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Distribution Transformer MV Subcommittee

Negotiation Meeting #2

Wednesday, 12 October 2011
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Agenda

• Requested Data

• Requested Changes to Analysis

• Open Questions

• Next Steps
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Agenda

• Requested Data

• Requested Changes to Analysis

• Open Questions

• Next Steps
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• Core Weight vs. Efficiency

• Total Weight vs. Efficiency

• Bidirectional Exchange of Engineering Data

• Steel Price Sensitivity Tool

• Simplified Cost / Efficiency Charts

Requested Data
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Agenda

• Requested Data

• Requested Changes to Analysis

• Open Questions

• Next Steps
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• TSL Corresponding to Competitive Steels

• Materials Price Updates / Scenarios

• Scaling

– End-of-Range

– Phase Harmonization

• Liquid-Immersed Standards by BIL

• Standard for Pad-mounts, Pole-mounts, Network/Vault, and 

Substation

• Size and Weight Constraints

Requested Changes to Analysis
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1. Achieve comfort with existing representative units.

2. Extrapolate the efficiency levels of representative units to 

higher and lower kVAs.

3. New Equipment Classes – BIL, Substation, Network, Pad, 

Pole

1. Differential Consumer Utility

2. Differential Ability to Meet an Efficiency

Analysis Priorities
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• Proposal to use template created for bidirectional data 

exchange

• Controlled comparison address engineering data

– Selling Price by Efficiency less useful

– Materials Prices held constant or close

Existing Representative Units
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• Historically, losses scaled using the “.75 rule”, where the ratio 

of the losses of two transformers is set equal to the ratio of 

their kVA ratings raised to the .75 power

• Several manufacturers have given feedback that this is a 

good practice, but that the proper exponent can deviate from 

.75 depending on transformer type

• Concern that accuracy can decline near extremes of kVA

range

Scaling
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• Proposal

– Conduct limited analysis at extremes of kVA range to 

determine appropriate scaling exponent

• Benefits

– Allows slope to assume a value other than .75

– Allows ends of scaling range to be treated accurately

– Allows extension of results for one type of transformer 

to a different, but similar type (e.g., medium BIL case 

to high and low cases)

Scaling
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• DOE understands that BIL strongly affects efficiency in 

medium-voltage dry-type transformers and created high, 

medium, and low BIL standards in the 2007 rulemaking.

• BIL less of a factor in liquid-immersed units, but perhaps 

still significant if standards rise further.

– Feedback that current representative units produce too low a 

standard at lower BILs and too stringent a standard at high BILs.

• Proposal

– Scale BIL standards from reference BIL

Potential New Equipment Classes
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• Several have commented that certain types of liquidimmersed transformers could have different utilities and 

abilities to meet certain efficiencies

– Pad-mounted, pole-mounted, substation, network/vault

• Interested in hearing more about the reasons for doing that 

and how it might be executed

• Sensible to hold equivalent different types of transformers 

with identical As and Bs?

Potential New Equipment Classes
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Scaling
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Scaling
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Scaling
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Scaling
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Scaling

• Committee needs to determine if that methodology is 

sensible and applicable

– Useful for liquid-immersed BIL scaling?

– Useful for creating other new liquid-immersed equipment 

classes?

• DOE would require corroborating engineering data on 

transformers designed to certain As and Bs to find 

appropriate logarithmic offset

• Equipment classes need rigorous definitions. What 

makes a pad? Pole? Substation?
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• At the first meeting (15-16 September), negotiators discussed a 

standard that allowed grain-oriented and amorphous transformers to 

compete.

• Met with AK, Allegheny, Metglas for input

• Agreed on selling price as a metric for equivalence

• Concern over accurate relative materials pricing

• Operating Hypothesis: if two similar transformers vary significantly in 

price, one does not get purchased

Steel Competitiveness
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Steel Competitiveness – DL5
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Steel Competitiveness – DL5
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Steel Competitiveness – DL5
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Steel Competitiveness – DL5

M3
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Steel Competitiveness – DL5

M3

ZDMH
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Steel Competitiveness – DL5

M3

ZDMH

SA1
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Steel Competitiveness – DL5

M3

ZDMH

SA1
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Steel Competitiveness – DL5

M3

ZDMH

SA1
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Steel Competitiveness – DL5

M3

ZDMH

SA1
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Steel Competitiveness – DL5

M3

ZDMH

SA1
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• Sensitive to material prices

• Weight had been proposed as a metric for competitiveness to 

reduce price sensitivity

• Weight does not drive purchasing decisions, within a range

• Weight requires an implicit assumption about relative pricing, does 

not address problem

• Plan: seek input from committee on materials prices, along with best 

guess high and low cases for the foreseeable future

Steel Competitiveness Conclusions
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Agenda

• Requested Data

• Requested Changes to Analysis

• Open Questions

• Next Steps
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• CSL and EL Selection

• Compliance of Actively Cooled Transformers

• Compliance of Transformers with Multiple BIL Ratings

• Compliance of Transformers with Multiple Primary and 

Secondary Windings

Open Questions
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Agenda

• Requested Data

• Requested Changes to Analysis

• Open Questions

• Next Steps
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Next Steps

• DOE

– make the proposed changes?

• Negotiators

– provide feedback on those changes?

• Others?

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Backup Slides

Backup Slides
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Scaling - Backup

(1) y = ax^k is equal to

(2) ln(y) = ln(a)+k*ln(x)

Let ln(y) = y’, ln(x) = x’, ln(a) = a’

(3) y’ = kx+a’ which is

(4) y = mx+b

where slope m is exponent k

and offset b is log of coefficient a
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Scaling - Backup
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Scaling - Backup

.75 slope
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Scaling - Backup
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Scaling - Backup
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Scaling - Backup
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Scaling - Backup
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Scaling - Backup
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Scaling - Backup