Distribution Transformers

As defined in the Code of Federal Regulations (CFR), “distribution transformer” means a transformer that (1) has an input voltage of 34.5 kV or less; (2) has an output voltage of 600 V or less; (3) is rated for operation at a frequency of 60 Hz; and (4) has a capacity of 10 kVA to 2500 kVA for liquid-immersed units and 15 kVA to 2500 kVA for dry-type units. The term “distribution transformer” does not include a transformer that is an: autotransformer; drive (isolation) transformer; grounding transformer; machine-tool (control) transformer; nonventilated transformer; rectifier transformer; regulating transformer; sealed transformer; special-impedance transformer; testing transformer; transformer with tap range of 20 percent or more; uninterruptible power supply transformer; or welding transformer.10 CFR 431.192

Manufacturers have been required to comply with the U.S. Department of Energy (DOE) energy conservation standards for distribution transformers since 2007.