In electrotechnics, because can quickly cut off the ac and dc main circuit and can frequently connected with large current control circuit of the device (800 a), so often used in motor as control object, also can be used as a control plant equipment, electric heater, machine tools and all kinds of power units and so on electric power load, contactor can not only connect and cut off the circuit, but also has a low voltage protection. Contactor control of large capacity, suitable for frequent operation and remote control, is one of the important components of automatic control system.

In the industrial electrical, contactor type many, working current in the range of 5 a - 1000 - a, its widespread use.