The working principle of AC contactor is to use electromagnetic force and spring force to achieve the connection and disconnection of contacts. AC contactor has two working states: power loss state (release state) and power on state (action state). When the attraction coil is energized, the static iron core generates electromagnetic attraction, the armature is closed, and the connecting rod connected with the armature drives the contact to act, so that the normally closed contact disconnector is energized; When the suction coil is powered off, the electromagnetic attraction disappears, the armature is reopened, making the normally open contact closed, releasing under the action of the position spring, and all the contacts are reset accordingly, making the contactor in the power loss state.