1 | Building Technologies Program eere.energy.gov

The Parker Ranch installation in Hawaii

BUILDING TECHNOLOGIES PROGRAM

Distribution Transformers

Energy Conservation Program

Preliminary Analysis

James Raba

U.S. Department of Energy

Energy Efficiency & Renewable Energy

Jim.Raba@ee.doe.gov

October 12, 2011
2 | Building Technologies Program eere.energy.gov

• Transformer Loading

• Transformer Lifetime

• Transformer Peak Load Factor

• Changes to LCC Subgroups

• Equipment Price Trends

• Electricity Prices

• Limited Design Selection Due to a Fixed Efficiency

LV LCC Adjustments
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RMS Load for DL 7

0

100

200

300

400

500

600

4.2% 11.5% 18.8% 26.2% 33.5% 40.1%

Frequency

RMSLoading (annual) Forecast values

Trials 10,000

Mean 22.1%

Median 22.2%

Mode 27.6%

Standard Deviation 6.6%

Variance 0.4%

Skewness -0.0845

Kurtosis 2.65

Coeff. of Variability 0.2959

Minimum 2.8%

Maximum 41.9%

Range Width 39.1%

Mean Std. Error 0.1%
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Service Lifetime

Average transformer lifetime is 32 years

Reference: ORNL-6847 Determination Analysis of Energy 

Conservation Standards for Distribution Transformers

Each transformer in the LCC simulation has a unique lifetime

Failure rates:

0.5% per year from the first year of installation, due to lightning and 

other random causes

Additional 0.5% per year due to corrosion, starting in year 15

The failure rates are used to create a survival function, 

assuming a standard Weibull shape
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Lifetime: DL 7

0

100

200

300

400

500

600

700

2 13 25 37 49 59

Frequency

life Forecast values

Trials 10,000

Mean 32

Median 33

Mode 35

Standard Deviation 12

Variance 138

Skewness -0.3293

Kurtosis 2.78

Coeff. of Variability 0.3686

Minimum 1

Maximum 60

Range Width 59

Mean Std. Error 0
6 | Building Technologies Program eere.energy.gov

• Transformer peak load is a flat distribution ranging from 70 to 

90% of nameplate

Peak Load Factor
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• Would like to the explore the possibility of adding Datacenters 

as a subgroup to the LCC analysis

– Would need data on:

• Any material limitations

• Any manufacturing techniques limitations

• Load Factor

• Average lifetime

• To implement this subgroup we would need data.

• Can we use the same price, efficiency data that is currently 

used for DL8?

Possible LCC Subgroup: 

Datacenters
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• Estimates the impacts of increasing or decreasing transformer 

prices at a national level over time.

• These are calculated as sensitivities in the NIA

– The default case assumes flat prices over time

– The low price case is modeled on historical price index from 

1967 to 2010.

– The high price case is modeled on the historical price index from 

1991 to 2010.

Equipment Price Trends
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Equipment Price Trends (cont.)

0.600

0.700

0.800

0.900

1.000

1.100

1.200

1.300

1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

Price Factor Index (2010=1)

Year

Low Price Scenario: PPI Exponential Fit (1967 to 2010) Default Scenario: Constant Price Index

High Price Scenario: PPI Exponential Fit (1991 to 2010) Deflated PPI (2010=1)
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• Electricity prices were re-scaled using AEO Price Trends

Electricity Prices

80%

85%

90%

95%

100%

105%

2005 2010 2015 2020 2025 2030 2035

Real Price Relative to 2008

Year

Reference Case High Growth Low Growth
11 | Building Technologies Program eere.energy.gov

• Fixed efficiency ratings only impact the selection of 

transformers with a diversity of A and B in the most extreme 

cases.

• Here A and B are calculated from customer marginal price for 

energy

• The following slides illustrate the designs selected in the LCC 

for DL7.

Limited Design Selection Due to a 

Fixed Efficiency
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DL 7: EL 1

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0 50 100 150 200 250 300 350 400 450 500

Load Losses (watts)

No Load Losses (watts)

Design Load Losses (LL) vs No-Load Losses (NL)

at rated load

Available Designs

Selected Designs, Base

Selected Designs, Standard
13 | Building Technologies Program eere.energy.gov

DL 7: EL 3

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0 50 100 150 200 250 300 350 400 450 500

Load Losses (watts)

No Load Losses (watts)

Design Load Losses (LL) vs No-Load Losses (NL)

at rated load

Available Designs

Selected Designs, Base

Selected Designs, Standard
14 | Building Technologies Program eere.energy.gov

DL 7: EL 7

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0 50 100 150 200 250 300 350 400 450 500

Load Losses (watts)

No Load Losses (watts)

Design Load Losses (LL) vs No-Load Losses (NL)

at rated load

Available Designs

Selected Designs, Base

Selected Designs, Standard
15 | Building Technologies Program eere.energy.gov

Thank you