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Summary

Energy Efficient Commercial and Industrial Transformers

Improved efficiency distribution transformers are available for use in the industrial and commercial sectors. Existing efficiency standards cover three-phase low and medium voltage liquid and dry-type transformers.

Synopsis:

Most of the electricity used in commercial and industrial facilities flows through distribution transformers on the customer side of the meter. Commercial buildings often have one or more low voltage distribution transformers on each floor to supply power for plug loads, lighting, HVAC, and other building systems.  These distribution transformers are energized 24 hours per day, 365 days per year.  Improved efficiency (Tier 1) transformers are now available from many manufacturers.

Transformer efficiency has been improved through changes in design, core or winding material selection, and in the type and amount of insulation used in the transformer. Higher grade steel in the core and more copper in the windings improve efficiency. Amorphous metal reduces core losses when compared with silicon steel. Multiple core designs have evolved that allow for powering down unneeded sections of the transformer core.  The Consortium for Energy Efficiency (CEE) identified two efficiency tiers:  Tier 1 yields a 35% reduction in total losses (fixed losses plus variable losses)  while Tier 2 results in a roughly 50% reduction in losses compared to federal minimum standard level as the baseline.

Even small incremental improvements in transformer efficiency result in significant energy savings.  CEE calculated the energy savings of Tier 1 and 2 transformers relative to baseline transformers. Savings range from 414 kWh/year for a 15 kVA Tier 1 transformer to over 21,100 kWh/year for a 1000 kVA Tier 2 unit.   Getting these new improved efficiency transformers into service is difficult as transformers have an average useful life of 30 years.  

Energy Savings: 35%
Energy Savings Rating: Comprehensive Analysis  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.

Status:

Details

Energy Efficient Commercial and Industrial Transformers

Improved efficiency distribution transformers are available for use in the industrial and commercial sectors. Existing efficiency standards cover three-phase low and medium voltage liquid and dry-type transformers.
Item ID: 612
Sector: Commercial, Industrial
Energy System: Power Systems--Transformers

Synopsis:

Most of the electricity used in commercial and industrial facilities flows through distribution transformers on the customer side of the meter. Commercial buildings often have one or more low voltage distribution transformers on each floor to supply power for plug loads, lighting, HVAC, and other building systems.  These distribution transformers are energized 24 hours per day, 365 days per year.  Improved efficiency (Tier 1) transformers are now available from many manufacturers.

Transformer efficiency has been improved through changes in design, core or winding material selection, and in the type and amount of insulation used in the transformer. Higher grade steel in the core and more copper in the windings improve efficiency. Amorphous metal reduces core losses when compared with silicon steel. Multiple core designs have evolved that allow for powering down unneeded sections of the transformer core.  The Consortium for Energy Efficiency (CEE) identified two efficiency tiers:  Tier 1 yields a 35% reduction in total losses (fixed losses plus variable losses)  while Tier 2 results in a roughly 50% reduction in losses compared to federal minimum standard level as the baseline.

Even small incremental improvements in transformer efficiency result in significant energy savings.  CEE calculated the energy savings of Tier 1 and 2 transformers relative to baseline transformers. Savings range from 414 kWh/year for a 15 kVA Tier 1 transformer to over 21,100 kWh/year for a 1000 kVA Tier 2 unit.   Getting these new improved efficiency transformers into service is difficult as transformers have an average useful life of 30 years.  

Baseline Example:

Baseline Description: 1500 kVA Three-Phase Medium Voltage Dry-Type Transformer
Baseline Energy Use: 51198 kWh per year per unit

Comments:

The energy use is for a 1500 kVA medium voltage dry-type transformer serving a load of 500 kW.  The old base case transformer has an efficiency of 98.8% at its 50% load point.  The baseline "energy use" is expressed in terms of annual energy losses.  (Note: the loss term can be expressed as 31.1 kWh/kVA). 

Manufacturer's Energy Savings Claims: Currently no data available.
Best Estimate of Energy Savings:

"Typical" Savings: 35%
Low and High Energy Savings: 35% to 36%
Energy Savings Reliability: 5 - Comprehensive Analysis

Comments:

To determine energy savings, we must know the efficiency of old, standard efficiency transformers as well as the performance of state-of-the art units. The efficiency values at 50% of rated load are given in Table #1 for old standard efficiency transformers, for NEMA Class 1 transformers (as defined in NEMA Standard TP-1 of 1996), and for transformers that meet the DOE’s new Energy Conservation Standards for Distribution Transformers.  DOE’s minimum efficiency standards Final Rulemaking was issued on April 18th, 2013 and applies to all three-phase, medium-voltage dry type distribution transformers manufactured for sale or imported into the U.S. after January 1st, 2016.

Table #1 Transformer Efficiency over Time (medium voltage, dry-type)

kVA Rating         Base Case Transformer          DOE EPCA Transformer Efficiency
   150                                97.9                                           98.6

   500                                98.4                                           98.96

  1500                               98.8                                           99.22

Assuming that a 1500 kVA transformer is serving a 500 kW load, the old base case transformer has an efficiency of 98.8% with losses equivalent to 51,198 kWh/year.  The new DOE EPCA compliant transformer has full load efficiency of 99.22% and reduces losses to 34,433 kWh/year, a reduction of 35.3%. 

Energy Use of Emerging Technology:
33,278.7 kWh per unit per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: unit
Currently no data available.
First Cost: Currently no data available.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Reference and Citations:

Rank & Scores

Energy Efficient Commercial and Industrial Transformers

There is no TAG available for this technology.
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