When a relay disables itself, it prevents an undesired trip of the circuit breaker when the protection is no longer reliable. The system must run on backup protection until the failed relay is replaced or repaired. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers. While this is bad, It's not a. The protection relay tripping circuit refers to the critical electrical control loop that executes trip/close commands from protective relays to circuit breakers, ensuring rapid fault isolation in power systems. Essential. If a device is tripped for a permanent, serious fault (transformer differential), you want to isolate (trip) all sources and block closing / reclosing until further investigation is performed. The. During any stage of evolution of a power system, there will be some combination of operating conditions, faults or other disturbances which may cause the loss of synchronism between areas within the power system or between interconnected systems. If such loss of syn-chronism can or does occur, it. A protective relay is an intelligent electrical device designed to detect faults in power systems and initiate corrective actions such as tripping a circuit breaker. The relays share a common user interface, as shown in Figure 1, and can be customized via the programmable liquid crystal display (LCD) screen, pushbuttons.