Relays are the logic elements of a protection system which sense the fault and cause the circuit-breaker trip circuits to be energized and the breakers to open their contacts.
继电器是保护系统的逻辑元件，它感知故障，并使断路器解扣电路带电和断路器打开触点。
2
Before starting any work, check the de-energized parts for presence of power and ground or short-circuit them in addition to insulating adjacent live parts and elements.