A circuit breaker refers to a switching device that can close, carry and break current under normal circuit conditions, and can close, carry and break current under abnormal circuit conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. Circuit breakers can be used to distribute electric energy, start asynchronous motors infrequently, and protect power lines and motors. When they have serious overload or short-circuit and under-voltage faults, they can automatically cut off the circuit. Its function is equivalent to a fuse switch. Combination with overheating and underheating relay, etc. Moreover, it is generally not necessary to change the components after breaking the fault current. At present, it has been widely used. Power distribution is an extremely important link in the generation, transmission and use of electricity. The power distribution system includes transformers and various high and low-voltage electrical equipment, and the low voltage circuit breaker is a widely used electrical appliance.