The working principle of AC contactor

The AC contactor is based on the electromagnetic principle, which is utilized to drive the contact through the control circuit and the movable armature for managing the on-off operation of the main circuit. The mechanism behind its operation is that, when the AC contactor coil receives electrical power, it creates an electromagnetic attraction in the static iron core, which in turn draws the moving iron core to operate the main contact for closing. In addition, the auxiliary contacts of the AC contactor get switched from normally open to normally closed, and from normally closed to normally open. After the AC contactor coil loses power, the electromagnetic force created by the static iron core vanishes, leading to the resettlement of the movable iron core via the spring reaction force. Subsequently, all contacts reset back to the starting state.