In modern power systems, various asynchronous and synchronous motors occupy a major portion of the low voltage grid load. During the operation of the motor, due to the mechanical failure of the motor itself, such as bearing overheating, fan damage, etc., or other electromagnetic faults such as phase failure, short circuit, undervoltage operation, etc., the motor will operate abnormally, causing adverse consequences. Therefore, it is extremely important to choose a circuit breaker that matches the AC motor protection circuit of the circuit breaker.
Based on the requirements of the AC motor protection of the circuit breaker, when selecting the type, in the selection, the CM3E type circuit breaker with adjustable short-circuit protection setting value should be selected, which can realize fine stepless adjustment and expand the setting current coverage.
Since the phase failure of the circuit breaker AC motor is usually caused by the disconnection of the external power line and the disconnection of the internal stator winding, it is quite fatal to the motor. Once the phase is broken, the remaining two phases of current increase rapidly, and the motor will be in a section. After the time is burned, it should be protected by a circuit breaker with phase failure and unbalance protection. In the selection, a full range of CM3Z series motor protection circuit breaker AC motor with phase failure and zero protection can be selected.