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  • Revision:1990 Edition, 1990
  • Published Date:January 1990
  • Status:Active, Most Current
  • Document Language:English
  • Published By:Institute of Electrical and Electronics Engineers (IEEE)
  • Page Count:19
  • ANSI Approved:Yes
  • DoD Adopted:No

  • Foreward

    Accredited Standards Committee on Transformers, Regulators, and Reactors, C57, has for many years been developing and correlating standards on transformers and regulators. The data used in this work have been gathered from many sources, including the standards of the Institute of Electrical and Electronics Engineers and the National Electrical Manufacturers Association, reports of committees of the Edison Electric Institute, and others.

    This standard was prepared by the Subcommittee on Distribution Transformers, Overhead and Pad-Mounted, C57.12.2.

    Suggestions for improvement of this standard will be welcome. They should be sent to the National Electrical Manufacturers Association, 2101 L Street, NW, Washington, DC 20037.


    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.

    This standard covers certain electrical, dimensional, and mechanical characteristics, and takes into consideration certain safety features of single-phase, 60-Hz, mineral-oil-immersed, self-cooled, pad-mounted, compartmental-type distribution transformers with separable insulated high-voltage connectors. These transformers are rated 167 kVA and smaller, with high voltages of 34500 GrdY/19 920 volts and below for operation between one phase and grounded neutral, and low voltages of 240/120 volts. These transformers are generally used for step-down purposes from an underground primary cable supply.

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

    This standard covers two connector and terminal arrangements for loop feed systems. Either Type 1 (see Figure 1) or Type 2 (see Figure 2) arrangements shall be specified.

    This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer.