scope:

This voluntary consensus 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:

a) Instrument transformers

b) Step voltage and induction voltage regulators

c) Arc-furnace transformers

d) Rectifier transformers

e) Specialty transformers

f) Grounding transformers

g) Mobile transformers

h) Mine transformers

Mandatory requirements

When this standard is used on a mandatory basis, the words shall and must indicate mandatory requirements, and the words should and may refer to matters that are recommended and permitted, respectively, but not mandatory.

NOTE-The introduction of this standard describes the circumstances under which the document may be used on a mandatory basis.¹

¹ Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement the standard.