IEEE C57.12.38-2009

This standard covers certain electrical, dimensional, mechanical characteristics and safety requirements of singlephase, 60 Hz, liquid-filled, self-cooled, pad-mounted, compartmental-type distribution transformers. These transformers are rated 167 kVA and smaller, with the high voltages of 34 500 GrdY/19 920 V and below for operation between one phase and grounded neutral, and low voltage of 240/120 V. 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. This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer. This standard is intended to define the electrical, mechanical, dimensional, performance, and interchangeability requirements of the transformers covered under this standard and to assist in the proper selection of such equipment. These requirements will provide a more standard transformer design, which will benefit manufacturers by reducing the number of designs. Users will be provided a document, which can be used to purchase a transformer of standard design, without having to develop any additional standards. This will be helpful to less experienced users. It also will promote standardization of these types of transformers. This standard will replace ANSI C57.12.21-1992 [B1] and ANSI C57.12.25-1990 [B2]. New IEEE Standard - Superseded. This standard covers certain electrical, dimensional, mechanical characteristics and safety requirements of single-phase, 60 Hz, liquid-filled, self-cooled, padmounted, compartmental-type distribution transformers. These transformers are rated 167 kVA and smaller, with the high voltages of 34 500 GrdY/19 920 V and below for operation between one phase and grounded neutral, and low voltage of 240/120 V. 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. This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer.