New IEEE Standard - Superseded. This IEEE Standards product is part of the C57 family on Power Distribution and Regulating Transformers. Electrical, mechanical, and safety requirements are set forth for step-voltage and induction-voltage regulators, single-phase and three-phase, oil-filled and dry-type, not exceeding 2500 kVA of regulation for three-phase units, or not exceeding 833 kVA of regulation for single-phase units. These provide a basis for the establishment of performance, limited electrical and mechanical interchangeability, and safety requirements of equipment described and for assistance in the proper selection of such equipment.