New IEEE Standard - Superseded. This standard sets forth the requirements for power transformer application. This standard is intended to be used as a basis for performance, interchangeability, and safety of the equipment covered and to assist in the proper selection of such equipment. This document is a product standard that covers certain electrical, dimensional, and mechanical characteristics of 50 Hz and 60 Hz, liquid-immersed power transformers and autotransformers. Such power transformers may be remotely or integrally associated with either primary switchgear or substations, or both, for step-down or step-up purposes and base rated as follows: 833 kVA and above single-phase, 750 kVA and above three-phase. This standard applies to all liquid-immersed power transformers and autotransformers that do not belong to the following types of apparatus: instrument transformers, step voltage and induction voltage regulators, arc-furnace transformers, rectifier transformers, specialty transformers, grounding transformers, mobile transformers, and mine transformers.