This standard specifies the minimum allowable values of energy efficiency, target minimum allowable values of energy efficiency, evaluating values of energy conservation, energy efficiency grade and test methods of power transformer.
This standard is applicable to the three-phase oil-immersed power transformers of 50Hz in rated frequency, 35kV ~220kV in voltage grade and 3150kV?A and more in rated capacity.
This standard is not applicable to the dry-type transformer, high impedance transformer and gas-filled type transformer.