scope:

This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of three-phase, 60 Hz, mineral-oil-immersed, self-cooled, pad-mounted, compartmental-type distribution transformers. These transformers are rated 2500 kVA and smaller, with high-voltages of 34 500 GrdY/ 19 920 volts and below, and with low-voltages of 480 volts and below. These transformers are generally used for step-down purposes from an underground primary cable supply. This standard covers the connector, bushing and terminal arrangements for radial or loop feed systems. Either certain minimum dimensions (see Figures 1, 2, 3, 7, 8, and 11) or certain specific dimensions (see Figures 4, 5, 6, 9, 10, and 12) shall be specified. This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer.

NOTE-Refer to latest USA federal regulations concerning PCB contamination in transformers.¹

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

Purpose

This standard is intended for use as a basis for determining performance, interchangeability, and safety of the equipment covered, and to assist in the proper selection of such equipment.