This circuit breaker has the advantages of advanced structure, reliable functions, high breaking capacity, elegant appearance and small volume. Its frame and components are made of high fire-retardant and shockproof plastic. It is used in the circuit of AC 50Hz/60Hz, rated voltage below 400V. It is used for the overload protection, short circuit protection in the office, residence, building, etc. It can also be used for an infrequent switchover of the circuit under normal conditions.