AGENDA

DEPARTMENT OF ENERGY,

WORKSHOP ON

TEST PROCEDURES FOR DISTRIBUTION TRANSFORMERS

February 10, 1998

Purpose of Workshop The purpose of the workshop is to discuss the draft test procedure

for distribution transformers and the issues surrounding it. The

Department will consider the views presented and the comments

submitted in formulating its proposed rule for distribution

transformer test procedures.

9:00 - 9:10 OPENING REMARKS AND INTRODUCTIONS

9:10 - 9:25 OVERVIEW OF THE RULEMAKING PROCESS

9:25 - 9:35 AGENDA REVIEW

TOPICS

9:35 - 10: 20 Adoption (incorporation by reference) of national and international

consensus standards in the test procedures for determining energy efficiency

of distribution transformers:

• ANSI C57.12.90-1993, "IEEE Standards Test Code for Liquid-Immersed Distribution,

Power and Regulating Transformers and IEEE Guide for Short Circuit Testing of

Distribution and Power Transformers"

• ANSI C57.12.91-1995, "IEEE Standard Test Code for Dry-Type Distribution and Power

Transformers."

• ANSI C57.12.00-1993, "IEEE Standard General requirements for Liquid -Immersed

Distribution, Power and Regulating Transformers"

• ANSI C57. 12.01-1989, "IEEE Standard General Requirements for Dry-Type Distribution

and Power Transformers, Including Those with Solid'Cast and /or Resin-Encapsulated

Windings"

• NEMA TP 1-1996, "Guide for Determining Energy Efficiency for Distribution

Transformers"

• A single clause, 4.11.1, from ISO Standard 9001-1993, "Quality Systems - Model for

quality assurance in design, development, production, installation, and servicing"

• IEEE PC57.123, "Draft Guide for Transformer Loss Measurement"

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Questions and Request for Comments

(1) Are these consensus standards appropriate for referencing in the DOE-required test

practice?

(2) Is the clause-by-clause referencing of ANSI standards in draft 5 of "Test Procedure for

Distribution Transformers," pp. 16 - 20, too detailed? Should such referencing be

abbreviated by referencing only the appropriate sections in the two test codes-those

describing dc resistance, no-load loss, and load loss measurements-and by alluding to the

specific clauses where exceptions are made?

(3) Should additional relevant standards now in preparation and approval stages, such as

IEEE PC57.123/D 1.1 "Draft Guide for Transformer Loss Measurement" and

NEMA TP-2 be considered as additional or alternative references? Will such standards

add to the knowledge base of the already existing consensus standards and

enhance the user convenience?

10:20 - 10: 30 Break

10:30 - 11:00 Definition of "basic model " for distribution transformers.

DOE is considering the following definition for "basic model" regarding transformers:

"Basic model means all units of a given type of covered equipment (or class thereof)

manufactured by a single manufacturer and, with respect to distribution transformers, which have

the same rating, have electrical characteristics that are essentially identical, and do not have any

differing physical or electrical characteristics which affect energy consumption or efficiency."

Questions and Request for Comments

(1) In view of such a definition for a "basic model," do you anticipate significant difficulties in

grouping your products into basic models?

(2) For those manufacturers having only a few items per model, would it be possible to

combine a number of models into families of basic models, e.g., grouping many actual

production models of the same nominal kVA rating in one family of models?

(3) Would it be possible to combine similar manufacturing models, e.g., having the same

nominal kVA rating, in one "basic model" by using normalized loss data?

11:00 - 12:00 Sampling plan for units to be tested.

At this time DOE is considering one of two sampling plans for compliance testing:

1) The plan described in §430.23, using the lower 95 percent confidence limit, but without

specifying the minimum number of units in the sample (A minimum of two units is implicitly

required to estimate the confidence limit.) The "K" factor, based on the six percent loss

tolerance specified in ANSI C57.12.00 and C57.12.01, is selected to be 0.999.

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2) A modified version of the proposed sampling plan for enforcement testing of motors as

outlined in 61 FR 60474 - 60475, Appendix B to Subpart G of Part 431, "Sampling Plan for

Enforcement Testing," is considered for compliance testing of distribution transformers. The

considered modification consists of replacing the factor (120 - 0.2 SFE)/SFE(20 - 0.2 SFE) in

equation (5) by the new factor (106 - 0.06 SFE)/SFE(6 - 0.06 SFE). This plan yields a 90 percent

probability of obtaining a determination of compliance when the true mean is equal to the

standard.

For enforcement testing, DOE is considering a plan similar to 2) above but changing the

probability of determination of compliance from the 10th percentile to the 2.5th percentile.

Questions and Request for Comments

(1) Please provide comments on the two sampling plans DOE is considering for compliance

testing.

(2) Please describe other approaches you believe DOE should consider.

12:00 - 1:00 Lunch (on your own)

1:00,- 1:45 Selection of a measure of energy consumption for distribution transformers.

Questions and Request for Comments

(1) Are there any strong reasons why efficiency should not be used?

(2) Should other measures of energy consumption be considered: e.g., loss power normalized

(3)

relative to output kVA, either on per unit basis or percentage basis?

Is reporting of efficiency and losses at reduced loading levels appropriate for an energy

conservation standard?

1:45 - 2:20 Burden imposed on industry, especially small manufacturers, by additional

testing and data processing

Questions and Request for Comments

(1) What specific requirements in the NIST draft test procedure are causing concern about

significant additional burden imposed by testing requirements? Please cite difficulties

anticipated.

2:20 - 2:30 Break

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2:30 - 3: 00 Selection of reference temperatures -- the reference temperatures in

consensus standards lack uniformity.

Questions and Request for Comments

Please provide comments, especially if there are in your view strong reasons for or against

the following modifications in reference temperatures from the values established in ANSI

Standards C57.12.00 and C57.12.01:

(1) Specifying reference temperature of 20°C for no-load losses of dry-type transformers (also

required by TP 1).

(2) Specifying a single reference temperature of 75°C for load losses of dry-type transformers

having all five insulation classes and two loading levels (also required by TP 1), in effect

10 temperature rise conditions are approximated by one. Calculation of the actual

temperature rises indicates that for'four conditions the reference temperature rise is

underestimated (the actual temperature will be higher than 75 °C), for five it is

overestimated, and for one the calculated temperature is 75°C.

(3) Specifying a reference temperature of 55°C for load losses of liquid-immersed

transformers at 50% load.

3:00 - 3: 30 Requirement for applying corrections to measurement data of both liquidimmersed and dry-type types of transformers.

Questions and Request for Comments

(1) Are there concerns about applying corrections, if required, to measurement data of drytype transformers as is already done for liquid immersed transformers?

3:30 - 4: 00 Requirement for quality assurance in testing.

Questions and Request for Comments

(1) Are there concerns about applying measurement accuracy requirements to dry-type

transformers, as is now done for liquid-immersed transformers, and about including a

clause for guidance from ISO 9001-1993 on measurement quality assurance procedures?

4:00 - 4:30 NEXT STEPS & CLOSING REMARKS

4:30 ADJOURNMENT

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