Superseded by IEEE Std C57.12.44-2005. The performance, electrical and mechanical interchangeability, and the safety of the equipment are covered. The proper selection of such equipment is established as a basis for use in this standard. Certain electrical, dimensional, and mechanical characteristics are described; and certain safety features of three-phase, 60 Hz, low-voltage (600 V and below) network protectors are taken into consideration. This equipment is used for automatically connecting and disconnecting a network transformer from a secondary spot or grid network.

This standard establishes the electrical, mechanical, and dimensional characteristics of three-phase, 60 Hz, low voltage (600v and below) network protectors. It covers performance, interchangeability, and safety of this equipment which is used to automatically conenct and disconnect network transformers from secondary spot and grid networks.

There were many comments that were received on the affirmative ballots that have suggested possible improvements to the standard. Also, the specialized network protector fuses and their relationship, compatibility, and electrical and mechanical interchangeability in the various protectors needs expanding. These will provide the basis for the required 1999 revision of this standard.