The main function of molded case circuit breaker:

1. Under normal circumstances to connect and disconnect the no-load and load current in high voltage circuit; 2. In system fault, it with protection device and automatic matching device, quickly cut off the fault current, prevent the accident, so as to ensure the safe operation of the system.

In general, there is no lubrication in the case of plastic MCCB, and it is often required to lubricate its actuating mechanism. The action of the thermal relay is automatically cut off the power when the motor is overloaded, the thermal relay structure is composed of two pieces of different expansion coefficients of metal sheets, the first expansion coefficient when the current is too large, to cut off the power supply function. After the operation of the thermal relay, manual reset and automatic reset. Effect of fuse: when the fuse failure or abnormal circuit, with the current increasing, and increase the current may damage the circuit in some important devices or expensive devices, there may even cause a fire burned circuit.