Dc contactor is basically the same as ac contactor in structure and working principle. It is also composed of electromagnetic mechanism, contact system and arc extinguishing device. However, the core is through direct current, no eddy current and hysteresis loss, so no heat. The coil is usually made into a long and thin cylindrical shape, which is in direct contact with the iron core and easy to dissipate heat. Dc contactor is more difficult to extinguish the arc, the general use of a strong ability to extinguish the arc magnetic blowing device.
Contactor graphics and text symbols are shown in the figure
The text and graphic symbols of a contactor
(a) Auxiliary action break contact
(b) Auxiliary moving contact
(c) main contact