The contactor is an automatic switching device used to connect or disconnect the AC and DC main circuit with load or the large-capacity control circuit. The main control object is the electric motor. In addition, it is also used for other electrical loads, such as electric heaters, electric welding machines, lighting equipment, etc.

The contactor can not only switch on and off the circuit, but also has the function of low voltage release protection. The contactor has a large control capacity and is suitable for frequent operation and remote control. It is one of the important components in the automatic control system.