Contactors are divided into AC contactors (voltage AC) and DC contactors (voltage DC), which are used in power, distribution and electric field. Generally speaking, contactor refers to the electrical apparatus which controls the load by using the magnetic field generated by the current flowing through the coil to close the contact.

The working principle of the contactor is: when the contactor coil is electrified, the coil current will produce a magnetic field, the magnetic field will make the static iron core produce electromagnetic attraction, attract the moving iron core, and drive the AC contactor point action, the normally closed contact will open, the normally open contact will close, the two are linked. When the coil is powered off, the electromagnetic force disappears, the armature is released under the action of the release spring, so that the contact is restored, the normally open contact is opened, and the normally closed contact is closed. The working principle of DC contactor is similar to that of temperature switch.