Automatic monitoring system for electro-mechanical relays - uses two independent sets of relay contacts operated by common mechanism with two mutually inverse contacts

摘要

The system is intended to safeguard against welding of the relay contacts or blockage or breakage of the mechanism. Two sets of contacts (3,4) are mechanically independent but are actuated by the same command or recall operation. A series electrical connection is made between a contact of the first set and an inverse contact of the second set, allowing an external connection to readily detect a contact failure through the series path established if a failure occurs. The series path can be used to provide a trigger for a crow bar protection scheme, initiating operation of the back up protection system. An alarm may be provided in the form of an indicator light or a buzzer. The device may be radio-controlled.