ANSI C57.12.21-1992 PDF

Scope: This standard is intended for use as a basis for determining performance, interchangeability, and safety ofthe equipment covered, and to assist in the proper selection of such equipment.This standard covers certain electrical, dimensional, and mechanical characteristics and takesinto consideration certain safety features of single-phase, 60 Hz, mineral-oil-immersed, self-cooled, padmounted,compartmental-type distribution transformers with high-voltage bushings. These transformersare rated 167 kVA and smaller, with high-voltages of 34500 GRD/19900 volts and below for operationbetween one phase and grounded neutral, and low-voltage of 240/120 volts. These transformers aregenerally used for step-down purposes from an underground primary cable supply.NOTE—Refer to latest federal regulations concerning polychlorinated biphenyl (PCB) contaminations in transformers.This standard covers bushing and terminal arrangements for both radial and loop feed systems.This standard does not cover the electrical and mechanical requirements of any accessorydevices that may be supplied with the transformer.

ANSI C57.12.21-1992 Referenced Document

ANSI C57.12.70-1978 Terminal Markings and Connections for Distribution and Power Transformers

1992 ANSI C57.12.21-1992 American National Standard Requirements for Pad-Mounted, Compartmental - Type Self - Cooled, Single - Phase Distribution Transformers With High Voltage Bushings; High-Voltage, 34500 GRYD/19920 Volts and Below; Low - Voltage, 240/120 Volts; 167 kVA and Sma