IEEE C37.90:1989 (R1994)

Revision Standard - Superseded.
Superseded by IEEE Std C37.90-2005. This standard applies to relay systems that protect and control apparatus that generate, and distribute and use electric power. This standard defines service conditions and specifies relay performance requirements and performance information that relay manufacturers shall provide.

This standard applies only to relays and relay systems used to protect and control power apparatus. 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 the control of power apparatus.
The purpose of this standard is to specify standard service conditions, standard ratings, performance requirements, and requirements for testing of relays and relay systems associated with power apparatus.