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New DOE requirements for transformers
Energy Conservation Program of the Department of Energy
The target of the Energy Policy and Conservation Act
of 1975 (EPCA) is to save energy in various consumer
products and certain commercial and industrial equipment, including distribution transformers. A new rule
will become effective as of 1st of January 2016 with
even stricter energy conservation standards than its
predecessor in 2010.
General information
Name of the rule:
10 CFR Part 431 Energy Conservation Program: Energy
Conservation Standards for Distribution Transformers;
­Final Rule
Scope of application:
Distribution transformers up to 2,500 kVA
Contents: The Rule defines a framework for the requirements for the environmentally-friendly design of energy
consumption-relevant products. The objectives include
­improved energy efficiency and a general environmental
compatibility and thus the reduction of CO2 emissions.
The maximum energy efficiency determined by DOE that
is technologically feasible and economically justified shall
be achieved. The Rule applies to all transformers manu­
factured in or imported into the United States of America
after January 1st, 2016. DOE also added that they will
monitor the market for electrical steel and determine
in 2016 if even higher standards will be implemented
in future efficiency standards for cast resin transformers.
Exceptions: The term “distribution transformer” does not
include a transformer that is an
• Autotransformer
• Drive (isolation) transformer
• Grounding transformer
• Machine-tool (control) transformer
• Non-ventilated transformer
• Rectifier transformer
• Regulating transformer
• Sealed transformer
• Special-impedance transformer
• Testing transformer
• Transformer with tap range of 20 percent or more
• Uninterruptible power supply transformer
• Welding transformer
Changes for operators/transformer buyers
All distribution transformers delivered to the US after
­January 1st will need to comply to the new rule of the
DOE. Siemens has taken care of this and is able to provide
the complete range of distribution transformers according
to the new standards – liquid-immersed as well as castresin-design. Our processes and designs are adapted
­according the new standard, so that the loss levels at no
load and under load will be reached or even outperformed
if required by customers.
However, the new efficiency standards could result
in higher transformer prices due to additional material.
Also the weights and dimensions might increase which
might have an impact on the design of pad dimensions
or pole-type mounting.
We always aim to design and manufacture cost effective
transformers that not only are offered at a low base price,
but also pay off during their lifetime by saving energy.
This is why we offer an efficiency calculator for mobile
­devices (http://www.energy.siemens.com/hq/en/powertransmission/transformers/siemens-transformer-­
calculator.htm) that helps calculating the efficiency and
costeffectiveness of transformers over a certain depreciation period.
Efficiency standards for dry type
transformers
Efficiency standards for liquid immersed
distribution transformers
The efficiency of a cast resin distribution transformer
manufactured on or after January 1, 2016, shall be no less
than that required for their kVA rating in the tables below.
Cast resin distribution transformers with kVA ratings not
appearing in the table shall have their minimum efficiency
level determined by linear interpolation of the kVA and
­efficiency values immediately above and below that kVA
rating.
The efficiency of a liquid-immersed distribution trans­
former manufactured on or after January 1, 2016, shall
be no less than that required for their kVA rating in the
­tables below. Liquid-immersed distribution transformers
with kVA ratings not appearing in the table shall have
their minimum efficiency level determined by linear interpolation of the kVA and efficiency values immediately
above and below that kVA rating.
Single-phase
kVA
Single-phase
BIL*
Efficiency
20–45 kV
46–95 kV
≥96 kV
%
15
98.10
97.86
–
25
98.33
98.12
–
37.50
98.49
98.30
–
50
98.60
98.42
–
75
98.73
98.57
98.53
100
98.82
98.67
98.63
167
98.96
98.83
98.80
250
99.07
98.95
98.91
333
99.14
99.03
98.99
500
99.22
99.12
99.09
667
99.27
99.18
99.15
833
99.31
99.23
99.20
Three-phase
kVA
BIL*
Efficiency
20–45 kV
46–95 kV
≥96 kV
%
15
97.50
97.18
–
30
97.90
97.63
–
45
98.10
97.86
–
75
98.33
98.13
–
112.50
98.52
98.36
–
150
98.65
98.51
–
225
98.82
98.69
98.57
300
98.93
98.81
98.69
500
99.09
98.99
98.89
750
99.21
99.12
99.02
1000
99.28
99.20
99.11
1500
99.37
99.30
99.21
2000
99.43
99.36
99.28
2500
99.47
99.41
99.33
Three-phase
Rating
Efficiency
Rating
Efficiency
kVA
%
kVA
%
10
98.70
15
98.65
15
98.82
30
98.83
25
98.95
45
98.92
37.50
99.05
75
99.03
99.11
50
99.11
112.50
75
99.19
150
99.16
100
99.25
225
99.23
167
99.33
300
99.27
250
99.39
500
99.35
333
99.43
750
99.40
500
99.49
1000
99.43
667
99.52
1500
99.48
833
99.55
2000
99.51
2500
99.53
Comparison 2016 to 2010:
Efficiency standards for dry type transformers
Three-phase 2016
Rating
Three-phase 2010
Efficiency
Increasing Difference
20–45 kV
46–95 kV
98.65
98.51
kVA
150
≥96 kV
20–45 kV
46–95 kV
–
98.60
98.42
%
≥96 kV
%
%
–
0.05
0.09
–
225
98.82
98.69
98.57
98.73
98.57
98.53
0.09
0.12
0.04
300
98.93
98.81
98.69
98.82
98.67
98.63
0.11
0.14
0.06
500
99.09
98.99
98.89
98.96
98.83
98.80
0.13
0.16
0.09
750
99.21
99.12
99.02
99.07
98.95
98.91
0.14
0.17
0.11
1000
99.28
99.20
99.11
99.14
99.03
98.99
0.14
0.17
0.12
1500
99.37
99.30
99.21
99.22
99.12
99.09
0.15
0.18
0.12
2000
99.43
99.36
99.28
99.27
99.18
99.15
0.16
0.18
0.13
2500
99.47
99.41
99.33
99.31
99.23
99.20
0.16
0.18
0.13
Comparison 2016 to 2010:
Efficiency standards for liquid immersed distribution transformers
Three-phase
Rating
[kVA]
DOE 2016
Efficiency
[%]
DOE 2010
Efficiency
[%]
Increase
[%]
Three-phase
Rating
[kVA]
DOE 2016
Efficiency
[%]
DOE 2010
Efficiency
[%]
Increase
[%]
15
98.65
98.36
0.29
300
99.27
99.23
0.04
30
98.83
98.62
0.21
500
99.35
99.25
0.10
45
98.92
98.76
0.16
750
99.40
99.32
0.08
75
99.03
98.91
0.12
1000
99.43
99.36
0.07
112.50
99.11
99.01
0.10
1500
99.48
99.42
0.06
150
99.16
99.08
0.08
2000
99.51
99.46
0.05
225
99.23
99.17
0.06
2500
99.53
99.49
0.04
2000
99.51
99.46
0.05
–
–
–
–
2500
99.53
99.49
0.04
–
–
–
–
*BIL means basic impulse insulation level.
Note: all efficiency values are at 50 percent of nameplate rated load, determined acc. to the DOE Test Methold for Measuring
the Energy Consumption of Distribution Transformers under appendix A to Subpart K of 10 CFR part 431.
Frequently asked questions
How does this impact transformer
manufacturers?
Beginning January 2016, distribution
transformers imported into or manu­
factured for use in the United States of
America must comply with the requirements in the new rule if they fall within
its scope of applicability.
How does this affect existing product or
product intended for use outside the US?
The aforementioned guideline does not
apply to products manufactured for export
to other countries. Products a
­ lready in
circulation and in operation may continue
to be operated.
Who is responsible for compliance?
The party seeking to introduce the product to the United States is responsible.
This is either the manufacturer, its representative or the product importer.
Who reviews compliance with the
regulations?
Each manufacturer, its representative,
or product importer must register with
the DOE and submit performance data
to prove compliance. More information
is available at the following DOE website:
https://www.regulations.doe.gov/ccms/
registration-and-authorization-forms
Can Siemens fulfill the requirements?
In the past years, Siemens has designed
and produced transformers that already
comply with the new rule. We have done
this by using new materials such as amorphous laminations in distribution transformers, whereby more energy-efficient
transformers can be designed and manufactured.
In addition, the method of loss evaluation used for many years for defining
­individual, economically ideal solutions
has proven itself. It should, therefore,
still apply.
What effects does the guideline have
on the transformer design?
Potential effects can lead to larger
or heavier transformers, more costly
­depending on design and to a greater
use of higher-quality electrical sheets.
It is, however, important that all legal
­requirements can be implemented now
with the design concepts and materials
available in the industry.
Questions about the DOE rule?
If you have questions regarding this
rule or its implementation and fulfillment, please contact your partner
at Siemens.
Published by and copyright © 2015:
Siemens AG
Energy Management Division
Freyeslebenstrasse 1
91058 Erlangen, Germany
Siemens AG
Transformers
Katzwanger Strasse 150
90461 Nuremberg, Germany
www.siemens.com/energy
Printed in Germany
TH 101-150319 DB 0715
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