The working principle of the contactor is: when the contactor coil is energised, the coil current will generate a magnetic field, the resulting magnetic field causes the static iron core to generate electromagnetic suction to attract the moving iron core, and drives the action of the AC contactor point, the normally closed contact is disconnected, the normally open contact is closed, and the two are linked. When the coil is de-energized, the electromagnetic attraction force disappears, and the armature is released under the action of the release spring, causing the contacts to return to their original state. The normally open contacts open, and the normally closed contacts close. The working principle of a DC contactor is somewhat similar to that of a temperature switch.