The motor protection type circuit breaker is one of the protection devices for the squirrel-cage asynchronous motor to be started, operated and indispensable. For motor protection, the rated current is 630A or less (that is, the protected motor is 315kW and below). It is used to start the motor infrequently and during operation. When the motor is short-circuited or under-voltage, it can be protected ( Automatically cut off the circuit).

Common motor protection type of circuit breaker

According to the use situation, there are three types of circuit breakers used as motor protection:

(1) The AC contactor is used for the starting and running of the motor, and the thermal relay is used for the overload protection, and the circuit breaker is protected. Since the contactor is used to divide and close the circuit, it can be operated relatively frequently;

(2) Using the contactor as the starting and stopping of the motor, the fault of the motor such as overload, short circuit and under voltage is broken;

(3) The starting and running of the motor and the overload, short circuit and under voltage are all operated by a circuit breaker and the energy is frequently used.