Auxiliary relay with four changeover contacts, aimed to supervise the failure of trip supply.

Connecting the relay across the trip circuit supply, the equipment is normally energized. Faults will occur when the trip voltage is lost, so the relay drops off in those cases, providing the related signs and alarms. In order to avoid faulty alarms due to instantaneous supply voltage dips, the drop off time of the relay is delayed over 100 ms so those non-permanent failures of trip supply would not be considered.

Auxiliary supply circuit supervision relays can be manufactured with different LED indicator configuration