We know that circuit breakers can be used to distribute electrical energy, infrequently start asynchronous motors, protect power lines and motors, etc., and automatically cut off the circuit when they are seriously overloaded or short-circuited and under-voltage faults, whose function is equivalent to the combination of fuse-type switches and over-under thermal relays, etc. This is attributed to the circuit breaker lockout, to achieve the lockout function of the circuit breaker accessories include: handle latching devices, mechanical interlocking devices, and electrical interlocking devices.