERE-2017-BT-TP-0055]
RIN 1904-AE19


Energy Conservation Program: Test Procedure for Distribution 
Transformers

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of 
Energy.

ACTION: Final rule.

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SUMMARY: The U.S. Department of Energy (``DOE'') is amending the test 
procedure for distribution transformers to revise and add definitions 
of certain terms, update provisions based on the latest versions of 
relevant industry testing standards, and to specify the basis for 
voluntary representations at additional per-unit loads and additional 
reference temperatures. The updates in this final rule will not 
significantly change the test procedure.

DATES: The effective date of this rule is October 14, 2021. The final 
rule changes will be mandatory for product testing starting March 14, 
2022.

ADDRESSES: The docket, which includes Federal Register notices, 
comments, and other supporting documents/materials, is available for 
review at www.regulations.gov. All documents in the docket are listed 
in the www.regulations.gov index. However, some documents listed in the 
index, such as those containing information that is exempt from public 
disclosure, may not be publicly available.
    A link to the docket web page can be found at www.regulations.gov/docket/EERE-2017-BT-TP-0055. The docket web page contains instructions 
on how to access all documents, including public comments, in the 
docket.
    For further information on how to review the docket contact the 
Appliance and Equipment Standards Program staff at (202) 287-1445 or by 
email: [email protected].

FOR FURTHER INFORMATION CONTACT: 
    Mr. Jeremy Dommu, U.S. Department of Energy, Office of Energy 
Efficiency and Renewable Energy, Building Technologies Office, EE-2J, 
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: 
(202) 586-9870. Email: [email protected].
    Mr. Matthew Ring, U.S. Department of Energy, Office of the General 
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. 
Telephone: (202) 586-2555. Email: [email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Authority and Background
    A. Authority
    B. Background
II. Synopsis of the Final Rule
III. Discussion
    A. Scope of Applicability
    B. Updates to Industry Testing Standards
    1. Recission of NEMA TP 2
    2. Updates to IEEE Standards
    C. Definitions
    1. Rectifier Transformers and Drive Transformers
    2. New Definitions
    3. Updated Definitions
    D. Per-Unit Load Testing Requirements
    1. Multiple-PUL Weighted-Average Efficiency Metric
    2. Single-PUL Efficiency Metric
    3. Voluntary Representations of Efficiency at Additional PULs
    E. Multiple Voltage Capability
    F. Other Test Procedure Topics
    1. Per-Unit Load Specification
    2. Reference Temperature Specification
    3. Measurement Location
    4. Specification for Stabilization of Current and Voltage
    5. Ambient Temperature Tolerances
    6. Harmonic Current
    7. Other Editorial Revisions
    G. Effective and Compliance Dates
    H. Test Procedure Costs
IV. Procedural Issues and Regulatory Review
    A. Review Under Executive Order 12866
    B. Review Under the Regulatory Flexibility Act
    C. Review Under the Paperwork Reduction Act of 1995
    D. Review Under the National Environmental Policy Act of 1969
    E. Review Under Executive Order 13132
    F. Review Under Executive Order 12988
    G. Review Under the Unfunded Mandates Reform Act of 1995
    H. Review Under the Treasury and General Government 
Appropriations Act, 1999
    I. Review Under Executive Order 12630
    J. Review Under Treasury and General Government Appropriations 
Act, 2001
    K. Review Under Executive Order 13211
    L. Review Under Section 32 of the Federal Energy Administration 
Act of 1974
    M. Congressional Notification
V. Approval of the Office of the Secretary

I. Authority and Background

    DOE is authorized to establish and amend energy conservation 
standards and test procedures for certain industrial equipment, 
including distribution transformers. The current DOE test procedure for 
distribution transformers appear at title 10 of the Code of Federal 
Regulations (``CFR'') 431.193 and appendix A to subpart K of 10 CFR 
part 431 (``appendix A'') respectively. The current energy conservation 
standards for distribution transformers appear at 10 CFR 431.196. The 
following sections discuss DOE's authority to establish test procedures 
for distribution transformers and relevant background information 
regarding DOE's consideration of test procedures for this equipment.

A. Authority

    The Energy Policy and Conservation Act, as amended (``EPCA''),\1\ 
authorizes DOE to regulate the energy efficiency of a number of 
consumer products and certain industrial equipment. (42 U.S.C. 6291-
6317, as codified) Title III, Part B \2\ of EPCA established the Energy 
Conservation Program for Consumer Products Other Than Automobiles (42 
U.S.C. 6291-6309, as codified), which sets forth a variety of 
provisions designed to improve energy efficiency of specified consumer 
products. Title III, Part C \3\ of EPCA, added by the National Energy 
Conservation Policy Act, Public Law 95-619, Title IV, section 441(a), 
established the Energy Conservation Program for Certain Industrial 
Equipment (42 U.S.C. 6311-6317, as codified), which sets forth a 
variety of provisions designed to improve energy efficiency of certain 
industrial equipment. This equipment includes distribution 
transformers, the subject of this final rule. (42 U.S.C. 6317(a))
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    \1\ All references to EPCA in this document refer to the statute 
as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 
27, 2020).
    \2\ For editorial reasons, upon codification in the U.S. Code, 
Part B was redesignated Part A.
    \3\ For editorial reasons, upon codification in the U.S. Code, 
Part C was redesignated Part A-1.
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    The energy conservation program under EPCA consists essentially of 
four parts: (1) Testing, (2) labeling, (3) Federal energy conservation 
standards, and (4) certification and enforcement procedures. Relevant 
provisions of EPCA for distribution transformers specifically include 
definitions (42 U.S.C. 6291; 42 U.S.C. 6311), test procedures (42 
U.S.C. 6293; 42 U.S.C. 6317), labeling provisions (42 U.S.C. 6294; 42 
U.S.C. 6315), energy conservation standards (42 U.S.C. 6295; 42 U.S.C. 
6317), and the authority to require information and reports from 
manufacturers (42 U.S.C. 6296; 42 U.S.C. 6316).
    The Federal testing requirements consist of test procedures that 
manufacturers of covered products and covered equipment must use as the 
basis for: (1) Certifying to DOE that their products or equipment 
comply with the applicable energy conservation standards adopted 
pursuant to EPCA (42 U.S.C. 6295(s); 42 U.S.C. 6316(a)), and (2) making 
representations about the efficiency of those covered products or

[[Page 51231]]

covered equipment (42 U.S.C. 6293(c); 42 U.S.C. 6314(d)). Similarly, 
DOE must use these test procedures to determine whether the products or 
equipment comply with relevant standards promulgated under EPCA. (42 
U.S.C. 6295(s); 42 U.S.C. 6316(a))
    Federal energy efficiency requirements for covered products and 
covered equipment established under EPCA generally supersede State laws 
and regulations concerning energy conservation testing, labeling, and 
standards. (42 U.S.C. 6297; 42 U.S.C. 6316(a) and (b)) DOE may, 
however, grant waivers of Federal preemption for particular State laws 
or regulations, in accordance with the procedures and other provisions 
of EPCA. (42 U.S.C. 6297(d); 42 U.S.C. 6316(b)(2)(D))
    EPCA set forth the criteria and procedures DOE must follow when 
prescribing or amending test procedures for covered products \4\ and 
covered equipment, respectively. EPCA requires that any test procedures 
prescribed or amended under these sections be reasonably designed to 
produce test results which measure energy efficiency, energy use or 
estimated annual operating cost of a covered product during a 
representative average use cycle or period of use and not be unduly 
burdensome to conduct. (42 U.S.C. 6293(b)(3); see also 42 U.S.C. 
6314(a)(2))
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    \4\ DOE generally refers to distribution transformers as covered 
equipment. However, to the extent that DOE is discussing provisions 
of Part B of EPCA that are applicable to distribution transformers, 
``covered product'' is used.
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    EPCA also requires that, at least once every 7 years, DOE evaluate 
test procedures for each type of covered product and covered equipment, 
including distribution transformers, to determine whether amended test 
procedures would more accurately or fully comply with the requirements 
for the test procedures to not be unduly burdensome to conduct and be 
reasonably designed to produce test results that reflect energy 
efficiency, energy use, and estimated operating costs during a 
representative average use cycle. (42 U.S.C. 6293(b)(1)(A); see also 42 
U.S.C. 6314(a)(1))
    If the Secretary determines, on her own behalf or in response to a 
petition by any interested person, that a test procedure should be 
prescribed or amended, the Secretary shall promptly publish in the 
Federal Register proposed test procedures and afford interested persons 
an opportunity to present oral and written data, views, and arguments 
with respect to such procedures. The comment period on a proposed rule 
to amend a test procedure shall be at least 60 days and may not exceed 
270 days. In prescribing or amending a test procedure, the Secretary 
shall take into account such information as the Secretary determines 
relevant to such procedure, including technological developments 
relating to energy use or energy efficiency of the type (or class) of 
covered products or covered equipment involved. (42 U.S.C. 6293(b)(2)) 
If DOE determines that test procedure revisions are not appropriate, 
DOE must publish its determination not to amend the test procedures. 
DOE is publishing this final rule in satisfaction of the 7-year review 
requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A); see also 42 
U.S.C. 6314(b)(1))
    DOE is issuing this final rule to amend the test procedure for 
distribution transformers in accordance with its statutory obligations.

B. Background

    With respect to distribution transformers, EPCA states that the 
test procedures for distribution transformers shall be based on the 
``Standard Test Method for Measuring the Energy Consumption of 
Distribution Transformers'' prescribed by the National Electrical 
Manufacturers Association (NEMA TP 2-1998). (42 U.S.C. 6293(b)(10)(A)) 
Further, DOE may review and revise the DOE test procedure. (42 U.S.C. 
6293(b)(10)(B))
    Consistent with the requirements in EPCA, DOE published a final 
rule on April 27, 2006, that established the test procedure for 
distribution transformers based on the test methods in NEMA TP 2-1998 
and the test methods contained in the Institute of Electrical and 
Electronics Engineers (``IEEE'') Standards C57.12.90-1999 and 
C57.12.91-2001. 71 FR 24972, 24974. See 71 FR 24972 (April 27, 2006) 
(``April 2006 Final Rule'').\5\
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    \5\ DOE published a technical correction to the April 2006 Final 
Rule to correct typographical errors. 71 FR 60662 (Oct. 16, 2006).
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    In a final rule published on April 18, 2013, amending the energy 
conservation energy conservation standards (``ECS'') for distribution 
transformers (``April 2013 ECS Final Rule''), DOE determined that the 
test procedure did not require amendment at that time, concluding that 
the test procedure as established in the April 2006 Final Rule was 
reasonably designed to produce test results that reflect energy 
efficiency and energy use, as required by 42 U.S.C. 6314(a)(2). 78 FR 
23336, 23347-23348. The current test procedures for distribution 
transformers may be found in 10 CFR 431.193 and 10 CFR part 431, 
subpart K, appendix A.
    On September 22, 2017, DOE published a request for information 
(``RFI'') to collect data and information to inform its consideration 
of whether to amend DOE's test procedure for distribution transformers 
(``September 2017 RFI''). 82 FR 44347. After consideration of comments 
received in response to the September 2017 RFI, DOE published a notice 
of proposed rulemaking (``NOPR'') on May 10, 2019 (``May 2019 NOPR''), 
presenting DOE's proposals to amend the distribution transformer test 
procedure. 84 FR 20704.
    DOE received comments in response to the May 2019 NOPR from the 
interested parties listed in Table I.1.

                        Table I.1--Written Comments Received in Response to May 2019 NOPR
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                                         Reference in this
          Organization(s) *                  document                          Organization type
----------------------------------------------------------------------------------------------------------------
Appliance Standards Awareness         Efficiency Advocates..  Efficiency Organizations.
 Project, American Council for an
 Energy-Efficient Economy, Natural
 Resources Defense Council.
Cargill.............................  Cargill...............  Insulating Liquid Manufacturer.
Copper Development Association......  CDA...................  Trade Association.
Howard Industries Inc...............  Howard................  Manufacturer.
HVOLT Inc...........................  HVOLT.................  Industry Consultant.
National Electrical Manufacturers     NEMA..................  Trade Association.
 Association.
Pacific Gas & Electric Company......  PG&E..................  Electrical Utility.
----------------------------------------------------------------------------------------------------------------
* This list includes only those commenters that provided comments relevant to the May 2019 NOPR.


[[Page 51232]]

    A parenthetical reference at the end of a comment quotation or 
paraphrase provides the location of the item in the public record.\6\
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    \6\ The parenthetical reference provides a reference for 
information located in the docket of DOE's rulemaking to develop 
test procedures for distribution transformers. (Docket No. EERE-
2017-BT-STD-0055, which is maintained at www.regulations.gov). The 
references are arranged as follows: (commenter name, comment docket 
ID number, page of that document).
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II. Synopsis of the Final Rule

    In this final rule, DOE amends 10 CFR 431.192, 431.193, 431.196, 
and appendix A as follows:
    (1) Explicitly specify that the test procedure is applicable only 
to distribution transformers that are subject to energy conservation 
standards,
    (2) Include new definitions for ``per-unit load,'' ``terminal'' and 
``auxiliary device,'' and updated definitions for ``low-voltage dry-
type distribution transformer'' and ``reference temperature,''
    (3) Reflect certain revisions from the latest version of the IEEE 
testing standards on which the DOE test procedure is based,
    (4) Incorporate other clarifying revisions based on review of the 
DOE test procedure,
    (5) Specify use of existing test procedure provisions for voluntary 
(optional) representations at additional per-unit loads (``PULs'') and 
reference temperatures, and
    (6) Centralize the PUL and reference temperature specifications for 
certification to energy conservation standards and for voluntary 
representations.
    The adopted amendments are summarized in Table II.1 compared to the 
test procedure provision prior to the amendment, as well as the reason 
for the adopted change. Table II.2 compares the changes adopted in this 
final rule to the proposal of the May 2019 NOPR.

      Table II.1--Summary of Changes in the Amended Test Procedure
------------------------------------------------------------------------
                                  Amended test
 DOE test procedure prior to   procedure (adopted        Attribution
          amendment            by this final rule)
------------------------------------------------------------------------
Current test procedure does   States explicitly     Clarification added
 not specify scope.            that the scope of     by DOE.
                               the test procedure
                               is limited to the
                               scope of equipment
                               subject to the
                               energy conservation
                               standards.
PUL is referred to as         Consolidates all      Improves consistency
 ``percent load,'' ``percent   terms to only ``per-  and readability of
 of nameplate-rated load,''    unit load''.          test procedure.
 ``percent of the rated
 load,'' or ``per unit load
 level''.
Does not define ``Per-unit    Adds new definitions  Reflects industry
 load,'' ``Terminal'' and      for ``Per-unit        testing standard
 ``Auxiliary device,'' which   load,''               definition
 are used in the current       ``Terminal,'' and     (terminal) and
 test procedure (TP).          ``Auxiliary           clarification added
                               device''.             by DOE (PUL and
                                                     auxiliary device).
Includes definition of ``Low- Updates definition    Aligns with industry
 Voltage Dry-Type              of ``Low-Voltage      definition.
 Distribution Transformer''.   Dry-Type
                               Distribution
                               Transformer''.
Test procedure provisions     Updates provisions    Reflects industry
 are based on four IEEE        based on the latest   testing standard
 testing standards, which      version of the four   updates.
 contain general               IEEE testing
 requirements and methods      standards:
 for performing tests:        C57.12.00-2015......
C57.12.00-2000.               C57.12.01-2020......
C57.12.01-1998.               C57.12.90-2015......
C57.12.90-1999.               C57.12.91-2020......
C57.12.91-2001.
Requires reporting            States explicitly     Update to reflect
 performance at the rated      that all testing      industry testing
 frequency; however, the       under the DOE test    standards.
 rated frequency is not        procedure is to
 explicitly defined.           occur only at 60 Hz.
Requires determining winding  Specifies that the    Update to reflect
 resistance but does not       polarity of the       industry testing
 specify whether the           core magnetization    standards.
 polarity of the core          be kept constant
 magnetization should be       during all
 kept constant as              resistance readings.
 measurements are made.
Requires the measurement of   Specifies explicitly  Update to reflect
 load and no-load loss,        that load and no-     industry testing
 without explicitly            load loss             standards.
 specifying the connection     measurements are
 locations for measurements.   required to be
                               taken only at the
                               transformer
                               terminals.
Testing with a sinusoidal     Specifies that all    Update to reflect
 waveform explicitly           transformers must     industry practice.
 specified only for            be tested using a
 transformers designed for     sinusoidal waveform
 harmonic currents.            (not just those
                               designed for
                               harmonic current).
Energy conservation           Permits voluntary     Response to industry
 standards require that        representations of    comment.
 efficiency be determined at   efficiency, load
 a single PUL of 50 percent    loss and no-load
 for both liquid-immersed      loss at additional
 and medium-voltage dry type   PULs and/or
 (MVDT) distribution           reference
 transformers, and at 35       temperature, using
 percent for low-voltage dry-  the DOE test
 type (LVDT) distribution      procedure. (Does
 transformers.                 not require
                               certification to
                               DOE of any
                               voluntary
                               representations.)
Specifies PUL and reference   Centralizes the PUL   Improves readability
 temperature specifications    and reference         of test procedure.
 for certification to energy   temperature
 conservation standards in     specifications,
 multiple locations            both for the
 throughout appendix A.        certification to
                               energy conservation
                               standards and for
                               use with a
                               voluntary
                               representation.
------------------------------------------------------------------------


[[Page 51233]]


  Table II.2--Summary of Changes--Final Rule Relative to May 2019 NOPR
------------------------------------------------------------------------
 DOE test procedure prior to
          amendment               NOPR proposal          Final rule
------------------------------------------------------------------------
Current test procedure does   States explicitly     Adopts modification
 not specify scope.            that the scope of     as proposed.
                               the test procedure
                               is limited to the
                               scope of equipment
                               subject to the
                               energy conservation
                               standards.
PUL is referred to as         Consolidates all      Adopts modification
 ``percent load,'' ``percent   terms to only ``per-  as proposed.
 of nameplate-rated load,''    unit load.''.
 ``percent of the rated
 load,'' or ``per unit load
 level''.
Does not define ``Per-unit    Adds new definitions  Adopts modification
 load,'' ``Terminal'' and      for ``Per-unit        as proposed.
 ``Auxiliary device,'' which   load,''
 are used in the current TP.   ``Terminal,'' and
                               ``Auxiliary
                               device.''.
Aligns definition of ``Low-   Proposes updated      Slight change from
 Voltage Dry-Type              definition of ``Low-  NOPR to align with
 Distribution Transformer''    Voltage Dry-Type      industry
 with industry definition.     Distribution          definition.
                               Transformer.''.
Test procedure provisions     Updates provisions    Adopts modifications
 are based on four IEEE        based on the latest   as proposed. Note
 testing standards, which      version of the four   that after NOPR
 contain general               IEEE testing          publication, IEEE
 requirements and methods      standards:            updated C57.12.91-
 for performing tests:        C57.12.00-2015......   2011 and C57.12.01-
C57.12.00-2000.               C57.12.01-2015......   2015 to C57.12.91-
C57.12.01-1998.               C57.12.90-2015......   2020 and C57.12.01-
C57.12.90-1999.               C57.12.91-2011......   2020. The relevant
C57.12.91-2001.                                      provisions of
                                                     C57.12.91-2020 and
                                                     C57.12.01-2020 and
                                                     the other two
                                                     testing standards
                                                     are unchanged.
Automatic Recording of Data   Requires automatic    NOPR proposal not
 Not Required.                 recording of data,    adopted in this
                               as required in IEEE   final rule.
                               C57.12.90-2015 and
                               IEEE C57.12.91-
                               2011, using a
                               digital data
                               acquisition system.
                               (Appendix A,
                               section 4.4.2(b)).
Requires reporting            States explicitly     Adopted no-load loss
 performance at the rated      that all testing      test as proposed.
 frequency; however, the       under the DOE test    NOPR proposal not
 rated frequency is not        procedure is to       adopted for
 explicitly defined.           occur only at 60 Hz   resistance
                               for resistance        measurements.
                               measurement and no-
                               load loss test.
Requires determining winding  Specifies that the    Adopts modification
 resistance but does not       polarity of the       as proposed.
 specify whether the           core magnetization
 polarity of the core          be kept constant
 magnetization should be       during all
 kept constant as              resistance readings.
 measurements are made.
Requires the measurement of   Specifies explicitly  Adopts modification
 load and no-load loss,        that load and no-     as proposed.
 without explicitly            load loss
 specifying the connection     measurements are
 locations for measurements.   required to be
                               taken only at the
                               transformer
                               terminals.
Testing with a sinusoidal     Specifies that all    Adopts modification
 waveform explicitly           transformers must     as proposed.
 specified only for            be tested using a
 transformers designed for     sinusoidal waveform
 harmonic currents.            (not just those
                               designed for
                               harmonic current).
Energy conservation           Permits voluntary     Adopts modification
 standards require that        representations of    as proposed.
 efficiency be determined at   efficiency, load
 a single PUL of 50 percent    loss and no-load
 for both liquid-immersed      loss at additional
 and MVDT distribution         PULs and/or
 transformers, and at 35       reference
 percent for LVDT              temperature, using
 distribution transformers.    the DOE test
                               procedure. (Does
                               not require
                               certification to
                               DOE of any
                               voluntary
                               representations.)
Specifies PUL and reference   Centralizes the PUL   No change from NOPR.
 temperature specifications    and reference
 for certification to energy   temperature
 conservation standards in     specifications,
 multiple locations            both for the
 throughout appendix A.        certification to
                               energy conservation
                               standards and for
                               use with a
                               voluntary
                               representation.
------------------------------------------------------------------------

    DOE has determined that the amendments described in section III and 
adopted in this document will not alter the measured efficiency of 
distribution transformers or require retesting or recertification 
solely as a result of DOE's adoption of the amendments to the test 
procedure. Additionally, DOE has determined that the amendments will 
not increase the cost of testing. Discussion of DOE's actions are 
addressed in detail in section III of this document.
    The effective date for the amended test procedure adopted in this 
final rule is 30 days after publication of this document in the Federal 
Register. Representations of energy use or energy efficiency must be 
based on testing in accordance with the amended test procedure 
beginning 180 days after the publication of this final rule.

III. Discussion

A. Scope of Applicability

    The applicability of the test procedure is provided in 10 CFR 
431.193, which states that ``the test procedures for measuring the 
energy efficiency of distribution transformers for purposes of EPCA are 
specified in appendix A to this subpart.'' DOE has established energy 
conservation standards for low-voltage dry-type (``LVDT'') distribution 
transformers, liquid-immersed distribution transformers, and medium-
voltage dry type (``MVDT'') distribution transformers at 10 CFR 
431.196. In the May 2019 NOPR, DOE proposed to state explicitly that 
the scope of the test procedure is limited to the scope of the 
distribution transformers that are subject to energy conservation 
standards. 84 FR 20704, 20706. DOE did not receive any comments 
regarding this proposal. DOE is modifying text in 10 CFR 431.193 
regarding the scope of the test procedure as proposed.

[[Page 51234]]

B. Updates to Industry Testing Standards

    The current DOE test procedure for distribution transformers is 
based on provisions from the following industry testing standards (See 
71 FR 24972, 24982 (April 27, 2006)):
 NEMA TP 2-1998, ``Standard Test Method for Measuring the 
Energy Consumption of Distribution Transformers'' (NEMA TP 2-1998)
 IEEE C57.12.90-1999, ``IEEE Standard Test Code for Liquid-
Immersed Distribution, Power and Regulating Transformers and IEEE Guide 
for Short Circuit Testing of Distribution and Power Transformers''
 IEEE C57.12.91-2001, ``IEEE Standard Test Code for Dry-Type 
Distribution and Power Transformers''
 IEEE C57.12.00-2000, ``IEEE Standard General Requirements for 
Liquid-Immersed Distribution, Power and Regulating Transformers''
 IEEE C57.12.01-1998, ``IEEE Standard General Requirements for 
Dry-Type Distribution and Power Transformers Including those with Solid 
Cast and/or Resin Encapsulated Windings''
    In addition, the DOE test procedure is also based on provisions in 
NEMA TP 2-2005,\7\ which in turn reference the aforementioned IEEE 
testing standards.\8\ DOE determined that basing the procedure on 
multiple industry testing standards, as opposed to adopting an industry 
test procedure (or procedures) without modification, was necessary to 
provide the detail and accuracy required for the Federal test 
procedure, with the additional benefit of providing manufacturers the 
Federal test procedure in a single reference. 71 FR 24972, 24982 (April 
27, 2006).
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    \7\ Standard Test Method for Measuring the Energy Consumption of 
Distribution Transformers, available at: nema.org/Standards/Pages/Standard-Test-Method-for-Measuring-the-Energy-Consumption-of-Distribution-Transformers.aspx.
    \8\ Prior to the April 2006 Final Rule, NEMA provided the 
Department with its revised test procedure document (i.e., update to 
NEMA TP 2-1998), TP 2-2005. The Department treated this submission 
as a comment on DOE's rulemaking to establish a distribution 
transformer test procedure. 71 FR 24972, 24973. As such, the DOE 
test procedure incorporated a number of the changes that this 
revision made to the rule language and addressed the differences 
between the DOE test procedure and NEMA TP 2-2005. Id.
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    DOE previously sought comment on the benefits and burdens of 
adopting industry testing standards without modification. 82 FR 44347, 
44351 (Sep. 22, 2017). NEMA commented generally that there is benefit 
but that DOE should limit the reference to the measurement of losses 
and retain DOE's existing calculation for efficiency. (NEMA, Docket No. 
EERE-2017-BT-TP-0055-0014 p. 9) DOE stated in the May 2019 NOPR that 
the current test procedure is already based on industry testing 
standards and that if DOE were to adopt an industry testing standard 
without modification, the resulting changes could require manufacturers 
to retest and recertify, because such an incorporation by reference 
would require updating a majority of the current test procedure. 84 FR 
20704, 20710. For these reasons, DOE did not propose to incorporate 
industry testing standard into its test procedure for distribution 
transformers. Id.
    NEMA further commented that while the existing test procedure is 
adequate, for high volume units the test procedures found in IEEE 
C57.12.90-2015 and IEEE C.57.12.91-2011 are less burdensome and 
recommended that DOE allow them as equivalent alternatives for the 
purposes of testing and certification. (NEMA, No. 30 at p. 5) As 
discussed, DOE's test procedure is partially based on the IEEE testing 
standards, and there are similarities between the DOE test procedure 
and the IEEE testing standards. There are also minor differences 
between the DOE test procedure and the IEEE testing standards, such as 
DOE's requirement to test multiple-voltage-capable distribution 
transformers in the highest losses configuration (appendix A, sections 
4.5.1(b) and 5.0), as discussed in section III.E. Testing according to 
the IEEE test procedures without modification could result in 
distribution transformers being tested at different conditions 
depending on the method used. Therefore, DOE is not permitting use of 
IEEE testing standards as equivalent alternatives. DOE may consider 
referencing sections of the IEEE test procedures as equivalent in the 
future if there is sufficient data and information that doing so would 
result in equivalent measured efficiency values with the DOE test 
procedure.
1. Recission of NEMA TP 2
    As discussed, EPCA requires that DOE base the test procedure on 
NEMA TP 2-1998. (42 U.S.C. 6293(b)(10)(A)) Also as discussed, the DOE 
test procedure is based on (but does not incorporate by reference 
directly) NEMA TP 2-1998, NEMA TP 2-2005, as well as four IEEE 
standards that are referenced in NEMA TP 2-2005, i.e., IEEE.C57.12.00, 
IEEE C57.12.01, IEEE C57.12.90 and IEEE C57.12.91. See 71 FR 24972, 
24982 (April 27, 2006). As discussed in the following section, updates 
have been made to the IEEE testing standards.
    Since publication of the April 2006 Final Rule, NEMA TP 2-2005 has 
been rescinded and superseded in industry by the IEEE standards. DOE 
has evaluated the provisions in the Federal test procedure that are 
based on NEMA TP 2 and, as discussed in the May 2019 NOPR, has 
determined that these provisions remain appropriate for testing 
distribution transformers. DOE did not receive any comments on these 
provisions in the May 2019 NOPR and therefore maintained them in this 
final rule.
2. Updates to IEEE Standards
a. Background
    As discussed in section III.B, the DOE test procedure mirrors four 
widely used IEEE testing standards. Since the April 2006 Final Rule, 
all of the four IEEE standards have been updated.
    In the May 2019 NOPR, DOE proposed updating certain Federal test 
procedure provisions to reflect the following updated versions of the 
relevant IEEE testing standards: IEEE C57.12.90-2015, IEEE C57.12.91-
2011, IEEE C57.12.00-2015, and IEEE C57.12.01-2015. Since publication 
of the May 2019 NOPR, IEEE issued a further update to standard IEEE 
C57.12.91 (IEEE C57.12.91-2020) and IEEE C57.12.01-2015 (IEEE 
C57.12.01-2020). Table III.1 provides a list of old and new versions of 
each of these IEEE testing standards.

[[Page 51235]]



    Table III.1--IEEE Industry Testing Standards Versions and Summary
------------------------------------------------------------------------
                       Version on which
                           DOE test        Most recent
    IEEE standard       procedure prior   IEEE revision      Content
                        to amendment is  version (year)
                         based (year)
------------------------------------------------------------------------
C57.12.00............              2000            2015  General
                                                          electrical and
                                                          mechanical
                                                          requirements
                                                          for liquid-
                                                          immersed
                                                          distribution
                                                          transformers.
C57.12.01............              1998            2020  General
                                                          electrical and
                                                          mechanical
                                                          requirements
                                                          for dry-type
                                                          distribution
                                                          transformers.
C57.12.90............              1999            2015  Methods for
                                                          performing
                                                          tests
                                                          specified in
                                                          C57.12.00 and
                                                          others for
                                                          liquid-
                                                          immersed
                                                          distribution
                                                          transformers.
C57.12.91............              2001            2020  Methods for
                                                          performing
                                                          tests
                                                          specified in
                                                          C57.12.01 and
                                                          others for dry-
                                                          type
                                                          distribution
                                                          transformers.
------------------------------------------------------------------------

b. General Updates
    For the May 2019 NOPR, DOE reviewed the then most current editions 
of the relevant IEEE testing standards to determine whether any of the 
updates from the previously considered versions warranted proposed 
amendments to the DOE test procedure. The four IEEE testing standards 
are not relevant to the DOE test procedure in their entirety, as they 
include specifications and test methods beyond those required to 
measure efficiency, such as test methods for polarity, phase-relation, 
dielectric, and audible sound-level. DOE performed the review as 
follows:
    (1) DOE identified the sections of the IEEE testing standards that 
form the basis of the DOE test procedure,
    (2) DOE compared those sections between the old and the then 
current versions of the IEEE testing standards, and
    (3) DOE initially determined which of the changes were editorial 
versus which represented potential substantive improvements to the test 
method.
    In IEEE C57.12.90-2015 and IEEE C57.12.91-2011, sections 5, 8, and 
9 provide the resistance measurements, the no-load loss test, and the 
load loss test, respectively, which provide the basis for the DOE test 
procedure. In general, DOE did not identify major changes in sections 
5, 8, and 9 between 1999 and 2015 editions of IEEE C57.12.90-2015, or 
between the 2001 and 2011 editions of IEEE C57.12.91-2011. Since the 
May 2019 NOPR, DOE has reviewed the updated IEEE C57.12.91-2020 test 
procedure and concluded that there were no substantive differences 
between the relevant provisions in the 2011 and 2020 versions.
    The IEEE C57.12.00 and IEEE C57.12.01 testing standards include 
general electrical and mechanical requirements for the test methods for 
liquid-immersed and dry-type distribution transformers, in IEEE 
C57.12.90 and IEEE C57.12.91, respectively. In IEEE C57.12.00 and IEEE 
C57.12.01, section 9 and section 5, respectively, provide accuracy 
requirements for conducting the resistance measurements, the no-load 
loss test, and the load loss test. The primary change DOE identified in 
the accuracy requirements between the 2000 and 1998 standards and the 
2015 standards was a slight relaxation of the temperature system 
accuracy requirement, from 1 [deg]C in the older versions 
to 1.5 [deg]C for liquid-immersed distribution transformers 
and 2 [deg]C for medium-voltage dry-type distribution 
transformers and low-voltage dry-type distribution transformers. Since 
the May 2019 NOPR, DOE has reviewed the updated IEEE C57.12.91-2020 
test procedure and concluded that there were no substantive differences 
between the relevant provisions in the 2015 and 2020 versions.
    In the May 2019 NOPR, DOE proposed a series of updates based on the 
then most recent updates to the relevant IEEE testing standards. 84 FR 
20704, 20711. DOE stated the proposed updates reflect current industry 
practice, and as such, would not change current measured values. Id. 
DOE further stated that providing additional specificity consistent 
with the updates would improve the repeatability of the test procedure. 
Id. DOE requested comment on the proposed changes to reflect the 
updates to the relevant IEEE testing standards. Id.
    DOE received comments from Howard, NEMA, CDA, and HVOLT agreeing 
that the proposed updates are already industry practice and would not 
change any values or increase testing costs for manufacturers. (Howard, 
No. 32 at p.1; NEMA, No. 20 at p. 3; CDA, No. 29 at p. 2; HVOLT, No. 27 
at p. 91)
    Based on its review of the updates to the relevant IEEE testing 
standards and following consideration of the comments, DOE is adopting 
the proposed updates and clarifications, with two exceptions, discussed 
below.
c. Automatic Recording of Data
    In the May 2019 NOPR, DOE proposed to require automatic recording 
of data using a digital data acquisition system at appendix A, section 
4.4.2(b), in an attempt to align with industry standards. 84 FR 20704, 
20711. NEMA commented that the proposed requirement to automatically 
record data using a digital data acquisition system is listed in IEEE 
C57.12.90-2015 and C57.12.91-2020 for making resistance measurements by 
the voltmeter-ammeter method, and not for the no-load loss measurements 
as was proposed in the May 2019 NOPR. (NEMA, No. 30 at p. 3) NEMA 
commented that requiring automatic recording of data using a digital 
data acquisition system for the no-load losses could require some labs 
to upgrade test equipment, as not all power analyzers have this 
capability. Id.
    DOE acknowledges that IEEE C57.12.90-2015 and C57.12.91-2020 both 
cite using digital data acquisition systems for making resistance 
measurements by the voltmeter-ammeter method and not for no-load 
losses, as was proposed. In an effort to remain aligned with the 
industry testing standard IEEE C57.12.90-2015 and C57.12.91-2020 no-
load loss test, DOE has not adopted the proposal to require automatic 
recording of data using a digital data acquisition system. DOE is 
maintaining the current specification in section 4.4.2(b) of appendix A 
that requires recording data ``as close to simultaneously as 
possible.''
d. Test Frequency
    In the May 2019 TP NOPR, DOE proposed to require testing under the 
DOE test procedure to occur only at 60 Hz in appendix A, sections 
3.1(c) and 4.1, in order to align with the industry testing standard 
and provide clarity on the frequency of the test current. 84 FR 20704, 
20711.
    NEMA commented that there was an error in the proposed language of

[[Page 51236]]

section 3.1(c) of Appendix A, stating that the proposed regulatory text 
should read ``Measure resistance with the transformer energized by a DC 
supply'' rather than with a 60 Hz supply as was proposed in the May 
2019 NOPR. (NEMA, No. 30 at p. 5) DOE concurs with NEMA that the 60 Hz 
supply frequency is not applicable to the resistance measurement 
section of the test procedure, only to the loss measurement sections. 
The proposed addition of section 3.1(c) of appendix A, was an error. 
Resistance measurements are already stated as being a ``direct current 
resistance'' measurement in appendix A, section 3.1(b). Therefore, DOE 
is not adopting section 3.1(c) of appendix A as was proposed in the May 
2019 NOPR.
    The proposed language clarifying the ``Test Frequency'' provision 
in appendix A, section 4.1, is aligned with the industry standard to 
test at the ``rated frequency,'' which by the definition of 
distribution transformer at 10 CFR 431.192 is 60Hz. Therefore, this 
proposed addition remains appropriate. DOE did not receive any comment 
in opposition to its proposal to clarify that appendix A, section 4.1, 
is to be conducted with a 60 Hz frequency current. Therefore, DOE is 
adopting the change as proposed to section 4.1.
e. Summary of Updates Adopted in This Final Rule
    Table III.2 summarizes proposed updates to the relevant IEEE 
testing standards that are adopted in this final rule. As summarized 
previously, DOE received comments from industry trade organizations and 
individual manufacturers indicating that the proposed updates are 
already industry practice and would not change any values or increase 
testing costs for manufacturers. (Howard, No. 32 at p. 1; NEMA, No. 30 
at p. 3; CDA, No. 29 at p. 2; HVOLT, No. 27 at p. 91) As such, DOE has 
determined that the following amendments reflect current industry 
practice and provide additional specificity that will improve the 
repeatability of the test procedure.

       Table III.2--IEEE-Based Updates Adopted in This Final Rule
------------------------------------------------------------------------
                 Topic                   Updates based on IEEE standards
------------------------------------------------------------------------
Consolidating the Terms ``Oil,''         Replace the term ``oil'' and
 ``Transformer Liquid,'' and              ``transformer liquid'' with
 ``Insulating Liquid''.                   ``insulating liquid'' in
                                          Appendix A to reflect that the
                                          term is inclusive of all
                                          insulating liquids, including
                                          those identified in IEEE
                                          C57.12.90-2015.
Stability Requirement for Resistance     Specify, consistent with IEEE
 Measurement.                             C57.12.90-2015, that
                                          resistance measurements are
                                          considered stable if the top
                                          insulating liquid temperature
                                          does not vary more than 2
                                          [deg]C in a one-hour period.
                                          (Appendix A, section
                                          3.2.1.2(b))
Temperature Test System Accuracy.......  Relax the temperature test
                                          system accuracy requirements
                                          to be within 1.5
                                          [deg]C for liquid-immersed
                                          distribution transformers, and
                                          2.0 [deg]C for
                                          MVDT and LVDT distribution
                                          transformers, as specified in
                                          IEEE C57.12.00-2015 and IEEE
                                          C57.12.01-2020, respectively.
                                          (Appendix A, section 2.0)
Limits for Voltmeter-Ammeter Method....  Permit use of the voltmeter-
                                          ammeter method when the rated
                                          current of the winding is less
                                          than or equal to 1 A. Neither
                                          IEEE C57.12.90-2015 nor IEEE
                                          C57.12.91-2020 restrict usage
                                          of this method to certain
                                          current ranges. (Appendix A,
                                          section 3.3.2(a))
Number of Readings Required for          Include the requirement that a
 Resistance Measurement.                  minimum of four readings for
                                          current and voltage must be
                                          used for each resistance
                                          measurement, as specified in
                                          IEEE C57.12.90-2015. (Appendix
                                          A, section 3.3.2(b))
Connection Locations for Resistance      Add resistance measurement
 Measurements.                            specifications for single-
                                          phase windings, wye windings
                                          and delta windings, as
                                          provided in section 5.4.1 and
                                          5.4.2 of IEEE C57.12.90-2015,
                                          and sections 5.6.1 through
                                          5.6.3 of IEEE C57.12.91-2020.
                                          (Appendix A, section 3.4.1(g)-
                                          (i))
Test Frequency.........................  Require that all testing under
                                          the DOE test procedure is to
                                          occur only at 60 Hz. (Appendix
                                          A, section 4.1)
Polarity of Core Magnetization.........  Require that the polarity of
                                          the core magnetization be kept
                                          constant during all resistance
                                          readings. (Appendix A, section
                                          3.4.1(f))
------------------------------------------------------------------------

C. Definitions

    Definitions pertaining to distribution transformers are provided at 
10 CFR 431.192. The following sections discuss new and amended 
definitions established in this final rule.
1. Rectifier Transformers and Drive Transformers
    DOE defines rectifier transformer as a transformer that operates at 
the fundamental frequency of an alternating-current system and that is 
designed to have one or more output windings connected to a 
rectifier.\9\ 10 CFR 431.192.
---------------------------------------------------------------------------

    \9\ A rectifier is an electrical device for converting 
alternating current to direct current.
---------------------------------------------------------------------------

    DOE defines drive (isolation) transformer as a transformer that (1) 
isolates an electric motor from the line; (2) accommodates the added 
loads of drive-created harmonics; and (3) is designed to withstand the 
mechanical stresses resulting from an alternating current adjustable 
frequency motor drive or a direct current motor drive. 10 CFR 431.192. 
The parenthetical inclusion of the term ``isolation'' indicates that 
the defined term includes only isolation transformers and not other 
transformers that may be described as ``drive transformers'' in the 
industry but which do not satisfy all three criteria specified in the 
definition of drive (isolation) transformer.
    Both rectifier transformers and drive transformers are among the 
exclusions to the term ``distribution transformer'' at 10 CFR 431.192 
and 42 U.S.C. 6293(35)(B)(ii). Because both rectifier transformers and 
drive transformers are not classified as distribution transformers, 
they are not subject to the energy conservation standards at 10 CFR 
431.196.

[[Page 51237]]

    Although rectifier transformers and drive transformers are defined 
differently, they typically share features. As discussed in the May 
2019 NOPR, both are isolation transformers (i.e., not 
autotransformers); both are typically exposed to (and must tolerate) 
significant harmonic content created from the drive or power supply; 
and both are likely to include design features enabling them to bear 
mechanical stress resulting from rapid current changes that may arise 
from operation of motors and other industrial equipment. 84 FR 207054, 
20708.
    In response to the September 2017 RFI, Babanna Suresh (``Suresh'') 
commented that it could be argued that most distribution-type 
transformers meet the present definition of the terms ``rectifier 
transformer'' or ``drive transformer'' and suggested that those terms 
be removed from the list of exclusions to the term ``distribution 
transformer.'' (Suresh, Docket No. EERE-2017-BT-TP-0055, No. 9 at p. 1) 
Suresh further suggested that the definition of ``rectifier 
transformer'' be limited to transformers that supply loads that are 
composed of at least 75 percent power electronics. Id.
    In the May 2019 NOPR, DOE stated that the definition of ``rectifier 
transformer'' is not intended to cover a large number of transformers 
intended for general power service; and that linking the definition to 
a percentage of supply load from power electronics would be 
insufficient to designate a distribution transformer because it may not 
be possible for a manufacturer to know in advance what fraction of a 
distribution transformer's load will include power electronics. 84 FR 
207054, 20708. Based on further review of industry testing standards 
and available manufacturer literature, DOE further stated that it was 
unable to identify physical attributes that could be used to reliably 
identify rectifier transformers. Id.
    DOE requested comment on whether the current definitions of 
rectifier transformer and drive transformer are sufficiently specific; 
the level of technical similarity between the two types of 
transformers; and whether any physical or electrical properties could 
be used to reliably identify rectifier transformers.
    DOE received written comments from CDA and HVOLT stating that 
defining rectifier transformers as having multiple output windings 
could be a reasonable addition. (CDA, No. 29 at p.1; HVOLT No. 27 at p. 
89) DOE notes that the current definition already specifies that 
rectifier transformers can have ``one or more'' output windings. 10 CFR 
431.192.
    CDA and HVOLT also stated that small drive transformers could meet 
energy conservations standards, but that larger drive transformers are 
more complicated and would have a more difficult time meeting 
standards. (CDA, No. 29 at p.1-2; HVOLT No. 27 at p. 89) While smaller 
drive transformers may be able to meet energy conservation standards, 
the statutory definition for distribution transformer excludes any 
transformer that is designed to be used in a special purpose 
applications and is unlikely to be used in general purpose 
applications, and specifies drive transformers as such an example. 42 
U.S.C. 6291(35)(b)(ii).
    NEMA commented that the current definition for both rectifier 
transformer and drive transformer are sufficient. (NEMA, No. 30 at 
p.2).
    Having considered these comments from interested parties, DOE 
remains unaware of any industry definition or physical features that 
would better define either rectifier transformers or drive 
transformers.
    Therefore, DOE makes no changes to the definitions of ``rectifier 
transformer'' and ``drive transformer'' in this final rule. Both 
varieties of equipment remain excluded from energy conservation 
standards and are therefore excluded from the scope of the test 
procedure (in accordance with the amendment discussed in section III.A 
of this final rule specifying that the scope of the test procedure is 
limited to the scope of the distribution transformers that are subject 
to energy conservation standards). However, as stated in the April 2006 
Final Rule, DOE narrowly construes the exclusions from the definition 
of ``distribution transformer.'' DOE will also take appropriate steps, 
including enforcement action if necessary, if any manufacturer or other 
party erroneously invokes one of the exclusions as a basis for 
marketing a transformer that is a ``distribution transformer,'' but 
does not meet DOE standards. Moreover, to the extent transformers that 
do fall within the exclusions begin to be marketed for standard 
distribution applications, or find widespread use in such applications, 
DOE will examine whether re-defining the relevant exclusions is 
warranted. See 71 FR 24979.
2. New Definitions
    In the May 2019 NOPR, DOE proposed and sought comment on 
definitions for the terms ``per-unit load,'' ``terminal,'' and 
``auxiliary device.'' 84 FR 20704, 20708-20709. These terms are 
referenced in the DOE test procedure but are not currently defined in 
the regulatory text. The following sections discuss comments received 
regarding each of these terms and the definitions established in this 
final rule.
a. Per-Unit Load
    Distribution transformers are regularly operated at capacities 
other than the capacity listed on a distribution transformer's 
nameplate (i.e., the rated load). In general, distribution transformers 
are loaded substantially below their rated load. DOE's current test 
procedure and energy conservation standards for distribution 
transformers use various terms to refer to operating or testing a 
distribution transformer at a capacity other than the rated load, 
including ``percent load,'' ``percent of nameplate-rated load,'' 
``percent of the rated load,'' or ``per unit load level.'' 10 CFR 
431.192, 10 CFR 431.196, and appendix A. DOE proposed to consolidate 
the usage of these various terms into a single term, ``per-unit load'' 
(``PUL'') in all instances identified. 84 FR 20704, 20709. DOE also 
proposed to define ``per-unit load'' to mean the fraction of rated 
load. Id.
    Howard, CDA, and HVOLT supported the proposed term per-unit load. 
(Howard, No. 32 at p.1; CDA, No. 29 at p.2; HVOLT, No. 27 at p. 89) DOE 
did not receive any comments against its proposed definition for per-
unit load or its proposal to consolidate all references to partial 
loading into a single per-unit load term. In order to improve the 
readability of the test procedure, DOE is adopting the proposed 
definition for per-unit load at 10 CFR 431.192. DOE is also 
consolidating all references to partial load operation in 10 CFR 
431.192, 10 CFR 431.196, and appendix A to the defined ``per-unit 
load'' term.
b. Terminal
    In the May 2019 NOPR, DOE proposed to clarify that load and no-load 
loss measurements should be taken only at the distribution transformer 
terminals, as discussed in section III.F.3. As such, DOE proposed to 
define ``terminal'' to mean ``a conducting element of a distribution 
transformer providing electrical connection to an external conductor 
that is not part of the transformer.'' 84 FR 20704, 20709. This 
definition is based on, but not identical to, the definition for 
``terminal'' in IEEE C57.12.80-2010,\10\ ``IEEE Standard

[[Page 51238]]

Terminology for Power and Distribution Transformers.'' IEEE C57.12.80-
2010 defines terminal as ``(A) A conducting element of an equipment or 
a circuit intended for connection to an external conductor. (B) A 
device attached to a conductor to facilitate connection with another 
conductor.''
---------------------------------------------------------------------------

    \10\ IEEE C57.12.80-2010 is currently listed as ``inactive-
reserved'' which means that this standard is ``. . . removed from 
active status through an administrative process for standards that 
have not undergone a revision process within 10 years.'' (See 
www.standard.iee.org). Given that the standard has not been 
superseded and is not listed as inactive-withdrawn, DOE is 
continuing to consider it the current industry standard on standard 
terminology for power and distribution transformers.
---------------------------------------------------------------------------

    Howard commented in agreement with the proposed definition. 
(Howard, No. 32 at p.1) NEMA, CDA and HVOLT preferred DOE to adopt the 
IEEE C57.12.80-2010 definition of ``terminal'' directly. (NEMA, No. 30 
at p. 2; CDA, No. 29 at p. 2; HVOLT, No. 27 at p. 90).
    DOE has reviewed the IEEE definition and while part ``(A)'' is 
similar to the definition proposed in the May 2019 NOPR, part ``(B)'' 
does not clarify that the terminal needs to be external. While adoption 
of industry-developed language would promote further consistency 
between the DOE test procedure and the industry testing standards, DOE 
is concerned that the IEEE definition could be understood to exclude 
busbar losses in testing of distribution transformers because part (B) 
of the IEEE definition does not specify that a terminal is for 
connection to an external conductor. A manufacturer could interpret 
terminal to be any conducting element within the distribution 
transformer, including a conducting element between the busbar and the 
windings. As a result, DOE is adopting the definition of ``terminal'' 
proposed in the May 2019 NOPR at 10 CFR 431.192 as ``a conducting 
element of a distribution transformer providing electrical connection 
to an external conductor that is not part of the transformer.''
c. Auxiliary Device
    Section 4.5.3.1.2 of appendix A specifies that during testing, 
``measured losses attributable to auxiliary devices (e.g., circuit 
breakers, fuses, switches) installed in the transformer, if any, that 
are not part of the winding and core assembly, may be excluded from 
load losses measured during testing.'' DOE has received inquiries from 
manufacturers regarding whether certain other internal components of 
distribution transformers are required by the DOE test procedure to be 
included in the loss calculation, or whether they are considered an 
auxiliary device. In the May 2019 NOPR, DOE proposed to address the 
prior industry questions and establish a definition of the term 
``auxiliary device'' based on a specific list of all components and/or 
component functions that would be considered auxiliary devices and, 
therefore, be optionally excluded from measurement of load loss during 
testing. 84 FR 20704, 20709.
    The auxiliary device examples listed at section 4.5.3.1.2 of 
appendix A (circuit breakers, fuses, and switches) all provide 
protective function, but do not directly aid the transformer's core 
function of supplying electrical power. Additionally, the term 
``device'' indicates a localized nature, rather than a diffuse system 
or property of the transformer.
    DOE proposed to define ``auxiliary device'' to mean ``a localized 
component of a distribution transformer that is a circuit breaker, 
switch, fuse, or surge/lightning arrester.'' DOE requested comment on 
the proposed definition, if any components needed to be added or 
removed from the listed auxiliary devices, and whether it is 
appropriate to include functional component designations as part of a 
definition. Id.
    CDA and HVOLT stated that the proposed definition was adequate. 
(CDA, No. 29 at p.2; HVOLT, No. 27 at p. 90) Howard commented that the 
four components listed are sufficient and a functional designation is 
not needed. (Howard, No. 32 at p.1) NEMA commented that the current 
definitions are adequate and that it is not necessary to define 
auxiliary device. (NEMA, No. 39 at p.2) NEMA did not specify what, if 
any, aspects of the proposed definition would be inadequate. Moreover, 
prior inquiries from industry indicate that the definition of 
``auxiliary device'' would benefit from further detail. DOE did not 
receive any comment suggesting that the proposed definition is 
inadequate. DOE is adopting the definition of auxiliary device in this 
final rule as proposed.
3. Updated Definitions
a. Low-Voltage Dry-Type Distribution Transformer
    EPCA defines a ``low-voltage dry-type distribution transformer'' as 
``a distribution transformer that--(1) Has an input voltage of 600 
volts or less; (2) is air-cooled; and (3) does not use oil as a 
coolant.'' 42 U.S.C. 6291(38).
    In the May 2019 NOPR, DOE proposed to update the definition for 
``low-voltage dry-type distribution transformer'' by replacing the term 
``oil'' with ``insulating liquid'' within the definition, in 
conjunction with DOE's proposal to consolidate multiple terms to 
``insulating liquid,'' as described in section III.B.2. 84 FR 20704, 
20709. DOE proposed this update to reflect that the term is inclusive 
of all insulating liquids, including those identified in IEEE 
C57.12.90-2015. Id.
    Howard, CDA, and HVOLT generally supported using the broader term 
``insulating liquid'' rather than ``oil.'' (Howard, No. 32 at p. 1; 
CDA, No. 29 at p. 2; HVOLT, No. 27 at p.91) NEMA recommended 
harmonizing the definition with the definition provided in IEEE 
C57.12.80-2010. (NEMA, No. 30 at p. 3) IEEE defines a ``low-voltage 
dry-type distribution transformer'' to mean ``a distribution 
transformer that--(1) Has an input voltage of 600 volts or less; (2) 
Has the core and coil assembly immersed in a gaseous or dry-compound 
insulating medium.''
    Of the three components of EPCA's definition of ``low-voltage dry-
type distribution transformer'', the first component (``Has an input 
voltage of 600 volts or less'') was not proposed for revision by either 
the May 2019 NOPR or by commenters. 42 U.S.C. 6291(38). This first 
component of the definition is left unchanged by this final rule.
    Whereas the first component of the definition addresses the ``low-
voltage'' portion of term ``low-voltage dry-type distribution 
transformer'', the second and third components (``is air-cooled''; 
``does not use oil as a coolant'') combine to describe the manner in 
which LVDTs dissipate heat and collectively address the ``dry-type'' 
portion of the term. The comment from NEMA (suggesting that DOE amend 
the definition to reference the core and coil assembly being ``immersed 
in a gaseous or dry-compound insulating medium'') indicates that 
industry generally considers the descriptors ``air cooled; does not use 
oil as a coolant'' to be synonymous with ``immersed in a gaseous or 
dry-compound insulating medium.'' The revision suggested by NEMA would 
also be consistent with DOE's terminology for addressing ``dry type'' 
in the definition of ``medium-voltage dry-type distribution 
transformer'', which DOE defines as a distribution transformer in which 
the core and coil assembly is immersed in a gaseous or dry-compound 
insulating medium, and which has a rated primary voltage between 601 V 
and 34.5 kV. 10 CFR 431.192.
    After further consideration of the May 2019 NOPR proposal, and 
consideration of comments from interested parties in response to that 
proposal, this final rule revises the definition of ``low-voltage dry-
type distribution transformer'' to mean ``a distribution transformer 
that has an input voltage of 600 volts or less and has the core and 
coil assembly immersed in a gaseous or dry-

[[Page 51239]]

compound insulating medium.'' This revised wording harmonizes with the 
industry definition and implements consistent terminology across both 
varieties of dry-type distribution transformers (i.e., low-voltage and 
medium-voltage).
b. Reference Temperature
    The reference temperature is the temperature at which the 
transformer losses must be determined, and to which such losses must be 
corrected if testing is performed at a different temperature. As 
currently defined at 10 CFR 431.192, ``reference temperature'' means 20 
[deg]C for no-load loss, 55 [deg]C for load loss of liquid-immersed 
distribution transformers at 50 percent load, and 75 [deg]C for load 
loss of both low-voltage and medium-voltage dry-type distribution 
transformers, at 35 percent load and 50 percent load, respectively.
    In the May 2019 NOPR, DOE proposed to update the definition for 
``reference temperature'' by removing references to the numerical 
temperature values required for certification with energy conservation 
standards. 84 FR 20704, 20709. DOE proposed to retain the conceptual 
definition of reference temperature and to include in appendix A the 
numerical temperature values for certification with energy conservation 
standards. The updated definition would allow use of the term reference 
temperature outside the context of conditions required for 
certification with energy conservation standards (i.e., voluntary 
representations at additional temperature values, as described in 
section III.D.2.b). DOE proposed ``reference temperature'' to mean the 
temperature at which the transformer losses are determined, and to 
which such losses must be corrected if testing is performed at a 
different temperature.
    Howard and NEMA both supported the updated definition. (Howard, No. 
32 at p. 1; NEMA, No. 30 at p. 3).
    CDA and HVOLT commented that the reference temperature for ambient 
has been used throughout the industry as 20 [ordm]C and that letting 
that number float to other reference temperatures would be confusing to 
industry. (CDA, No. 29 at p. 2; HVOLT, No. 27 at p. 91).
    The reference temperature in the test procedure does not 
necessarily refer to the ambient temperature, because testing can be 
performed at a different temperature, with the results corrected to 
reflect testing at the defined reference temperature. DOE did not 
propose changes to any of these values for the purpose of certification 
with energy conservation standards.
    The updated definition does not specify particular temperature 
values in order to accommodate the use of the term in a context other 
than only the conditions required for certification and compliance, 
i.e., voluntary representations of efficiency at temperatures or PULs 
different from those specified in appendix A. For example, a 
manufacturer voluntarily representing efficiency at 100 percent PUL 
would correct to a reference temperature that is reflective of the 
distribution transformer temperature rise at 100 percent PUL.
    DOE is adopting the updated definition of ``reference temperature'' 
in 10 CFR 431.192 as proposed.

D. Per-Unit Load Testing Requirements

    The efficiency of distribution transformers varies depending on the 
PUL at which the distribution transformer is operated. DOE's energy 
conservation standards for distribution transformers at 10 CFR 431.196 
prescribe the PUL at which the efficiency of the distribution 
transformer must be determined and certified to DOE (i.e., the 
``standard PUL''). The standard PUL is intended to represent the 
typical PUL experienced by in-service distribution transformers over 
their lifetime. For liquid-immersed distribution transformers and 
medium-voltage dry-type distribution transformers, the equipment 
efficiency is certified at a standard PUL of 50 percent. For low-
voltage dry-type distribution transformers, the efficiency is certified 
at a standard PUL of 35 percent. These values were adopted in the April 
2006 Final Rule from NEMA TP 2-1998. 71 FR 24972.
    As described previously, appendix A does not require testing of the 
distribution transformer at the standard PUL; rather, the standard PUL 
is required only for certification of efficiency. Testing can be 
performed at any PUL, with the results mathematically adjusted to 
reflect the applicable standard PUL. Section 5.1 of appendix A provides 
equations to calculate the efficiency of a distribution transformer at 
any PUL based on the testing of the distribution transformer at a 
single PUL. Current industry practice is to test at 100 percent PUL and 
mathematically determine the efficiency at the applicable standard PUL. 
(NEMA, No. 30 at p. 4).
    The efficiency of distribution transformers over the duration of 
its lifetime and across all installations cannot be fully represented 
by a single PUL. A given transformer may be highly loaded or lightly 
loaded depending on its application or variation in electrical demand 
throughout the day. DOE has previously acknowledged that distribution 
transformers may experience a range of loading levels when installed in 
the field. 78 FR 23336, 23350 (April 18, 2013).
    DOE previously acknowledged that the majority of stakeholders, 
including manufacturers and utilities, support retention of the current 
testing requirements; and DOE determined that its existing test 
procedure provides results that are representative of the performance 
of distribution transformers in normal use. Id. DOE further determined 
that potential improvements in testing precision that might result from 
testing at multiple PULs would be outweighed by the complexity and the 
burden of requiring testing at different loadings depending on each 
individual transformer's characteristics. Id.
    In the May 2019 NOPR, DOE stated that it had considered (1) 
revising the single standard PUL \11\ to a multiple-PUL weighted-
average efficiency metric, (2) revising the single standard PUL to an 
alternative single test PUL metric that better represents in-service 
PUL, or (3) maintaining the current single test PUL specifications. 84 
FR 20704, 20714. DOE tentatively determined that the range of in-
service PUL is diverse, and that the available information describing 
in-service PUL is inconclusive. Id. DOE was unable to show that any 
alternative standard PUL(s) would be more representative than the 
current standard PUL and therefore did not propose an amendment of the 
standard PULs. Id. DOE proposed, however, to allow for voluntary 
representations to be made at PULs other than the standard PUL. Id.
---------------------------------------------------------------------------

    \11\ In the May 2019 NOPR, DOE used the term ``test PUL'' to 
refer to ``standard PUL'' as used in this final rule. The term 
``standard PUL'' better reflects that this is referring to the PUL 
at which the energy efficiency must be determined for the purpose of 
complying with the energy conservation standards at 10 CFR 431.196. 
As described previously in this document, testing can be performed 
at any PUL, with the results corrected to the standard PUL.
---------------------------------------------------------------------------

    The following sections summarize comments received on each of these 
considerations, as well as DOE's responses and conclusions.
1. Multiple-PUL Weighted-Average Efficiency Metric
    In the past, DOE has considered a multiple-PUL efficiency metric in 
contemplating whether a weighted-average efficiency metric composed of 
efficiency at more than one PUL may better reflect how distribution 
transformers operate in service. 84 FR 20704, 20713. In the May 2019 
NOPR, DOE expressed concern that a multi-

[[Page 51240]]

PUL metric could increase burden on manufacturers and create challenges 
in consumer education without being more representative of in-service 
PULs than the current metric. Id.
    The Efficiency Advocates suggested that DOE request transformer 
loading data from IEEE's Transformer Committee to analyze the empirical 
data describing PUL variation. (Efficiency Advocates, No. 34 at p. 2) 
The Efficiency Advocates, asserted that the IEEE data shows a wide 
variation in PUL and that DOE should consider a weighted average PUL 
efficiency metric in the DOE test procedure. (Efficiency Advocates, No. 
34 at p. 2).
    DOE has considered a metric based on a weighted average of a 
transformer's efficiency at multiple different PULs. Different 
weighting schemes are possible. For example, the measured efficiencies 
could be weighted by the fraction of operating hours expected at each 
PUL over the lifecycle of a distribution transformer.
    Generally, distribution transformer losses are presented within the 
industry as consisting of no-load losses, which are approximately 
constant with PUL, and load losses, which scale nearly quadratically 
with PUL. Under that set of mathematical assumptions, any particular 
multi-PUL metric \12\ could alternatively be represented by a single-
PUL metric that would yield the same efficiency value. In other words, 
any multi-PUL metric would be replaceable by a certain single-PUL 
metric. Given this, DOE finds no advantage in adopting a multi-PUL 
metric for distribution transformers. A multi-PUL metric would 
represent a slightly more complex way of arriving at the same result 
that could be derived from a carefully chosen single-PUL metric. As a 
result, DOE is not adopting a multi-PUL metric for distribution 
transformers in this final rule.
---------------------------------------------------------------------------

    \12\ Specified as a set of any number of pairs of PUL values and 
weighting coefficient at that PUL.
---------------------------------------------------------------------------

2. Single-PUL Efficiency Metric
    As stated previously, DOE requires distribution transformers' 
efficiency to be certified at a standard PUL of 50 percent for liquid-
immersed distribution transformers and medium-voltage dry-type 
distribution transformers and 35 percent for low-voltage dry-type 
distribution transformers. 10 CFR 431.196.
    In the May 2019 NOPR, DOE stated that it had considered revising 
the single standard PUL to an alternative single test PUL that better 
represents in-service PUL. 84 FR 20704, 20714. DOE tentatively 
determined that the range of in-service PUL values is diverse, and that 
the available information describing in-service PUL is inconclusive. 
Id. DOE was unable to conclude that any alternative standard PUL(s) 
would be more representative than the current standard PUL and, 
therefore, did not propose to amendment the standard PULs. Id.
    In response to the May 2019 NOPR, DOE received comments arguing 
both for and against revising the single-PUL metric; these are 
discussed in detail in sections III.D.2.a and III.D.2.b. These comments 
comport with the idea that distribution transformers' in-service PULs 
reflect diverse operating conditions. After considering the comments 
brought forward by stakeholders and discussed in sections III.D.2.a and 
III.D.2.b. DOE has concluded that revising the PUL is not justified at 
this time for two reasons.
    First, there is significant long-term uncertainty regarding what 
standard PUL would correspond to a representative average use cycle for 
a distribution transformer given their long lifetimes.\13\ The publicly 
available data effectively amounts to a single year from a few 
distribution transformer customers. Given the uncertainty associated 
with future distribution transformer loading, DOE is unable to conclude 
with certainty that a given alternative single-PUL efficiency metric is 
more representative than the current standard PUL.
---------------------------------------------------------------------------

    \13\ DOE determined in the April 2013 ECS Final Rule as having 
an average lifespan of 32 years, and in many cases they may have an 
in-service lifetime that is significantly longer. 78 FR 23336, 
23377.
---------------------------------------------------------------------------

    Second, given the uncertainty of future loading distributions, 
there may be greater risk in selecting too low a standard PUL than too 
high a standard PUL for two reasons. First, the quadratic nature of 
load loss means that absolute power consumption grows more quickly on 
the high side of the standard PUL than on the low side. Second, 
divergence of the costs associated with different categories of loss 
means that there is greater risk associated with selecting too low a 
standard PUL than too high.
    Accordingly, in this final rule, DOE is maintaining the current 
standard PUL specifications. DOE is centralizing the PUL specifications 
in appendix A, as discussed in section III.F.1.
    DOE considered several factors in determining not to revise the 
current standard PUL requirements in this final rule. In section 
III.D.2.a, DOE reviews publicly available in-service PUL data. In 
sections III.D.2.b and III.D.2.c, DOE considers uncertainty in 
estimates of future load growth, its effects on distribution 
transformers' in-service PULs, and the respective risks associated with 
both under- and overestimating actual future in-service PULs.\14\
---------------------------------------------------------------------------

    \14\ See: Section 2.3 of Chapter 2. Analytical Framework, 
Comments from Interested Parties, and DOE Responses of the Prelim 
Technical Support Document (TSD) at Docket No. EERE-2019-BT-STD-
0018-0022.
---------------------------------------------------------------------------

a. Publicly Available Transformer Load Data
    In response to the May 2019 NOPR, the Efficiency Advocates 
suggested that DOE use IEEE's Advanced Meter Information (``AMI'') data 
to inform the PUL rulemaking. (Efficiency Advocates, No. 34 at p. 1) 
Citing IEEE's Distribution Transformer Subcommittee Task Force's 
(``IEEE-TF'') estimates of average in-service PUL for medium-voltage, 
liquid-filled transformers, the Efficiency Advocates suggest in-service 
PULs are significantly lower than the current standard PULs. 
(Efficiency Advocates, No. 34 at p. 2) The Efficiency Advocates 
recommend, if DOE does not base its analysis on AMI data, that DOE use 
PUL values of 35 percent for liquid-immersed transformers, 25 percent 
for low-voltage dry-type distribution transformers, and 38 percent for 
medium-voltage dry-type distribution transformers. (Efficiency 
Advocates, No. 34, at pp. 2-3).
    Cargill commented that the IEEE-TF data suggests average annual 
loading is less than 30 percent of the ``Peak Annual Load''. (Cargill, 
No. 28 at p. 1) Cargill stated that even in the most conservative case 
of peak load equaling nameplate load, the resulting average PUL would 
be less than 30 percent. (Cargill No. 28 at p. 1) NEMA commented that 
it is not aware of any changes in the field that would justify 
modifying the current PUL levels. (NEMA, No. 30 at p. 4).
    DOE examined the data made available through IEEE-TF.\15\ All of 
the data available through the IEEE-TF is for liquid-immersed 
distribution transformers; DOE did not separately receive updated 
loading data for LVDTs or MVDTs.
---------------------------------------------------------------------------

    \15\ See: grouper.ieee.org/groups/transformers/subcommittees/distr/EnergyEfficiency/F20-DistrTransfLoading-Mulkey.pdf.
---------------------------------------------------------------------------

    DOE has identified several limitations and questions regarding the 
data made available through the IEEE-TF. First and foremost, none of 
the datasets of AMI data referred to by the Efficiency Advocates are 
measured transformer loads, rather they are samples of customer load 
connected to specific transformers. Additionally, each dataset

[[Page 51241]]

presented during the IEEE-TF is a sample of customers' AMI data (i.e., 
not a complete population of distribution transformer load data), and 
each carries questions regarding the sampling methodology, 
representativeness, and completeness. DOE does not know what criteria 
were used to select the sample from each existing population of utility 
customers. Further, each data set was also incomplete in terms of 
missing meter readings, non-sequential metering periods, or missing 
unmetered loads (for example, exterior building lighting, utility owned 
equipment, and street lighting are usually on separate unmetered 
tariffs \16\). These unmetered loads, on separate unmetered tariffs, 
would not be accounted for in the AMI data, and would produce the 
effect of underestimating in-service PUL for a given transformer.
---------------------------------------------------------------------------

    \16\ J. Triplett, S. Rinell and J. Foote, ``Evaluating 
distribution system losses using data from deployed AMI and GIS 
systems,'' 2010 IEEE Rural Electric Power Conference (REPC), 2010, 
pp. C1-8, doi: 10.1109/REPCON.2010.5476204.
---------------------------------------------------------------------------

    DOE examined the largest individual sample of data, from Dominion 
Energy, Inc., which consisted of a year of hourly and sub-hourly 
readings for roughly 60,000 AMI meters connected to distribution 
transformers aggregated into zip codes for parts of Virginia and North 
Carolina.\17\ After removing data from AMI meters that were incomplete, 
or that had the quality issues highlighted in the presentation to the 
IEEE-TF (loads with peak-loads that were several times higher than the 
connected transformers capacity), DOE found that the average root mean 
square (RMS) load, as a function of transformer nameplate capacity, 
over the year in question (2018) was substantially higher than the 10 
percent mode value presented to the IEEE-TF. DOE found that average RMS 
in-service PUL for the transformers subject to the DOE test procedure 
and energy conservation standards was 27.8 percent.\18\
---------------------------------------------------------------------------

    \17\ Zip codes were used to aggregate customer AMI data to 
anonymize the data.
    \18\ See: Chapter 7. Energy Use Analysis of the Prelim TSD at 
Docket No. EERE-2019-BT-STD-0018-0022.
---------------------------------------------------------------------------

    After reviewing the IEEE-TF AMI data, DOE agrees with the 
Efficiency Advocates and Cargill that the current data indicates that 
the average, current, in-service, liquid-immersed distribution 
transformer loading is lower than the standard PUL. However, the data 
also indicates that distribution transformers operate over a diverse 
range of operating conditions. The data shows that a single customer 
does not operate a distribution transformer at a single constant PUL. 
Further, a given distribution transformer model may be used at 
different PULs by different customers. The realities of the typical 
range of operations, and issues of data quality and sample completeness 
raise uncertainties regarding the representativeness of the average PUL 
values presented by the IEEE-TF.
    DOE also notes that while the IEEE-TF AMI data provides valuable 
insight into the in-service PUL of liquid-immersed distribution 
transformers, no equivalent, publicly available data has been presented 
for medium-voltage and low-voltage dry-type distribution transformers.
    Another complicating factor in the representativeness of the 
currently available data is that the IEEE-TF AMI data only covers a 
single year of distribution transformer lifespans. Distribution 
transformers have lifespans of several decades and as such, DOE needs 
to consider not only the diversity of operating conditions that 
distribution transformer currently experience but the entire range of 
operating conditions a distribution transformer would experience in its 
lifespan. Additionally, most of the available data are from similar 
geographies, on the Atlantic coast, which would experience similar 
climatic sensitivities, which is not representative of the Nation as a 
whole. Stakeholders identified several possible factors that could 
significantly impact distribution transformer loading in the short to 
medium term, as discussed in section III.D.2.b.
b. Load Growth Uncertainties
    DOE received several comments from stakeholders in response to the 
May 2019 NOPR on the topic of future load growth on distribution 
transformers. Cargill supported maintaining the current standard PUL, 
asserting that as future transformer loads increase, increased 
transformer efficiency could be realized due to conventional core steel 
having a peak efficiency between 45 and 55 percent PUL. (Cargill, No. 
28 at p. 1) Cargill also suggested that utilities are increasingly 
considering overloading transformers during peak demand with the 
objective of replacing larger mineral-oil-filled transformers with 
smaller, cheaper transformers. Such an approach, Cargill asserts, could 
increase average loading to 50 percent and support retaining the 
current standard PULs. (Cargill, No. 28 at p. 2) The Efficiency 
Advocates commented that increased adoption of photovoltaic generation 
(``PV'') will depress peak demand, as it has done in California. The 
Efficiency Advocates also commented that increasing adoption of 
electric vehicles (``EVs'') is unlikely to contribute to peak demand 
and load growth because it is in utilities' interest to encourage off-
peak charging. (Efficiency Advocates, No. 34 at p. 3) Further, the 
Efficiency Advocates recommended against DOE's continued use of a 1 
percent average annual increase, claiming that based on past experience 
and future projections, load growth of this magnitude is unlikely. 
(Efficiency Advocates, No. 34 at pp. 4) Finally, the Efficiency 
Advocates asserted that increases in demand due to population growth 
will be met with the installation of new transformers, rather than 
increasing loads on existing transformers. (Efficiency Advocates, No. 
34 at p. 2-3).
    HVOLT and CDA commented that standard PUL changes are not needed 
right now, but that EV charging in the future may increase loading. 
(CDA, No. 29 at p. 89; HVOLT, No. 27 at p. 94).
    Load growth has always been, and continues to be, difficult to 
predict. Stakeholders disagreed as to what future distribution 
transformer loading would be expected. While IEEE-TF data suggests that 
the current in-service PUL is lower than the standard PUL, the extent 
to which distribution transformer load will change over time is 
unclear. Distribution transformers were evaluated in the April 2013 ECS 
Final Rule as having an average lifespan of 32 years, and in many cases 
they may have an in-service lifetime that is significantly longer. 78 
FR 23336, 23377. The long lifetime of distribution transformers means 
that many will operate through multiple economic, social, or climate-
driven events that could affect the average in-service PUL on 
individual transformers.
    In response to Cargill, while many conventional core steel 
transformers have a peak efficiency between 45 and 55 percent, this is 
not generally the case across the entire market and may in part be 
driven by the 50 percent standard PUL specified in the DOE test 
procedure. Given an alternative standard PUL, conventional core steel 
transformers could be designed with peak efficiencies at other values. 
Further, while some utilities may be considering overloading 
transformers as standard operating practice and could therefore replace 
larger distribution transformers with smaller distribution 
transformers, thereby increasing the in-service PUL of these 
distribution transformers, DOE does not have any data to substantiate 
Cargill's claim that this practice is actually occurring or is expected 
to occur.
    In response to the Efficiency Advocates, DOE generally agrees that 
PV generation as a resource at the level of the transmission grid can 
both reduce

[[Page 51242]]

the overall generation required to serve a population and have 
potential impacts of reducing peak-demand in areas where there is 
enough solar resource to do so. However, when considered at the level 
of the load(s) being served by individual distribution transformers, PV 
generation (or other demand-side generation) will generally reduce the 
load on the transformer only by the quantity of energy consumed on the 
secondary-service side, (i.e., the customer connected side), of the 
transformer. Unless the PV generation is not grid-tied, any surplus 
energy being transformed from secondary-service voltages to primary-
service voltages and fed back into the grid for distribution would 
contribute to the average load of the transformer. Depending on the 
quantity of surplus energy being fed back into the grid, PV generation 
could have the effect of either decreasing or increasing the average 
PUL on an individual distribution transformer. Further, if surplus 
energy is fed back into the grid during peak times, it could have the 
impact of increasing both peak load and average load. A recent study by 
National Renewable Energy Laboratory (``NREL'') and Los Angeles 
Department of Water and Power (``LADWP''), Los Angeles 100% Renewable 
Energy Study (``LA100''), researching the needs to serve the greater 
city of Los Angeles with 100 percent renewable energy, estimated that 
80 percent of existing distribution feeders would need to be upgraded 
due to occurrences of one or more overloading violations with the 
connected transformers.\19\ Integrating PV or other distributed-
generation in a dispatchable manner is a technically complex task, and 
at the transmission level can reduce overall electricity demands; 
however there is also the potential that loads may rise on some 
distribution circuits (and connected distribution transformers) to meet 
these transmission reductions.
---------------------------------------------------------------------------

    \19\ Palmintier, Bryan, Meghan Mooney, Kelsey Horowitz, et al. 
2021. ``Chapter 7: Distribution System Analysis.'' In the Los 
Angeles 100% Renewable Energy Study, edited by Jaquelin Cochran and 
Paul Denholm. Golden, CO: National Renewable Energy Laboratory. 
NREL/TP-6A20-79444-7. www.nrel.gov/docs/fy21osti/79444-7.pdf.
---------------------------------------------------------------------------

    The Efficiency Advocates' claim that EV impacts on peak electricity 
demand and transformer loads may be small, given the assertion that it 
is in the electric utility's interest to promote off-peak charging, is 
incomplete. The Efficiency Advocates cited an article in support of 
their assertion that ``at a macro scale, EVs appear to pose only a 
modest burden on the electric grid''.\20\ However, this position 
oversimplifies the relationship between connected loads, the 
distribution grid, and transmission grid. The article cited by the 
Energy Advocates cautions that at a micro scale, EVs represent a 
significant addition to traditional household loads; and further states 
that the addition of a level 2 residential EV charging station 
contributes a load similar to an additional house on the grid.\21\
---------------------------------------------------------------------------

    \20\ J. Coignard, P. MacDougall, F. Stadtmueller and E. Vrettos, 
``Will Electric Vehicles Drive Distribution Grid Upgrades?: The Case 
of California,'' in IEEE Electrification Magazine, vol. 7, no. 2, 
pp. 46-56, June 2019, doi: 10.1109/MELE.2019.2908794.
    \21\ Ibid.
---------------------------------------------------------------------------

    While there are likely benefits to promoting off-peak charging, or 
other types of structured charging schemes, EV charging is difficult to 
predict and model because EV adoption is still in the early stages. 
While some utility programs have been successful at shifting EV loads 
from peak to off-peak times using time-of-use rates or specific EV 
charging electricity tariffs, offsetting system peak capacity demands, 
the additional load required to charge an EV during non-peak times will 
still contribute to the overall average transformer PUL. Analysis 
conducted for the LA100 study indicates, under the ``moderate'' 
projection, that electrical demand for transportation will be one of 
the largest contributors to distribution load growth over their 
analysis period (2020 through 2045).\22\ The LA100 study addresses the 
load impacts on utility distribution systems, which would be served by 
liquid-immersed medium-voltage distribution transformers, it does not 
address the potential impacts to commercial and industrial customers 
who deploy dry-type distribution transformers. The impact of EV driven 
load growth on dry-type distribution transformers could also be 
significant, particularly if EVs are charged on circuits without 
upgrades to the serving low- or medium-voltage dry-type distribution 
transformers.
---------------------------------------------------------------------------

    \22\ Hale, Elaine, Anthony Fontanini, Eric Wilson, et al. 2021. 
``Chapter 3: Electricity Demand Projections.'' In the Los Angeles 
100% Renewable Energy Study, edited by Jaquelin Cochran and Paul 
Denholm. Golden, CO: National Renewable Energy Laboratory. NREL/TP-
6A20-79444-3. www.nrel.gov/docs/fy21osti/79444-3.pdf.
---------------------------------------------------------------------------

    In response to the September 2017 RFI, the Efficiency Advocates 
challenged DOE's assertion that the record supports a 50 percent PUL 
for liquid-immersed distribution transformers (on the basis that 
increasing future load growth at the rate of one percent per-year would 
result in in-service PULs that would eventually converge with the test 
standard PUL over time was calculated was incorrectly). In the 
September 2017 RFI DOE asserted that with a one-percent future growth 
rate over time, then-current observed RMS PUL values would 
approximately converge to the standard PUL values. 82 FR 44347, 44349. 
In response to the load growth assertions from the Efficiency 
Advocates, DOE examined the trend in sales of electricity to customers 
made available by the Annual Energy Outlook (AEO) in its Electric Power 
Monthly periodical.\23\ DOE first examined the time period highlighted 
by the Efficiency Advocates and confirms that 2018 was a year in which 
sales were much higher than in the preceding period from 2011 through 
2017. DOE notes that while 2018 had the greatest year-on-year growth 
over this period, there were other years with positive growth, and the 
average year-on-year growth for the period between 2011 through 2018 
was 0.4 percent. DOE also finds that the time period highlighted by the 
Efficiency Advocates is not sufficient for this analysis given that the 
average in-service lifetime for distribution transformers is 32 years. 
As such, DOE takes a longer view of the trend of available data when 
considering the impacts of load growth. When examining the 10-year 
rolling average of year-on-year growth for the period 2010 through 
2020, it can be observed that sales of electricity increased for every 
period, except for the periods ending in 2017 and 2020, with an average 
year-on-year increase of 0.3 percent.\24\
---------------------------------------------------------------------------

    \23\ Energy Information Administration, Electric Power Monthly, 
www.eia.gov/electricity/monthly/.
    \24\ Energy Information Administration, {Electric Power Monthly 
December 1997, DOE/EIA-0226(97/12); Electric Power Monthly December 
2011, DOE/EIA-0226(2011/12); Electric Power Monthly December 2017; 
Electric Power Monthly December 2020{time} , www.eia.gov/electricity/monthly/, See for each of the four listed time periods: 
Table 5.1. Sales of Electricity to Ultimate Customers: Total by End-
Use Sector.
---------------------------------------------------------------------------

    As mentioned, the Efficiency Advocates assert that future growth in 
electricity sales will be driven by population growth, which tends to 
cause grid expansion and the installation of new transformers, rather 
than to increase loads on existing transformers. (Efficiency Advocates, 
No. 34 at p. 2-3) DOE partially agrees with the Efficiency Advocates, 
that load growth from new construction would be met with new 
transformers. DOE must consider that the additional factors that drive 
load growth (e.g., weather events, expanding populations, increased 
electrification), impact all connected distribution transformers, not 
just those installed to provide service to new construction, and 
therefore must consider the effect of load growth's

[[Page 51243]]

impact on a transformer's typical use cycle.
    The Efficiency Advocates requested DOE respond to their comment on 
the September 2017 RFI, where the Efficiency Advocates challenged DOE's 
assertion that, for liquid-immersed distribution transformers, future 
load growth (at the rate of one percent per-year), would result in in-
service PULs that would eventually converge with the standard PUL over 
time, and stated that the in-service PUL was calculated incorrectly. 
(Efficiency Advocates, 0015 at p. 1) In the September 2017 RFI, DOE 
asserted that, on average, the initial (first year) RMS PUL for liquid-
immersed transformers ranged from 34 and 40 percent for single- and 
three-phase equipment, respectively, with a one percent annual increase 
over the life of the transformer to account for connected load growth. 
This resulted in a lifetime average PUL of 49 and 56 percent for 
single- and three-phase liquid-immersed transformers, respectively. And 
that it was consistent with the current test procedure requirements of 
rating liquid-immersed transformers at 50 percent PUL. 86 FR 44349. 
After further analysis of the data, DOE agrees with the Efficiency 
Advocates that the load growth impact on PUL in the September 2017 RFI 
was incorrectly calculated. DOE agrees the load growth rates needed to 
support the assertion that the in-service PUL would converge with the 
standards PUL over the transformers typical lifetime in the September 
2017 RFI would need to be greater than the proposed one percent per-
year. While the conclusions drawn in the September 2017 RFI cannot be 
supported, recent market and policy changes since the publication of 
the RFI indicate that the premise that there are uncertainties and 
concerns associated with future load growth, continue to be valid.
c. Risks Associated With Current and Future Losses
    Given the diversity of conditions under which distribution 
transformers are currently operated and the uncertainty as to how 
future changes in connected loads will affect in-service PULs, DOE must 
consider how a single standard PUL would fare in both circumstances in 
which it overestimates and underestimates the in-service PUL. As 
discussed in section III.D.1, a distribution transformer's efficiency 
is determined as a function of the total losses at the standard PUL. A 
distribution transformer's total losses at the standard PUL are the sum 
of its no-load losses and load losses at the standard PUL. No-load 
losses are approximately constant with the PUL and load losses increase 
quadratically with PUL.
    Every distribution transformer has a PUL for which efficiency 
peaks, where no-load and load losses happen to be equal. While there is 
no prescribed PUL at which this must occur, often, as a result of 
optimizations in the manufacturing process, transformers are most 
efficient at, or near, the DOE prescribed standard PUL. Distribution 
transformers that have a peak efficiency at PUL values greater than the 
average in-service PUL overemphasize load losses and distribution 
transformers that have a peak efficiency less than the average in-
service PUL overemphasize no-load losses relative to transformer 
designs with equivalent total losses that peak at the in-service PUL. 
The asymmetry in rate of loss change--the losses rise faster at PULs 
greater than the standard PUL than they fall at PULs less than the 
standard PUL--contributes to the conclusion that the risk of selecting 
a suboptimal standard PUL is greater on the low side than on the high 
side. Efficiency falls in proportion to the degree to which in-service 
PUL diverges from standard PUL. Because a lower in-service PUL 
corresponds (on a single-unit basis) to a lower absolute quantity of 
energy, however, a given loss of efficiency equates to a greater 
absolute quantity of energy when the in-service PUL exceeds standard 
PUL.\25\
---------------------------------------------------------------------------

    \25\ See: Section 2.3 of Chapter 2. Analytical Framework, 
Comments from Interested Parties, and DOE Responses of the Prelim 
TSD at Docket No. EERE-2019-BT-STD-0018-0022.
---------------------------------------------------------------------------

    As stated in section III.D.2.a, the Efficiency Advocates recommend 
DOE select a lower standard PUL to better align with the AMI data. 
(Efficiency Advocates, No. 34, at pp. 2-3) DOE notes that the maximum 
technologically feasible design options analyzed in the April 2013 
Final Rule consist of distribution transformers that have a peak 
efficiency well below the standard PUL (often times below 20 percent 
PUL). 78 FR 23337. This indicates that distribution transformers can be 
built that perform well at both the in-service PULs cited by the 
Efficiency Advocates and meet efficiency standards at the current 
standard PUL. Energy savings achieved through the energy conservation 
standard rulemaking at the current PUL have less of this asymmetric 
risk because they do not discount load losses to the same degree as a 
lower PUL.
    In addition to considering the energy savings potential of the 
standard PUL overestimating and underestimating in-service PUL, DOE 
also considered the financial value of losses to consumers associated 
with overestimating and underestimating in-service PULs.
i. Peak Coincidence Risks
    The Efficiency Advocates suggested that it in the best interest of 
utilities to pursue programs to mitigate risks related to peak demands. 
(Efficiency Advocates, No. 34 at p. 3) Demand response programs can 
help flatten peaks at the grid, distribution, and individual consumer 
levels. A simplified example is a demand response program which 
promotes peak-load shifting, wherein utility ratepayers defer or forego 
electrical consumption during times when the system is peaking. This 
may have a bottom-up effect of reducing peak power through individual 
distribution transformers by reducing peak generation. Owners of 
distribution transformers typically face different costs depending on 
overall demand, which influences the mix of generation and storage they 
may deploy to meet the demand. Large electrical consumers (who with 
electrical utilities generally form the total set of distribution 
transformer owners), too, face demand-based cost of electrical power. 
In general, marginal cost of electricity is greater during times of 
high demand. This carries implications for valuing the losses of 
distribution transformers. Specifically, load losses will tend to be 
costlier for the owner of the distribution transformers as 
proportionally more of them occur during periods of high demand and 
correspondingly higher energy cost.
    By their nature, distribution transformers tend to be ``peak-
coincident'', i.e., the peak load on the distribution transformers 
tends to coincide with peak load on the larger electrical network. That 
distribution transformer loading peaks to when electrical power costs 
peak can result in certain distribution transformer customers bearing 
high operating cost for a small number of peak operating hours. 
Distribution transformers designed without account of this electrical 
cost dynamic, optimized for lower in-service PULs, will operate at 
comparatively low efficiency when the cost of operation is greatest. 
DOE recognizes that demand response programs can reduce the peak-load 
impacts. However, because distribution transformers reflect the load 
patterns of their connected loads, the risks of the high rate of load 
losses associated with peak coincidence cannot be fully controlled by 
utilities and are dependent on consumer patterns. Accordingly, DOE 
needs to maintain a

[[Page 51244]]

PUL which adequately addresses both high and low in-service loads.
ii. Serving Future No-Load and Load Losses
    In evaluating the financial risk to consumers of the standard PUL 
over- and underestimating in-service PULs, and given the long lifespans 
of distribution transformers, DOE needs to consider how future no-load 
and load losses will be served.
    The way in which future electricity generation needs will be met 
has historically been considered in DOE's ECS analyses. However, to the 
extent that the choice of metric affects the cost effectiveness and 
energy consumption (both in the aggregate quantity and the timing of 
that energy consumption) of consumers, some background on the power 
grid (the operating site of distribution transformers) is necessary to 
understand the broader impacts of any metric change. Insofar as 
purchasers of distribution transformers select on the basis of first 
cost, manufacturers may attempt to minimize first cost subject to 
compliance with energy conservation standards. The specific 
distribution transformer design that minimizes first cost may vary 
based on the metric it is being evaluated against. Thus, selection of 
standard PUL may indirectly influence purchase prices and energy 
consumption of distribution transformers.
    In the April 2013 ECS Final Rule, DOE assumed that future power 
needs for no-load losses would be met by the mix of different baseline 
generation types in the year of compliance, 2016. 78 FR 23337. At that 
time, DOE based its analysis on the data available from AEO 2012, which 
indicated a mix of generation types which was predominantly served by 
coal at 26 percent, natural gas combined cycle at 19 percent, 
renewables and natural gas combustion turbines both at 15 percent, with 
the remainder generation being met by other generation types.\26\ DOE 
projected that future no-load losses generation would be met by new 
capacity from coal, as it serves predominantly base load, and natural 
gas and renewables serve a mix of base-, mid-merit and peaking 
loads.\27\ DOE assumed that load losses would be met with simple 
combustion turbines.\28\ This resulted in a cost, in terms of dollars 
per watt, ($/W) for no-load losses that was higher than the cost of 
load losses. A contributing factor to this difference is the relatively 
high overnight capital cost of large coal plants, in terms of dollars 
per megawatt unit capacity, ($/MW) when compared to other generating 
types for determining the capacity cost component of the cost of 
electricity. However, the current AEO 2021 projects a very different 
mix of generating fuel types, now and into the future, with retiring 
coal and, to a lesser degree, nuclear generation being displaced by 
natural gas, in the near-term, and then renewables in future years. 
These trends are shown in Table III.3. This shift in generating fuels 
suggests that the future cost associated with no-load losses and load 
losses will be closer in price than previously estimated as similar 
generating units are used to meet both no-load and load losses.
---------------------------------------------------------------------------

    \26\ Energy Information Administration, Annual Energy Outlook, 
2012, Table 54. Electric Power Projections by Electricity Market 
Module Region.
    \27\ See Chapter 7 of the 2013 final rule TSD, available at 
https://www.regulations.gov/document/EERE-2010-BT-STD-0048-0760.
    \28\ Ibid.

                                      Table III.3--Projected Fraction of Generation by Fuel Types for Certain Years
                                                              [Percent of total generation]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Year                               Coal (%)         Natural gas (%)       Nuclear (%)      Renewable sources   Other sources (%)
-----------------------------------------------------------------------------------------------------------------         (%)                 \*\
                                                        2012      2021                                           ---------------------------------------
                         AEO                            \**\    [dagger]    2012      2021      2012      2021      2012      2021      2012      2021
--------------------------------------------------------------------------------------------------------------------------------------------------------
2010................................................        46  ........        23  ........        20  ........        10  ........         1  ........
2015................................................        39  ........        26  ........        21  ........        13  ........         1  ........
2020................................................        40        20        24        40        22        20        13        20         1         0
2025................................................        41        17        24        35        21        18        14        29         1         0
2030................................................        40        16        25        34        21        15        13        34         1         0
2035................................................        40        15        26        33        19        14        14        37         1         0
2040................................................  ........        14  ........        34  ........        13  ........        38  ........         0
2045................................................  ........        12  ........        35  ........        13  ........        39  ........         0
2050................................................  ........        12  ........        35  ........        12  ........        41  ........         0
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Includes the following generation fuel-type categories: Distributed Generation, Generation for Own Use, Petroleum, Pumped Storage/Other.
** Source: U.S. Energy Information Administration, Annual Energy Outlook 2012, Electricity Electric Power Sector Generation (Case Reference case Region
  United States).
[dagger] Source: U.S. Energy Information Administration, Annual Energy Outlook 2021, Electricity Electric Power Sector Generation (Case Reference case
  Region United States).

    As stated previously, in this final rule, DOE is maintaining the 
current standard PUL specifications. DOE is centralizing the PUL 
specifications in appendix A, as discussed in section III.F.1.
    Further, the test procedure and accompanying energy conservation 
standards do not preclude manufacturers from optimizing distribution 
transformer performance at a PUL other than the standard PUL so long as 
the unit complies with the applicable standard when tested at the 
standard PUL. While reducing the standard PUL could in certain cases 
have a positive impact on energy savings, especially for distribution 
transformers fabricated with low-loss core materials such as amorphous 
steel, the same energy savings outcome can often be achieved through 
amending the energy conservation standard for distribution 
transformers. In other words, the savings associated with a potential 
reduction of standard PUL is often a byproduct of greater consumer 
selection of amorphous-based transformers, which by chance tend to both 
be relatively better at smaller PUL values and also be more efficient 
in absolute terms. Many of the distribution transformer designs in the 
accompanying energy conservation standards preliminary engineering 
analysis with efficiencies above the current standard are optimized to 
operate at a PUL below 25 percent due to the use of amorphous steel 
cores, while certifying at the current standard PUL. It is in the 
accompanying energy conservation standards where details and data 
related to the efficiency standards of distribution transformers can be 
fully evaluated under the EPCA requirements that any new or amended 
energy conservation standard be designed to achieve the maximum 
improvement in energy or water

[[Page 51245]]

efficiency that is technologically feasible and economically justified. 
(42 U.S.C. 6316(a); 42 U.S.C. 6295(o)(2)(A)) DOE is also permitting 
voluntary representations of efficiency at additional PULs so that 
manufacturers can communicate to customers the efficiency of their 
distribution transformers at various service PULs, as discussed in 
section III.D.3. Additionally, voluntarily representations at 
additional PULs may be relied upon by voluntarily programs such as 
ENERGY STAR[supreg], which publishes a buying guide \29\ to assist 
distribution transformer purchasers that may save energy and cost in 
the context of the purchasers' specific PUL distribution.
---------------------------------------------------------------------------

    \29\ United States Environmental Protection Agency. ENERGY 
STAR[supreg] Guide to Buying More Energy Efficient Distribution 
Transformers. October 2017. Accessed July 7, 2021. https://www.energystar.gov/sites/default/files/asset/document/Transformers%20Buyer%27s%20GuideFinal10-16-17.pdf.
---------------------------------------------------------------------------

    Finally, DOE notes that the observable data and trends indicate 
that there are ongoing changes in policies, consumer demand, and data 
availability which are beginning to have an impact on the distribution 
transformer operations. These changes present uncertainties with regard 
to distribution transformer loading, and DOE will continue to evaluate 
changes in the market and in operation that may require consideration 
in future test procedure evaluations.
3. Voluntary Representations of Efficiency at Additional PULs
    In the May 2019 NOPR, DOE proposed amendments to the test procedure 
to permit manufacturers to make voluntary representations of additional 
performance information of distribution transformers when operated 
under conditions other than those required for compliance with the 
energy conservation standards for distribution transformers at 10 CFR 
431.196. 84 FR 20704, 20714. DOE proposed the provisions regarding 
voluntary representations to help consumers make better purchasing 
decisions based on their specific installation conditions. 
Specifically, DOE proposed in a new section 7 of appendix A to specify 
that manufacturers are permitted to represent efficiency, no-load loss, 
or load loss at additional PULs and/or reference temperatures, as long 
as the equipment is also represented in accordance with DOE's test 
procedure at the mandatory (standard) PUL and reference temperature. 
When making voluntary representations, best practice would be for the 
manufacturers also to provide the PUL and reference temperature 
corresponding to those voluntary representations.
    NEMA stated that the current test procedure is already applicable 
to alternative PULs. (NEMA, No. 30 at p. 4) Howard, CDA, and HVOLT 
commented that voluntary representations would be useful in examining 
efficiencies at alternative PULs. (Howard, No. 32 at p. 1; CDA, No. 29 
at p. 3; CDA, No. 29 at p. 4; HVOLT, No. 27 at p. 92-94)
    As discussed, while the test procedure accommodates testing at any 
PUL, and correcting the results to reflect any other specified PUL, 
DOE's energy conservation standards specify standard PULs that must be 
used to represent the energy efficiency of distribution transformers. 
10 CFR 431.196. EPCA prohibits manufacturers from making 
representations respecting the energy consumption of covered equipment 
or cost of energy consumed by such equipment unless that equipment has 
been tested in accordance with the applicable DOE test procedure and 
such representations fairly disclose the results of that testing. (42 
U.S.C. 6314(d)) Accordingly, there is benefit in manufacturers being 
explicitly permitted to make representations respecting energy 
consumption at alternative PULs and reference temperatures that may 
better suit an individual consumer's demands.
    For the reason expressed in the May 2019 NOPR and above, DOE is 
establishing new section 7 of appendix A, which explicitly provides 
that any PUL and temperature values other than those required for 
determining compliance can be used for voluntary representations when 
testing is conducted in accordance with the applicable DOE test 
procedure. Table III.4 summarizes the applicable PUL and temperature 
values.

                                                    Table III.4--Summary of Voluntary Representation
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Mandatory certified values *                                 Voluntary representations
                                 -----------------------------------------------------------------------------------------------------------------------
                                                                          Reference
                                                                         temperature                                               Reference temperature
                                         Metric         PUL (percent)  for loead loss         Metric            PUL (percent)             ([deg]C)
                                                                          ([deg]C)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Liquid Immersed.................  Efficiency.........              50              55  Efficiency, load     Any..................  Any.
                                                                                        loss, no-load loss.
MVDT............................  ...................              50              75
LVDT............................  ...................              35              75
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Efficiency must be determined at a reference temperature of 20 [deg]C for no-load loss for all distribution transformers.

E. Multiple Voltage Capability

    Some distribution transformers have primary windings 
(``primaries'') and secondary windings (``secondaries'') that may each 
be reconfigured, for example either in series or in parallel, to 
accommodate multiple voltages. Some configurations may be more 
efficient than others.
    Section 4.5.1(b) of appendix A requires that for a transformer that 
has a configuration of windings that allows for more than one nominal 
rated voltage, the load losses must be determined either in the winding 
configuration in which the highest losses occur, or in each winding 
configuration in which the transformer can operate. Similarly, section 
5.0 of appendix A states that for a transformer that has a 
configuration of windings that allows for more than one nominal rated 
voltage, its efficiency must be determined either at the voltage at 
which the highest losses occur, or at each voltage at which the 
transformer is rated to operate. Under either testing and rating option 
(i.e., testing only the highest loss configuration, or testing all 
configurations), the winding configuration that produces the highest 
losses is tested and consequently must comply with the applicable 
energy conservation standard.

[[Page 51246]]

    The relevant industry test standards, IEEE C57.12.00-2015 and IEEE 
C57.12.01-2020, direct distribution transformers to be shipped with the 
windings in series. Therefore, a manufacturer physically testing for 
DOE compliance may need to disassemble the unit, reconfigure the 
windings to test the configuration that produces the highest losses, 
test the unit, then reassemble the unit in its original configuration 
for shipping, which would add time and expense.
    In the May 2019 NOPR, DOE did not propose amending the requirement 
related to transformers being tested in the configuration that produces 
the highest losses. 84 FR 20704, 20718. DOE noted that it provides for 
certification using an alternative efficiency determination method 
(AEDM), which is a mathematical model based on the transformer design 
(10 CFR 429.47), and that the availability of an AEDM mitigates the 
potential cost associated with having to physically test a unit in a 
configuration other than in its ``as-shipped'' configuration. Id.
    Howard, NEMA, CDA and HVOLT suggested that transformers be tested 
in the ``as-shipped'' configuration, which is typically with the 
windings in series. (Howard, No 32 at p. 1; CDA, No. 29 at p. 3; HVOLT, 
No. 27 at p. 92; NEMA, No. 30 at p. 6) NEMA commented that the 
requirement to test in the highest losses configuration is confusing to 
customers and adds undue burden on manufacturers, whereas industry 
testing standards have changed to test and ship in highest voltage 
configurations. (NEMA, No. 30 at p. 6) NEMA claims the burden 
associated with requiring testing of the configuration with the highest 
loss is especially unnecessary given that the overwhelming majority of 
transformers are used in the highest voltage configuration, with less 
than 5% of transformers in applications other than the ``as-shipped'' 
configuration. (NEMA, No. 30 at p. 6) NEMA asserted that while it can 
be hard to generalize the losses associated with less efficient winding 
configurations, given the variability in application, the losses are 
typically less than 1% of load losses, and that it has never seen the 
difference between configurations exceed 2% of load losses. (NEMA, No. 
30 at p. 4; NEMA, No. 30 at p. 6) NEMA further asserted that given the 
minimal efficiency gains in testing in the highest-loss and the 
relatively small percentage of transformers operated in a configuration 
other than ``as-shipped'', the burden on manufacturers is not 
justified. (NEMA, No. 30 at p. 6)
    As stated in the May 2019 NOPR, DOE recognizes that testing in the 
as-shipped condition may be less burdensome for certain manufacturers, 
but DOE also stated that it does not have data to support NEMA's claim 
that the ``as-shipped'' configuration would lead to a maximum of 2 
percent increase in load losses. 84 FR 20704, 20718. NEMA cited certain 
example distribution transformers where the load loss increase was 2 
percent or less, however, the data is only for a few select 
distribution transformers and not representative of the industry as a 
whole. (NEMA, No. 30 at p. 7) In interviews, several manufacturers 
suggested that in certain extreme cases the difference in efficiency 
could be much higher than the 2 percent figure cited by NEMA.
    Further, even if DOE did have data affirming the 2 percent figure 
NEMA cited, it would be expected that such a change to the test 
procedure would require a corresponding change to the energy 
conservation standards to account for the change in measured load loss 
values. A change to the energy conservation standards would necessitate 
certain manufacturers of transformers with multiple windings to re-test 
and re-certify their performance to DOE.
    As explained in the May 2019 NOPR, as an alternative to physical 
testing, DOE provides for certification using an AEDM, which is a 
mathematical model based on the transformer design. 10 CFR 429.47. The 
shipped configuration has no bearing on the AEDM calculation, and an 
AEDM can determine the highest-loss configuration instantly. DOE notes 
that most transformers are currently certified using the AEDM and the 
current burden is therefore less than the commenters asserted for the 
majority of manufacturers. In interviews, manufacturers suggested that 
this burden existed only when verifying an AEDM. Further, many 
distribution transformers are reconfigured using a switch, which 
minimizes effort required to change winding configurations. NEMA 
confirmed that there is no burden associated with rewiring when 
utilizing an AEDM and rather that the benefit to changing to ``as-
shipped'' testing is that for higher-volume, single-phase pole mount 
units manufacturers could continually gauge the ``as-shipped'' 
performance against the AEDM. (NEMA, Docket No. EERE-2017-BT-TP-0055-
0036 at p. 3) While there may be benefits in continually gauging the 
``as-shipped'' performance against the AEDM, DOE remains concerned 
about the magnitude of the increase in load losses for certain 
distribution transformers.
    As a result, DOE is not amending in this final rule the current 
requirements of section 4.5.1(b) of appendix A (for a transformer that 
has a configuration of windings that allows for more than one nominal 
rated voltage, the load losses must be determined either in the winding 
configuration in which the highest losses occur, or in each winding 
configuration in which the transformer can operate) and section 5.0 of 
appendix A (for a transformer that has a configuration of windings that 
allows for more than one nominal rated voltage, its efficiency must be 
determined either at the voltage at which the highest losses occur, or 
at each voltage at which the transformer is rated to operate).

F. Other Test Procedure Topics

    In addition to the updates to the DOE test procedure discussed in 
the preceding sections, DOE also considered whether the existing test 
procedure would benefit from any further revisions and/or reorganizing. 
Additional issues are discussed in the following sections.
1. Per-Unit Load Specification
    In the May 2019 NOPR, DOE proposed to centralize the PUL 
specifications, both for the certification to energy conservation 
standards and for use with a voluntary representation. 84 FR 20704, 
20718-20719. Currently, the PULs required for certification to energy 
conservation standards are specified for each class of distribution 
transformer at 10 CFR 431.196 and referenced indirectly in multiple 
locations, including 10 CFR 431.192 (within the definition of reference 
temperature), section 3.5(a) of appendix A, and section 5.1 of appendix 
A. DOE proposed to consolidate the PUL specification into one 
location--a newly proposed section 2.1 of appendix A. Additionally, DOE 
proposed to provide in the proposed section 2.1 of appendix A that the 
PUL specification can be any value for purposes of voluntary 
representations. Id. DOE did not receive any comments on these proposed 
changes and is adopting them in this final rule.
    The consolidation enhances readability of the test procedure and 
more clearly communicates the PUL requirements with respect to 
certification to energy conservation standards and voluntary 
representations. The updates do not change the standard PUL 
requirements with respect to certification to energy conservation 
standards. Instead, the updates improve clarity with respect to 
selection of PUL for voluntary

[[Page 51247]]

representations versus certification to energy conservation standards.
    DOE also proposed editorial changes to section 5.1 of appendix A to 
support the consolidated approach to PUL specification. 84 FR 20704, 
20719. Section 5.1 of appendix A provides equations used to calculate 
load-losses at any PUL. Section 5.1 of appendix A used language that 
limited its applicability to certification to energy conservation 
standards only. For example, it referenced the ``specified energy 
efficiency load level'' (i.e., the PUL required for certification to 
energy conservation standards) specifically. DOE proposed to generalize 
the language in this section to reference the PUL selected in the 
proposed section 2.1. Id.
    DOE did not receive any comments regarding these proposed editorial 
changes and is adopting them in this final rule.
2. Reference Temperature Specification
    Similar to PUL, DOE proposed to consolidate the reference 
temperature specifications for certification to energy conservation 
standards and for the proposed voluntary representations. 84 FR 20704, 
20719. The reference temperature specifications for certification to 
energy conservation standards are defined at 10 CFR 431.192 (as the 
definition of ``reference temperature''), and are referenced in section 
3.5(a) of appendix A and section 4.4.3.3 of appendix A. DOE proposed to 
consolidate the reference temperature specifications into one 
location--a newly proposed section 2.2 of appendix A. 84 FR 20704, 
20719. Additionally, DOE proposed to describe in the proposed section 
2.2 of appendix A that the reference temperature specification can be 
any value for purposes of voluntary representations. Id. DOE did not 
receive any comments on the proposed changes and is adopting them in 
this final rule.
    Similar to PUL, this consolidation will enhance readability of the 
test procedure and more clearly communicate DOE's reference temperature 
requirements with respect to certification to energy conservation 
standards or voluntary representations. The updates do not change 
existing reference temperature requirements with respect to 
certification to energy conservation standards. Instead, the updates 
improve clarity with respect to selection of reference temperature for 
voluntary representations versus certification to energy conservation 
standards.
    DOE also proposed editorial changes to sections 3.5 and 4.4.3.3 of 
appendix A to support the consolidated approach to reference 
temperature specification. Section 3.5 of appendix A provided reference 
temperatures for certification to energy conservation standards. DOE 
has consolidated reference temperature specifications into one location 
(section 2.2); therefore, DOE has removed the same specification in 
section 3.5 so that the section is applicable to determine voluntary 
representations.
    Section 4.4.3.3 of appendix A provides the specifications and 
equations used for correcting no-load loss to the reference 
temperature. Specifically, the section provides an option for no 
correction if the no-load measurements were made between 10 [deg]C and 
30 [deg]C (representing a 10 [deg]C tolerance around the 20 
[deg]C reference temperature). This tolerance is applicable only for 
certification to energy conservation standards. For simplicity, DOE 
proposed no such tolerance for voluntary representations at additional 
reference temperatures, so that all measured values would be adjusted 
using the reference temperature correction formula. 84 FR 20704, 20719. 
Finally, DOE proposed to remove any reference to a reference 
temperature of 20 [deg]C so that the section would be applicable to 
determine voluntary representations. Id.
    DOE did not receive any comments on these proposed changes and is 
adopting them in this final rule.
3. Measurement Location
    DOE proposed to specify that load and no-load loss measurements are 
required to be taken only at the transformer terminals. 84 FR 20704, 
20719. In the May 2019 NOPR, DOE proposed a definition for 
``terminal,'' as described in section III.C.2.b of this final rule. DOE 
notes that section 5.4 of IEEE.C57.12.90-2015 and section 5.6 of IEEE 
C57.12.91-2020 specify terminal-based load-loss measurements. In 
addition, section 8.2.4 of IEEE.C57.12.90-2015 and section 8.2.5 of 
IEEE C57.12.91-2020 provide the same for no-load loss measurement. 
These documents reflect current industry practices and manufacturers 
are already measuring losses at the transformer terminals. Therefore, 
DOE proposed to specify in section 4.3(c) of appendix A that both load 
loss and no-load loss measurements must be made from terminal to 
terminal. 84 FR 20704, 20719.
    DOE received no comments in response to this proposal and is 
adopting it in this final rule.
4. Specification for Stabilization of Current and Voltage
    Section 3.3.2 and 3.3.1 of appendix A describe a voltmeter-ammeter 
method and resistance bridge methods, respectively, for measuring 
resistance. Both methods require measurements to be stable before 
determining the resistance of the transformer winding being measured. 
Specifically, the voltmeter-ammeter method in section 3.3.2(b) of 
appendix A requires that current and voltage readings be stable before 
taking simultaneous readings of current and voltage to determine 
winding resistance. For the resistance bridge methods, section 3.3.1 of 
appendix A requires the bridge to be balanced (i.e., no voltage across 
it or current through it) before determining winding resistance. Both 
methods allow for a resistor to reduce the time constant of the 
circuit, but do not explicitly specify how to determine when 
measurements are stable. DOE notes that IEEE C57.12.90-2015, IEEE 
C57.12.91-2020, IEEE C57.12.00-2015, and IEEE C57.12.01-2020 do not 
specify how to determine that stabilization is reached. Section 3.4.2 
of appendix A provides related instruction for improving measurement 
accuracy of resistance by reducing the transformer's time constant. 
However, section 3.4.2 also does not explicitly provide for the period 
of time (such as a certain multiple of the time constant) necessary to 
achieve stability. In the May 2019 NOPR, DOE requested comment on how 
industry currently determines that measurements have stabilized before 
determining winding resistance using both voltmeter-ammeter method and 
resistance bridge methods. 84 FR 20704, 20719.
    NEMA commented that testing is typically done with a computer/
electronic automatic test system where the feature is provided. NEMA 
stated that its members have not used a resistance bridge method in 20 
years. (NEMA, No. 30 at p. 4) HVOLT and CDA commented that both the 
resistance bridge and voltmeter-ammeter methods should be accurate as 
long as four-time constants have passed. (HVOLT, No. 27 at p. 93; CDA, 
No. 29 at p. 3)
    Commenters have not suggested that there is an issue with the 
accuracy of measurements associated with achieving sufficient stability 
and did not suggest that DOE needed to explicitly provide for the 
period of time necessary to achieve stability. Therefore, DOE has not 
adopted any amendments related to the period of time to achieve 
stability.

[[Page 51248]]

5. Ambient Temperature Tolerances
    In response to the September 2017 RFI, NEMA recommended that DOE 
increase the ambient temperature tolerances for testing dry-type 
transformers, stating that testing may otherwise be burdensome in 
laboratories that are not climate controlled, and that a mathematical 
correction factor could be developed as an alternative to the 
temperature limits. (NEMA, Docket No. EERE-2017-BT-0055-0014 at p. 2)
    In the May 2019 NOPR, DOE explained that while widening the 
tolerances of temperatures (or other measured parameters) may reduce 
testing cost, it may impact the reproducibility and repeatability of 
the test result. 84 FR 20704, 20719-20720. Further, NEMA acknowledged 
that manufacturers are not having difficulty meeting the temperature 
requirement. (NEMA, Docket No. EERE-2017-BT-0055-0014 at p. 8)
    DOE does not have data regarding typical ranges of laboratory 
ambient temperature and, as a result, cannot be certain that reduction 
in temperature tolerance would not impact reproducibility, 
repeatability, and accuracy and cause future test results to become 
incomparable to past data. For these reasons, DOE did not propose 
amendments to the laboratory ambient temperature and transformer 
internal temperature requirements in the May 2019 NOPR. 84 FR 20704, 
20720.
    Comments received on this issue supported maintaining the current 
ambient temperature tolerances. (Howard, No. 31 at p. 1; NEMA, No. 30 
at p. 4; CDA, No. 29 at p. 3; HVOLT, No. 27 at p. 93) For the reasons 
discussed in the May 2019 NOPR and in the preceding paragraph, DOE is 
maintaining the ambient temperature requirements in appendix A.
6. Harmonic Current
    Harmonic current refers to electrical power at alternating current 
frequencies greater than the fundamental frequency. Distribution 
transformers in service are commonly subject to (and must tolerate) 
harmonic current of a degree that varies by application. Sections 
4.4.1(a) and 4.4.3.2(a) of appendix A direct use of a sinusoidal 
waveform for evaluating efficiency in distribution transformers.
    DOE recognizes that transformers in service are subject to a 
variety of harmonic conditions, and that the test procedure must 
provide a common basis for comparison. Currently, the test procedure 
states that transformers designed for harmonic currents must be tested 
with a sinusoidal waveform (i.e., free of harmonic current), but does 
not do so for all other varieties of transformers. However, the intent 
of the test procedure is for all transformers to be tested with a 
sinusoidal waveform, as is implicit in section 4.4.1(a) of appendix A. 
To clarify this test setup requirement, DOE proposed to modify section 
4.1 of appendix A to read ``. . . Test all distribution transformers 
using a sinusoidal waveform (k=1).'' 84 FR 20704, 20720 This is 
consistent with industry practice and manufacturers are already testing 
all distribution transformers using a sinusoidal waveform. Id.
    DOE received several comments in support of this clarification and 
none in opposition. (Howard, No. 32 at p. 2; NEMA, No. 30 at p. 4; CDA, 
No. 29 at p. 3; HVOLT, No. 27 at p. 93) For the reasons discussed in 
the May 2019 NOPR and in the preceding paragraph, DOE is adopting the 
clarification regarding use of a sinusoidal waveform as proposed.
7. Other Editorial Revisions
    In the May 2019 NOPR, DOE proposed the following editorial updates 
to improve the readability of the test procedure and provide additional 
detail: (i) Revising ``shall'' (and a single instance of ``should'' in 
the temperature condition requirements at section 3.2.2(b)(3)) to 
``must'' throughout appendix A, (ii) clarifying the instructional 
language for recording the winding temperature for dry-type 
transformers (section 3.2.2 of appendix A), (iii) separating certain 
sentences into enumerated clauses (section 3.2.2(a) of appendix A),\30\ 
(iv) identifying the corresponding resistance measurement method 
sections (section 3.3 of appendix A), (v) replacing a reference to 
``uniform test method'' with ``this appendix'' (section 3.3 of appendix 
A), (vi) removing reference to guidelines under section 3.4.1, Required 
actions, of appendix A to clarify that section establishes 
requirements, (vii) specifying the maximum amount of time for the 
temperature of the transformer windings to stabilize (section 
3.2.2(b)(4) of appendix A \31\), (viii) removing references to the test 
procedure in 10 CFR 431.196, and (ix) replacing any reference to 
accuracy requirements in ``section 2.0'' and/or ``Table 2.0'' to 
``section 2.3'' and/or ``Table 2.3,'' accordingly. 84 FR 20704, 20720.
---------------------------------------------------------------------------

    \30\ Under the changes adopted in this document, section 
3.2.2(a) of appendix A is split into section 3.2.2(a) and section 
3.2.2(b).
    \31\ Under the changes adopted in this document, this section is 
redesignated as section 3.2.2(c)(4) of appendix A.
---------------------------------------------------------------------------

    Section 3.2.2 of appendix A requires that, for testing of both 
ventilated and sealed units, the ambient temperature of the test area 
may be used to estimate the winding temperature (rather than direct 
measurement of the winding temperature), provided a number of 
conditions are met, including the condition that neither voltage nor 
current has been applied to the unit under test for 24 hours (provided 
in section 3.2.2(b)(4) of appendix A). The same section also allows for 
the time period of the initial 24 hours to be increased to up to a 
maximum of an additional 24 hours, so as to allow the temperature of 
the transformer windings to stabilize at the level of the ambient 
temperature. Based on this requirement, the total amount of time 
allowed would be a maximum of 48 hours. As such, in the May 2019 NOPR, 
DOE proposed to specify explicitly that, for section 3.2.2(b)(4) of 
appendix A, the total maximum amount of time allowed is 48 hours. Id.
    DOE also proposed conforming amendments to the energy conservation 
standard provisions. The provisions in 10 CFR 431.196 establishes 
energy conservation standards for certain distribution transformers. 
Id. Immediately following each table of standards, a note specifies the 
applicable standard PUL and DOE test procedure. For example, in 10 CFR 
431.196(a) the note reads, ``Note: All efficiency values are at 35 
percent of nameplate-rated load, determined according to the DOE Test 
Method for Measuring the Energy Consumption of Distribution 
Transformers under appendix A to subpart K of 10 CFR part 431.'' 
Because 10 CFR 431.193 already requires that testing be in accordance 
with appendix A, DOE proposes to remove the references to the test 
procedure in 10 CFR 431.196. DOE proposes to maintain the portion of 
the note identifying the PUL corresponding to the efficiency values, 
for continuity and clarity. Id.
    As discussed in sections III.F.1 and III.F.2 of this final rule, 
DOE is clarifying the PUL and reference temperature specifications for 
certification to energy conservation standards, and providing PUL and 
reference temperature specifications for voluntary representations, 
with a new section 2.1 for PUL requirements and section 2.2 for 
reference temperature requirements in appendix A. Accordingly, DOE 
proposed that the accuracy requirements previously provided in section 
2.0 be moved to section 2.3 in appendix A. In addition, DOE proposed to 
re-number Table 2.1, Test System Accuracy Requirements for Each 
Measured Quantity, to Table 2.3. Lastly, DOE proposed to update cross-

[[Page 51249]]

references in appendix A to the accuracy requirements in section 2.0 
and/or Table 2.1, to section 2.3 and/or Table 2.3. The cross-references 
occur in sections 3.1(b), 3.3.3, 3.4.2(a), 4.3(a), 6.0, and 6.2 of 
appendix A.
    DOE did not receive any comment in opposition to these edits and is 
adopting them in the test procedure.
    NEMA noted certain errors in the equation references in section 4 
of appendix A. (NEMA, No. 30 at p. 5) Specifically, NEMA stated that 
the load loss power (Plc1) appears with subscripts ``LCL'', 
``LCI'', and ``LC1'' (capital letters used for clarity, but lower case 
used in the text). Id. DOE has reviewed the subscripts in section 4 of 
appendix A and corrected each instance to ``LC1'' (capitalized here for 
clarity) where necessary.
    NEMA also noted that there is potential confusion regarding which 
reference temperature should be used in section 4.5.3.3 of appendix A. 
NEMA suggested to clarify the text as follows: ``When the measurement 
of load loss is made at a temperature Tim that is different 
from the reference temperature, use the procedure summarized in the 
equations 4-6 to 4-10 to correct the measured load loss to the 
reference temperature (as defined in 3.5 (a)).'' (NEMA, No. 30 at p. 5-
6) This final rule includes a new section, section 2.2 of appendix A, 
to specify reference temperature in a centralized location, as 
described in section III.F.2 of this document. In view of the new 
requirement, NEMA's suggested edits to specify reference temperature in 
section 4.5.3.3 are redundant.
    PG&E commented in response to the May 2019 NOPR that in order to 
properly comment, it would like a before and after document of proposed 
changes to the CFR. (PG&E, No. 33 at p. 1) The May 2019 NOPR includes a 
synopsis table of the proposed changes, including a side-by-side 
comparison of the current DOE TP language, the proposed test procedure 
language, and attribution of the changes. 84 FR 20704, 20706. Further, 
DOE published all proposed regulatory text in the May 2019 NOPR which 
could be juxtaposed with the current CFR in order to perform the 
comparison PG&E describes. 84 FR 20704, 20727-20730.

G. Effective and Compliance Dates

    The effective date for the adopted test procedure amendment is 30 
days after publication of this final rule in the Federal Register. EPCA 
prescribes that all representations of energy efficiency and energy 
use, including those made on marketing materials and product labels, 
must be made in accordance with an amended test procedure, beginning 
180 days after publication of the final rule in the Federal Register. 
(42 U.S.C. 6293(c)(2); 42 U.S.C. 6314(d)(1)) EPCA provides an allowance 
for individual manufacturers to petition DOE for an extension of the 
180-day period if the manufacturer may experience undue hardship in 
meeting the deadline. (42 U.S.C. 6293(c)(3); 42 U.S.C. 6314(d)(2)) To 
receive such an extension, petitions must be filed with DOE no later 
than 60 days before the end of the 180-day period and must detail how 
the manufacturer will experience undue hardship. (Id.)

H. Test Procedure Costs

    In this final rule, DOE is amending the existing test procedure for 
distribution transformers by revising certain definitions, 
incorporating new definitions, incorporating revisions based on the 
latest versions of the IEEE industry testing standards, including 
provisions to allow manufacturers to use the DOE test procedure to make 
voluntary representations at additional PULs and/or reference 
temperatures, and reorganizing content among relevant sections of the 
CFR to improve readability. The adopted amendments primarily provide 
updates and supplemental details for how to conduct the test procedure 
and do not add complexity to test conditions/setup or add test steps. 
In accordance with EPCA, DOE has determined that these adopted 
amendments will not be unduly burdensome for manufacturers to conduct. 
Further, DOE has determined that the adopted test procedure amendments 
will not impact testing costs already experienced by manufacturers. DOE 
estimated, based on a test quote from a laboratory, that the cost for 
testing distribution transformers using the existing test procedure is 
approximately $400 per unit tested and that this figure will not change 
in response to the adopted test procedure amendments. In summary, the 
adopted test procedure amendments reflect and codify current industry 
practice.
    As previously described in the May 2019 NOPR, the adopted 
amendments will not impact the scope of the test procedure. The adopted 
amendments will not require the testing of distribution transformers 
not already subject to the test procedure at 10 CFR 431.193 (i.e., the 
adopted amendments will not require manufacturers to test 
autotransformers, drive (isolation) transformers, grounding 
transformers, machine-tool (control) transformers, nonventilated 
transformers, rectifier transformers, regulating transformers, sealed 
transformer; special-impedance transformer; testing transformer; 
transformer with tap range of 20 percent or more; uninterruptible power 
supply transformer; or welding transformer, which are presently not 
subject to testing). The adopted amendments will not alter the measured 
energy efficiency or energy use of the distribution transformers. 
Manufacturers will be able to rely on data generated under the current 
test procedure. Further, the adopted amendments will not require the 
purchase of additional equipment for testing.
    In the May 2019 NOPR, DOE described why the proposed test procedure 
amendments would not add costs to manufacturers. In response, 
manufacturers commented stating the proposed testing should not 
increase testing costs for any manufacturers. (Howard, No. 32 at p. 2; 
CDA, No. 29 at p. 3-4; HVOLT, No. 27 at p. 91-93) NEMA commented that 
it does not anticipate any negative impact or increased costs 
associated with any of the proposed changes but stressed that DOE 
continue to allow manufacturers to certify distribution transformers 
using an AEDM as is allowed at 10 CFR 429.70(d) in order to minimize 
testing costs. (NEMA, No. 30 at p. 4) DOE notes that it has not 
proposed or adopted any changes to 10 CFR 429.70(d), and manufacturers 
are permitted to use an AEDM for means of certifying distribution 
transformer efficiency to DOE.

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Order 12866

    The Office of Management and Budget (``OMB'') has determined this 
test procedure rulemaking does not constitute a ``significant 
regulatory action'' under section 3(f) of Executive Order (``E.O.'') 
12866, Regulatory Planning and Review, 58 FR 51735 (Oct. 4, 1993). 
Accordingly, this action was not subject to review under the Executive 
order by the Office of Information and Regulatory Affairs (``OIRA'') in 
OMB.

B. Review Under the Regulatory Flexibility Act

    The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires 
preparation of a final regulatory flexibility analysis (``FRFA'') for 
any final rule where the agency was first required by law to publish a 
proposed rule for public comment, unless the agency certifies that the 
rule, if promulgated, will not have a significant economic impact on a 
substantial number of small entities. As required by Executive Order 
13272,

[[Page 51250]]

``Proper Consideration of Small Entities in Agency Rulemaking,'' 67 FR 
53461 (August 16, 2002), DOE published procedures and policies on 
February 19, 2003 to ensure that the potential impacts of its rules on 
small entities are properly considered during the DOE rulemaking 
process. 68 FR 7990. DOE has made its procedures and policies available 
on the Office of the General Counsel's website: https://energy.gov/gc/office-general-counsel.
    As stated, the amendments adopted in this final rule revise certain 
definitions, incorporate new definitions, incorporate revisions based 
on the latest versions of the IEEE industry testing standards, include 
provisions to allow manufacturers to use the DOE test procedure to make 
voluntary representations at additional PULs and/or reference 
temperatures, and reorganize content among relevant sections of the CFR 
to improve readability. DOE has determined that the adopted test 
procedure amendments would not impact testing costs already experienced 
by manufacturers. NEMA, CDA, and HVOLT commented that they do not 
anticipate any undue burden on small businesses or small manufacturers. 
(NEMA, No. 30 at p. 5; CDA, No. 29 at p. 4; HVOLT, No. 27 at p. 94)
    Therefore, DOE concludes that the cost effects accruing from the 
final rule would not have a ``significant economic impact on a 
substantial number of small entities,'' and that the preparation of a 
FRFA is not warranted. DOE has submitted a certification and supporting 
statement of factual basis to the Chief Counsel for Advocacy of the 
Small Business Administration for review under 5 U.S.C. 605(b).

C. Review Under the Paperwork Reduction Act of 1995

    Manufacturers of distribution transformers must certify to DOE that 
their products comply with any applicable energy conservation 
standards. To certify compliance, manufacturers must first obtain test 
data for their products according to the DOE test procedure, including 
any amendments adopted for that test procedure. DOE has established 
regulations for the certification and recordkeeping requirements for 
all covered consumer products and commercial equipment, including 
distribution transformers. (See generally 10 CFR part 429.) The 
collection-of-information requirement for the certification and 
recordkeeping is subject to review and approval by OMB under the 
Paperwork Reduction Act (PRA). This requirement has been approved by 
OMB under OMB control number 1910-1400. Public reporting burden for the 
certification is estimated to average 35 hours per response, including 
the time for reviewing instructions, searching existing data sources, 
gathering and maintaining the data needed, and completing and reviewing 
the collection of information.
    The amendments adopted in this final rule do not impact the 
certification and reporting requirements for distribution transformers.
    Notwithstanding any other provision of the law, no person is 
required to respond to, nor shall any person be subject to a penalty 
for failure to comply with, a collection of information subject to the 
requirements of the PRA, unless that collection of information displays 
a currently valid OMB Control Number.

D. Review Under the National Environmental Policy Act of 1969

    Pursuant to the National Environmental Policy Act of 1969 
(``NEPA''), DOE has analyzed this action in accordance with NEPA and 
DOE's NEPA implementing regulations (10 CFR part 1021). DOE has 
determined that this rule qualifies for categorical exclusion under 10 
CFR part 1021, subpart D, appendix A5, because it is an interpretive 
rulemaking that does not change the environmental effect of the rule 
and meets the requirements for application of a CX. See 10 CFR 
1021.410. Therefore, DOE has determined that promulgation of this rule 
is not a major Federal action significantly affecting the quality of 
the human environment within the meaning of NEPA and does not require 
an EA or EIS.

E. Review Under Executive Order 13132

    Executive Order 13132, ``Federalism,'' 64 FR 43255 (August 4, 
1999), imposes certain requirements on agencies formulating and 
implementing policies or regulations that preempt State law or that 
have federalism implications. The Executive order requires agencies to 
examine the constitutional and statutory authority supporting any 
action that would limit the policymaking discretion of the States and 
to carefully assess the necessity for such actions. The Executive order 
also requires agencies to have an accountable process to ensure 
meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications. 
On March 14, 2000, DOE published a statement of policy describing the 
intergovernmental consultation process it will follow in the 
development of such regulations. 65 FR 13735. DOE examined this final 
rule and determined that it will not have a substantial direct effect 
on the States, on the relationship between the National Government and 
the States, or on the distribution of power and responsibilities among 
the various levels of government. EPCA governs and prescribes Federal 
preemption of State regulations as to energy conservation for the 
products that are the subject of this final rule. States can petition 
DOE for exemption from such preemption to the extent, and based on 
criteria, set forth in EPCA. (42 U.S.C. 6297(d)) No further action is 
required by Executive Order 13132.

F. Review Under Executive Order 12988

    Regarding the review of existing regulations and the promulgation 
of new regulations, section 3(a) of Executive Order 12988, ``Civil 
Justice Reform,'' 61 FR 4729 (Feb. 7, 1996), imposes on Federal 
agencies the general duty to adhere to the following requirements: (1) 
Eliminate drafting errors and ambiguity; (2) write regulations to 
minimize litigation; (3) provide a clear legal standard for affected 
conduct rather than a general standard; and (4) promote simplification 
and burden reduction. Section 3(b) of Executive Order 12988 
specifically requires that executive agencies make every reasonable 
effort to ensure that the regulation (1) clearly specifies the 
preemptive effect, if any; (2) clearly specifies any effect on existing 
Federal law or regulation; (3) provides a clear legal standard for 
affected conduct while promoting simplification and burden reduction; 
(4) specifies the retroactive effect, if any; (5) adequately defines 
key terms; and (6) addresses other important issues affecting clarity 
and general draftsmanship under any guidelines issued by the Attorney 
General. Section 3(c) of Executive Order 12988 requires executive 
agencies to review regulations in light of applicable standards in 
sections 3(a) and 3(b) to determine whether they are met, or it is 
unreasonable to meet one or more of them. DOE has completed the 
required review and determined that, to the extent permitted by law, 
this final rule meets the relevant standards of Executive Order 12988.

G. Review Under the Unfunded Mandates Reform Act of 1995

    Title II of the Unfunded Mandates Reform Act of 1995 (``UMRA'') 
requires each Federal agency to assess the effects of Federal 
regulatory actions on State, local, and Tribal governments, and the 
private sector. Public Law 104-4, sec. 201 (codified at 2 U.S.C. 1531). 
For a regulatory action resulting in a rule that

[[Page 51251]]

may cause the expenditure by State, local, and Tribal governments, in 
the aggregate, or by the private sector of $100 million or more in any 
one year (adjusted annually for inflation), section 202 of UMRA 
requires a Federal agency to publish a written statement that estimates 
the resulting costs, benefits, and other effects on the national 
economy. (2 U.S.C. 1532(a), (b)) The UMRA also requires a Federal 
agency to develop an effective process to permit timely input by 
elected officers of State, local, and Tribal governments on a proposed 
``significant intergovernmental mandate,'' and requires an agency plan 
for giving notice and opportunity for timely input to potentially 
affected small governments before establishing any requirements that 
might significantly or uniquely affect small governments. On March 18, 
1997, DOE published a statement of policy on its process for 
intergovernmental consultation under UMRA. 62 FR 12820; also available 
at https://energy.gov/gc/office-general-counsel. DOE examined this 
final rule according to UMRA and its statement of policy and determined 
that the rule contains neither an intergovernmental mandate, nor a 
mandate that may result in the expenditure of $100 million or more in 
any year, so these requirements do not apply.

H. Review Under the Treasury and General Government Appropriations Act, 
1999

    Section 654 of the Treasury and General Government Appropriations 
Act, 1999 (Pub. L. 105-277) requires Federal agencies to issue a Family 
Policymaking Assessment for any rule that may affect family well-being. 
This final rule will not have any impact on the autonomy or integrity 
of the family as an institution. Accordingly, DOE has concluded that it 
is not necessary to prepare a Family Policymaking Assessment.

I. Review Under Executive Order 12630

    DOE has determined, under Executive Order 12630, ``Governmental 
Actions and Interference with Constitutionally Protected Property 
Rights'' 53 FR 8859 (March 18, 1988), that this regulation will not 
result in any takings that might require compensation under the Fifth 
Amendment to the U.S. Constitution.

J. Review Under Treasury and General Government Appropriations Act, 
2001

    Section 515 of the Treasury and General Government Appropriations 
Act, 2001 (44 U.S.C. 3516 note) provides for agencies to review most 
disseminations of information to the public under guidelines 
established by each agency pursuant to general guidelines issued by 
OMB. OMB's guidelines were published at 67 FR 8452 (Feb. 22, 2002), and 
DOE's guidelines were published at 67 FR 62446 (Oct. 7, 2002). Pursuant 
to OMB Memorandum M-19-15, Improving Implementation of the Information 
Quality Act (April 24, 2019), DOE published updated guidelines which 
are available at www.energy.gov/sites/prod/files/2019/12/f70/DOE%20Final%20Updated%20IQA%20Guidelines%20Dec%202019.pdf. DOE has 
reviewed this final rule under the OMB and DOE guidelines and has 
concluded that it is consistent with applicable policies in those 
guidelines.

K. Review Under Executive Order 13211

    Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use,'' 66 FR 28355 
(May 22, 2001), requires Federal agencies to prepare and submit to OMB, 
a Statement of Energy Effects for any significant energy action. A 
``significant energy action'' is defined as any action by an agency 
that promulgated or is expected to lead to promulgation of a final 
rule, and that (1) is a significant regulatory action under Executive 
Order 12866, or any successor order; and (2) is likely to have a 
significant adverse effect on the supply, distribution, or use of 
energy; or (3) is designated by the Administrator of OIRA as a 
significant energy action. For any significant energy action, the 
agency must give a detailed statement of any adverse effects on energy 
supply, distribution, or use if the regulation is implemented, and of 
reasonable alternatives to the action and their expected benefits on 
energy supply, distribution, and use.
    This regulatory action is not a significant regulatory action under 
Executive Order 12866. Moreover, it would not have a significant 
adverse effect on the supply, distribution, or use of energy, nor has 
it been designated as a significant energy action by the Administrator 
of OIRA. Therefore, it is not a significant energy action, and, 
accordingly, DOE has not prepared a Statement of Energy Effects.

L. Review Under Section 32 of the Federal Energy Administration Act of 
1974

    Under section 301 of the Department of Energy Organization Act 
(Pub. L. 95-91; 42 U.S.C. 7101), DOE must comply with section 32 of the 
Federal Energy Administration Act of 1974, as amended by the Federal 
Energy Administration Authorization Act of 1977. (15 U.S.C. 788; 
``FEAA'') Section 32 essentially provides in relevant part that, where 
a proposed rule authorizes or requires use of commercial standards, the 
notice of proposed rulemaking must inform the public of the use and 
background of such standards. In addition, section 32(c) requires DOE 
to consult with the Attorney General and the Chairman of the Federal 
Trade Commission (``FTC'') concerning the impact of the commercial or 
industry testing standards on competition.
    The modifications to the test procedure for distribution 
transformers adopted in this final rule do not incorporate testing 
methods contained in commercial standards. Therefore, the requirements 
of section 32(b) of the FEAA do not apply.

M. Congressional Notification

    As required by 5 U.S.C. 801, DOE will report to Congress on the 
promulgation of this rule before its effective date. The report will 
state that it has been determined that the rule is not a ``major rule'' 
as defined by 5 U.S.C. 804(2).

V. Approval of the Office of the Secretary

    The Secretary of Energy has approved publication of this final 
rule.

List of Subjects in 10 CFR Part 431

    Administrative practice and procedure, Confidential business 
information, Energy conservation test procedures, and Reporting and 
recordkeeping requirements.

Signing Authority

    This document of the Department of Energy was signed on September 
2, 2021, by Kelly Speakes-Backman, Principal Deputy Assistant Secretary 
and Acting Assistant Secretary for Energy Efficiency and Renewable 
Energy, pursuant to delegated authority from the Secretary of Energy. 
That document with the original signature and date is maintained by 
DOE. For administrative purposes only, and in compliance with 
requirements of the

[[Page 51252]]

Office of the Federal Register, the undersigned DOE Federal Register 
Liaison Officer has been authorized to sign and submit the document in 
electronic format for publication, as an official document of the 
Department of Energy. This administrative process in no way alters the 
legal effect of this document upon publication in the Federal Register.

    Signed in Washington, DC, on September 2, 2021.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.

    For the reasons stated in the preamble, DOE amends part 431 of 
chapter II of title 10, Code of Federal Regulations as set forth below:

PART 431--ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND 
INDUSTRIAL EQUIPMENT

0
1. The authority citation for part 431 continues to read as follows:

    Authority: 42 U.S.C. 6291-6317; 28 U.S.C. 2461 note.


0
2. Section 431.192 is amended by:
0
a. Adding in alphabetical order the definition for Auxiliary device;
0
b. Revising the definition of Low-voltage dry-type distribution 
transformer;
0
c. Adding in alphabetical order the definition for Per-unit load;
0
d. Revising the definition of Reference temperature; and
0
e. Adding in alphabetical order the definition for Terminal.
    The additions and revisions read as follows:


Sec.  431.192   Definitions.

* * * * *
    Auxiliary device means a localized component of a distribution 
transformer that is a circuit breaker, switch, fuse, or surge/lightning 
arrester.
* * * * *
    Low-voltage dry-type distribution transformer means a distribution 
transformer that has an input voltage of 600 volts or less and has the 
core and coil assembly immersed in a gaseous or dry-compound insulating 
medium.
* * * * *
    Per-unit load means the fraction of rated load.
* * * * *
    Reference temperature means the temperature at which the 
transformer losses are determined, and to which such losses are 
corrected if testing is done at a different point. (Reference 
temperature values are specified in the test method in appendix A to 
this subpart.)
* * * * *
    Terminal means a conducting element of a distribution transformer 
providing electrical connection to an external conductor that is not 
part of the transformer.
* * * * *

0
3. Section 431.193 is revised to read as follows:


Sec.  431.193  Test procedure for measuring energy consumption of 
distribution transformers.

    The test procedure for measuring the energy efficiency of 
distribution transformers for purposes of EPCA is specified in appendix 
A to this subpart. The test procedure specified in appendix A to this 
subpart applies only to distribution transformers subject to energy 
conservation standards at Sec.  431.196.

0
4. Section 431.196 is amended by revising the Notes in paragraphs 
(a)(1) and (2), (b)(1) and (2), and (c)(1) and (2) to read as follows:


Sec.  431.196  Energy conservation standards and their effective dates.

    (a) * * *
    (1) * * *

    Note 1 to paragraph (a)(1):  All efficiency values are at 35 
percent per-unit load.

    (2) * * *

    Note 2 to paragraph (a)(2): All efficiency values are at 35 
percent per-unit load.

    (b) * * *
    (1) * * *

    Note 3 to paragraph (b)(1):  All efficiency values are at 50 
percent per-unit load.

    (2) * * *

    Note 4 to paragraph (b)(2):  All efficiency values are at 50 
percent per-unit load.

    (c) * * *
    (1) * * *

    Note 5 to paragraph (c)(1): All efficiency values are at 50 
percent per-unit load.

    (2) * * *

    Note 6 to paragraph (c)(2):  All efficiency values are at 50 
percent per-unit load.

* * * * *

0
5. Appendix A to subpart K of part 431 is amended by:
0
a. In section 2.0:
0
i. Revising the section heading;
0
ii. Removing paragraphs (a) and (b); and
0
iii. Adding sections 2.1, 2.2, and 2.3;
0
b. Adding paragraph (c) to section 3.1;
0
c. Revising section 3.2.1.1;
0
d. Revising paragraph (b) in section 3.2.1.2;
0
e. Revising section 3.2.2;
0
f. Revising section 3.3;
0
g. Revising paragraph (a) introductory text and paragraph (b) in 
section 3.3.2;
0
h. Revising section 3.3.3;
0
i. Revising the introductory text and adding paragraphs (f), (g), (h), 
and (i) in section 3.4.1;
0
j. Revising paragraph (a) in section 3.4.2;
0
k. Revising paragraph (a) in section 3.5;
0
l. Revising section 4.1;
0
m. Revising paragraph (a) and adding paragraph (c) in section 4.3;
0
n. Revising section 4.4.3.3;
0
o. Revising paragraph (c) of section 4.5.3.2;
0
p. Revising section 5.1;
0
q. Revising section 6.0;
0
r. Revising section 6.1;
0
s. Revising paragraph (a) in section 6.2; and
0
t. Adding section 7.0.
    The additions and revisions read as follows:

Appendix A to Subpart K of Part 431--Uniform Test Method for Measuring 
the Energy Consumption of Distribution Transformers

* * * * *

2.0 Per-Unit Load, Reference Temperature, and Accuracy Requirements

2.1 Per-Unit Load

    In conducting the test procedure in this appendix for the 
purpose of:
    (a) Certification to an energy conservation standard, the 
applicable per-unit load in Table 2.1 must be used; or
    (b) Making voluntary representations as provided in section 7.0 
at an additional per-unit load, select the per-unit load of 
interest.

    Table 2.1--Per-unit Load for Certification to Energy Conservation
                                Standards
------------------------------------------------------------------------
                                                               Per-unit
              Distribution transformer category                  load
                                                               (percent)
------------------------------------------------------------------------
Liquid-immersed.............................................          50
Medium-voltage dry-type.....................................          50
Low-voltage dry-type........................................          35
------------------------------------------------------------------------

2.2 Reference Temperature

    In conducting the test procedure in this appendix for the 
purpose of:
    (a) Certification to an energy conservation standard, the 
applicable reference temperature in Table 2.2 must be used; or
    (b) Making voluntary representations as provided in section 7.0 
at an additional reference temperature, select the reference 
temperature of interest.

[[Page 51253]]



      Table 2.2--Reference Temperature for Certification to Energy
                         Conservation Standards
------------------------------------------------------------------------
     Distribution transformer category          Reference temperature
------------------------------------------------------------------------
Liquid-immersed...........................  20 [deg]C for no-load loss.
                                            55 [deg]C for load loss.
Medium-voltage dry-type...................  20 [deg]C for no-load loss.
                                            75 [deg]C for load loss.
Low-voltage dry-type......................  20 [deg]C for no-load loss.
                                            75 [deg]C for load loss.
------------------------------------------------------------------------

2.3 Accuracy Requirements

    (a) Equipment and methods for loss measurement must be 
sufficiently accurate that measurement error will be limited to the 
values shown in Table 2.3.

 Table 2.3--Test System Accuracy Requirements for Each Measured Quantity
------------------------------------------------------------------------
          Measured quantity                   Test system accuracy
------------------------------------------------------------------------
Power Losses.........................  3.0%.
Voltage..............................  0.5%.
Current..............................  0.5%.
Resistance...........................  0.5%.
Temperature..........................  1.5 [deg]C for liquid-
                                        immersed distribution
                                        transformers, and 2.0 [deg]C for low-voltage
                                        dry-type and medium-voltage dry-
                                        type distribution transformers.
------------------------------------------------------------------------

    (b) Only instrument transformers meeting the 0.3 metering 
accuracy class, or better, may be used under this test method.

3.0 * * *

3.1 General Considerations

* * * * *
    (c) Measure the direct current resistance (Rdc) of 
transformer windings by one of the methods outlined in section 3.3. 
The methods of section 3.5 must be used to correct load losses to 
the applicable reference temperature from the temperature at which 
they are measured. Observe precautions while taking measurements, 
such as those in section 3.4, in order to maintain measurement 
uncertainty limits specified in Table 2.3 of this appendix.
* * * * *

3.2.1.1 Methods

    Record the winding temperature (Tdc) of liquid-
immersed transformers as the average of either of the following:
    (a) The measurements from two temperature sensing devices (for 
example, thermocouples) applied to the outside of the transformer 
tank and thermally insulated from the surrounding environment, with 
one located at the level of the insulating liquid and the other 
located near the tank bottom or at the lower radiator header if 
applicable; or
    (b) The measurements from two temperature sensing devices 
immersed in the insulating liquid, with one located directly above 
the winding and other located directly below the winding.

3.2.1.2 Conditions

* * * * *
    (b) The temperature of the insulating liquid has stabilized, and 
the difference between the top and bottom temperature does not 
exceed 5 [deg]C. The temperature of the insulating liquid is 
considered stable if the top liquid temperature does not vary more 
than 2 [deg]C in a 1-h period.

3.2.2 Dry-Type Distribution Transformers

    Record the winding temperature (Tdc) of dry-type 
transformers as one of the following:
    (a) For ventilated dry-type units, use the average of readings 
of four or more thermometers, thermocouples, or other suitable 
temperature sensors inserted within the coils. Place the sensing 
points of the measuring devices as close as possible to the winding 
conductors; or
    (b) For sealed units, such as epoxy-coated or epoxy-encapsulated 
units, use the average of four or more temperature sensors located 
on the enclosure and/or cover, as close to different parts of the 
winding assemblies as possible; or
    (c) For ventilated units or sealed units, use the ambient 
temperature of the test area, only if the following conditions are 
met:
    (1) All internal temperatures measured by the internal 
temperature sensors must not differ from the test area ambient 
temperature by more than 2 [deg]C. Enclosure surface temperatures 
for sealed units must not differ from the test area ambient 
temperature by more than 2 [deg]C.
    (2) Test area ambient temperature must not have changed by more 
than 3 [deg]C for 3 hours before the test.
    (3) Neither voltage nor current has been applied to the unit 
under test for 24 hours. In addition, increase this initial 24-hour 
period by any added amount of time necessary for the temperature of 
the transformer windings to stabilize at the level of the ambient 
temperature. However, this additional amount of time need not exceed 
24 hours (i.e., after 48 hours, the transformer windings can be 
assumed to have stabilized at the level of the ambient temperature. 
Any stabilization time beyond 48 hours is optional).

3.3 Resistance Measurement Methods

    Make resistance measurements using either the resistance bridge 
method (section 3.3.1), the voltmeter-ammeter method (section 3.3.2) 
or resistance meters (section 3.3.3). In each instance when this 
appendix is used to test more than one unit of a basic model to 
determine the efficiency of that basic model, the resistance of the 
units being tested may be determined from making resistance 
measurements on only one of the units.
* * * * *

3.3.2 Voltmeter-Ammeter Method

    (a) Employ the voltmeter-ammeter method only if the test current 
is limited to 15 percent of the winding current. Connect the 
transformer winding under test to the circuit shown in Figure 3.3 of 
this appendix.
* * * * *
    (b) To perform the measurement, turn on the source to produce 
current no larger than 15 percent of the rated current for the 
winding. Wait until the current and voltage readings have stabilized 
and then take a minimum of four readings of voltage and current. 
Voltage and current readings must be taken simultaneously for each 
of the readings. Calculate the average voltage and average current 
using the readings. Determine the winding resistance Rdc 
by using equation 3-4 as follows:
[GRAPHIC] [TIFF OMITTED] TR14SE21.014

Where:

Vmdc is the average voltage measured by the voltmeter V; 
and
Imdc is the average current measured by the ammeter (A).
* * * * *

3.3.3 Resistance Meters

    Resistance meters may be based on voltmeter-ammeter, or 
resistance bridge, or some other operating principle. Any meter used 
to measure a transformer's winding resistance must have 
specifications for resistance range, current range, and ability to 
measure highly inductive resistors that cover the characteristics of 
the transformer being tested. Also, the meter's specifications for 
accuracy must meet the applicable criteria of Table 2.3 in section 
2.3 of this appendix.
* * * * *

3.4.1 Required Actions

    The following requirements must be observed when making 
resistance measurements:
* * * * *
    (f) Keep the polarity of the core magnetization constant during 
all resistance measurements.
    (g) For single-phase windings, measure the resistance from 
terminal to terminal. The total winding resistance is the terminal-
to-terminal measurement. For series-parallel windings, the total 
winding resistance is the sum of the series terminal-to-terminal 
section measurements.
    (h) For wye windings, measure the resistance from terminal to 
terminal or from terminal to neutral. For the total winding 
resistance, the resistance of the lead from the neutral connection 
to the neutral bushing may be excluded. For terminal-to-terminal 
measurements, the total resistance reported is the sum of the three 
measurements divided by two.
    (i) For delta windings, measure resistance from terminal to 
terminal with the delta closed or from terminal to terminal with the

[[Page 51254]]

delta open to obtain the individual phase readings. The total 
winding resistance is the sum of the three-phase readings if the 
delta is open. If the delta is closed, the total winding resistance 
is the sum of the three phase-to-phase readings times 1.5.

3.4.2 Guideline for Time Constant

    (a) The following guideline is suggested for the tester as a 
means to facilitate the measurement of resistance in accordance with 
the accuracy requirements of section 2.3:
* * * * *

3.5 Conversion of Resistance Measurements

    (a) Resistance measurements must be corrected from the 
temperature at which the winding resistance measurements were made, 
to the reference temperature.
* * * * *

4.0 * * *

4.1 General Considerations

    The efficiency of a transformer is computed from the total 
transformer losses, which are determined from the measured value of 
the no-load loss and load loss power components. Each of these two 
power loss components is measured separately using test sets that 
are identical, except that shorting straps are added for the load-
loss test. The measured quantities need correction for 
instrumentation losses and may need corrections for known phase 
angle errors in measuring equipment and for the waveform distortion 
in the test voltage. Any power loss not measured at the applicable 
reference temperature must be adjusted to that reference 
temperature. The measured load loss must also be adjusted to a 
specified output loading level if not measured at the specified 
output loading level. Test all distribution transformers using a 
sinusoidal waveform (k = 1). Measure losses with the transformer 
energized by a 60 Hz supply.
* * * * *

4.3 Test Sets

    (a) The same test set may be used for both the no-load loss and 
load loss measurements provided the range of the test set 
encompasses the test requirements of both tests. Calibrate the test 
set to national standards to meet the tolerances in Table 2.3 in 
section 2.3 of this appendix. In addition, the wattmeter, current 
measuring system and voltage measuring system must be calibrated 
separately if the overall test set calibration is outside the 
tolerance as specified in section 2.3 or the individual phase angle 
error exceeds the values specified in section 4.5.3.
* * * * *
    (c) Both load loss and no-load loss measurements must be made 
from terminal to terminal.
* * * * *

4.4.3.3 Correction of No-Load Loss to Reference Temperature

    After correcting the measured no-load loss for waveform 
distortion, correct the loss to the reference temperature. For both 
certification to energy conservation standards and voluntary 
representations, if the correction to reference temperature is 
applied, then the core temperature of the transformer during no-load 
loss measurement (Tnm) must be determined within 10 [deg]C of the true average core temperature. For 
certification to energy conservation standards only, if the no-load 
loss measurements were made between 10 [deg]C and 30 [deg]C, this 
correction is not required. Correct the no-load loss to the 
reference temperature by using equation 4-2 as follows:
[GRAPHIC] [TIFF OMITTED] TR14SE21.015

Where:

Pnc is the no-load losses corrected for waveform distortion and then 
to the reference temperature;
Pnc1 is the no-load losses, corrected for waveform distortion, at 
temperature Tnm;
Tnm is the core temperature during the measurement of no-load 
losses; and
Tnr is the reference temperature.
* * * * *

4.5.3.2 Correction for Phase Angle Errors

* * * * *
    (c) If the correction for phase angle errors is to be applied, 
first examine the total system phase angle ([beta]w-
[beta]v + [beta]c). Where the total system 
phase angle is equal to or less than 12 milliradians 
(41 minutes), use either equation 4-4 or 4-5 to correct 
the measured load loss power for phase angle errors, and where the 
total system phase angle exceeds 12 milliradians (41 minutes) use equation 4-5, as follows:
[GRAPHIC] [TIFF OMITTED] TR14SE21.016

* * * * *

5.0 * * *

5.1 Output Loading Level Adjustment

    If the per-unit load selected in section 2.1 is different from 
the per-unit load at which the load loss power measurements were 
made, then adjust the corrected load loss power, Plc2, by 
using equation 5-1 as follows:
[GRAPHIC] [TIFF OMITTED] TR14SE21.017

Where:

Plc is the adjusted load loss power to the per-unit load;
Plc2 is as calculated in section 4.5.3.3;
Por is the rated transformer apparent power (name plate);
Pos is the adjusted rated transformer apparent power, where Pos = 
PorL; and
L is the per-unit load, e.g., if the per-unit load is 50 percent 
then ``L'' is 0.5.
* * * * *

6.0 Test Equipment Calibration and Certification

    Maintain and calibrate test equipment and measuring instruments, 
maintain calibration records, and perform other test and measurement 
quality assurance procedures according to the following sections. 
The calibration of the test set must confirm the accuracy of the 
test set to that specified in section 2.3, Table 2.3 of this 
appendix.

6.1 Test Equipment

    The party performing the tests must control, calibrate, and 
maintain measuring and test equipment, whether or not it owns the 
equipment, has the equipment on loan, or the equipment is provided 
by another party. Equipment must be used in a manner which assures 
that measurement uncertainty is known and is consistent with the 
required measurement capability.

6.2 Calibration and Certification

* * * * *

[[Page 51255]]

    (a) Identify the measurements to be made, the accuracy required 
(section 2.3) and select the appropriate measurement and test 
equipment;
* * * * *

7.0 Test Procedure for Voluntary Representations

    Follow sections 1.0 through 6.0 of this appendix using the per-
unit load and/or reference temperature of interest for voluntary 
representations of efficiency, and corresponding values of load loss 
and no-load loss at additional per-unit load and/or reference 
temperature. Representations made at a per-unit load and/or 
reference temperature other than those required to comply with the 
energy conservation standards at Sec.  431.196 must be in addition 
to, and not in place of, a representation at the required DOE 
settings for per-unit load and reference temperature. As a best 
practice, the additional settings of per-unit load and reference 
temperature should be provided with the voluntary representations.

[FR Doc. 2021-19366 Filed 9-13-21; 8:45 am]
BILLING CODE 6450-01-P