A transformer is a device consisting of two or more coils of insulated wire that transfers alternating current by electromagnetic induction from one coil to another to change the original voltage or current value. The term 'distribution transformer' means a transformer that  has an input voltage of 34.5 kilovolts or less,  an output voltage of 600 volts or less, and is rated for operation at a frequency of 60 Hertz.

A dry-type distribution transformer is a unit in which the core and coil assembly is immersed in a gaseous or dry compound insulating medium. A low-voltage dry-type distribution transformer has an input voltage of 600 volts or less and is air-cooled. A medium-voltage dry-type distribution transformer has a rated primary voltage between 601 V and 35 kV.

A liquid-immersed distribution transformer is a unit in which the core and coil assembly is immersed in an insulating liquid. A liquid-immersed unit has a capacity that ranges from 10 kVA to 2500 kVA.

Current Rulemaking Activities: DOE has initiated a new rulemaking to review and amend the energy conservation standards in effect for distribution transformers. This new rulemaking includes liquid-immersed, medium-voltage dry-type, and low-voltage dry-type distribution transformers. In this rulemaking, DOE is seeking comments on the current test procedure for distribution transformers. After reviewing comments, DOE will determine any necessary updates to the test procedure and may initiate a new test procedure rulemaking. As required by EISA 2007, DOE must complete a rulemaking to amend its test procedure for distribution transformers by December 2014.

On July 29, 2011, DOE gave notice that it intends to establish a negotiated rulemaking subcommittee under the Energy Efficiency and Renewable Energy Advisory Committee (ERAC) in accordance with the Federal Advisory Committee Act (FACA) and the Negotiated Rulemaking Act (NRA) to negotiate proposed Federal standards for the energy efficiency of liquid immersed and medium voltage dry-type distribution transformers. For details, see Energy Efficiency Standards for Distribution Transformers: Notice of Intent To Negotiate Proposed Rule, Federal Register, August 12, 2011.

Efficiency Rating: For distribution transformers, efficiency is defined as the ratio of the useful power output to the total power input.

Product Classes: The table that follows presents the ten equipment classes within the scope of the current rulemaking analysis and provides the kVA range associated with each.

Analyses: Under contract to DOE, LBNL's Energy Efficiency Standards Group (EES) conducted the following analyses to support stakeholder negotiations concerning amended energy conservation standards for distribution transformers, including:

• Life-Cycle Cost and Payback Period Analysis
• Shipments Analysis
• National Impact Analysis (National Energy Savings and Net Present Value)

Efficiency Standards History: The Energy Policy and Conservation Act (EPCA) of 1975 established an energy conservation program for major household appliances. The National Energy Conservation Policy Act of 1978 amended EPCA to add Part C of Title III, which established an energy conservation program for certain industrial equipment. The Energy Policy Act of 1992 amended EPCA to add certain commercial equipment, including distribution transformers.

The U.S. Department of Energy (DOE) published a final rule in October 2007 that established energy conservation standards for liquid-immersed and medium-voltage dry-type distribution transformers. 72 FR 58190 (October 12, 2007); see 10 CFR 431.196(b)-(c). During the course of that rulemaking, the Energy Policy Act of 2005 (EPACT 2005), Pub. L. 109-58, amended EPCA to set standards for low-voltage dry-type distribution transformers. (EPACT 2005, Section 135(c); codified at 42 U.S.C. 6295(y)) Consequently, DOE removed these transformers from the scope of that rulemaking. 72 FR at 58191 (October 12, 2007). Prior to publishing the energy conservation standard, DOE published a final rule test procedure for distribution transformers on April 27, 2006. 71 FR at 24972 (April 27, 2006); see Appendix A to Subpart K of 10 CFR 431.