IEEE C37.90:2005 (R2011)

Revision Standard - Inactive-Reserved.
Service conditions, electrical ratings, thermal ratings, and testing requirements are defined for relays and relay systems used to protect and control power apparatus. This standard establishes a common reproducible basis for designing and evaluating relays and relay systems.

This standard specifies standard service conditions, standard ratings, performance requirements, and testing requirements for relays and relay systems used to protect and control power apparatus. A relay system may include computer interface equipment and/or communications interface equipment, such as a carrier transmitter/receiver or audio tone equipment. It does not cover relays designed primarily for industrial control, for switching communication or other low-level signals, or any other equipment not intended for control of power apparatus.
The purpose of this standard is to establish a common reproducible basis for designing and evaluating relays and relay systems.