Dc coil contactor is mainly used for long distance switching on and off dc circuit， and frequently start, stop, reverse and reverse brake dc motor, also used for frequently connecting and disconnecting lifting electromagnet, solenoid valve, clutch electromagnetic coil and so on. Dc coil contactor has two kinds of structures: three-dimensional arrangement and plane arrangement. Some products are derived from ac contactor. Therefore, the structure and working principle of dc coil contactor are basically the same as that of ac contactor, mainly composed of electromagnetic mechanism, contact system and arc extinguishing device.
Dc coil contactor, the main circuit of the current is dc, generally used less, mainly used in precision machine tool dc motor control.
Ac contactor, the current of the main circuit is ac, widely used, most of the electricity is ac.
2.The electromagnetic mechanism of dc coil contactor has no eddy current and hysteresis loss, and the core is composed of a whole piece of soft steel. Short circuit ring is not required assembled on the end face.
3.Dc coil contactor is connected with alternating current to generate eddy current and hysteresis loss. The core is heated and the coil is burnt out. Ac contactor into direct current, impedance sharply reduced, current increased, coil burnt out.
Different applications, the choice of ac or dc depends on the coil, dc coil contactor coil can only through dc, ac contactor coil can only through ac to work. Generally speaking, in the ac loop, the main loop use ac, and the auxiliary loop generally takes electricity from the main loop as the control loop, so the control loop is obviously ac, so the ac contactor should be used. If for some application, like an ac power failure, the equipment needs to continue to work when the power is switched on, you need to separate the power circuit from the control circuit. Main circuit with ac, auxiliary control circuit with dc, this can be achieved, because the power failure when the dc does not stop, because dc is generally from the battery, can supply a few hours. In this way, after the power failure, the equipment stops running, but because of the existence of direct current, so the contactor depends on the connection, such as the power, the equipment will continue to operate.