Integral testing of relays and circuit breakers

Among all equipment types considered for seismic qualification, relays have been most extensively studied through testing due to a wide variation of their designs and seismic capacities. A temporary electrical discontinuity or ``chatter`` is the common concern for relays. A chatter duration of 2 milliseconds is typically used as an acceptance criterion to determine the seismic capability of a relay. Many electrical devices, on the other hand, receiving input signals from relays can safely tolerate a chatter level much greater than 2 ms. In Phase I of a test program, Brookhaven National Laboratory performed testing of many relay models using the 2-ms chatter criterion. In Phase II of the program, the factors influencing the relay chatter criterion, and impacts of relay chatter on medium and low voltage circuit breakers and lockout relays were investigated. This paper briefly describes the Phase II tests and presents the important observations.