Electromagnetic contactor (contactor) refers to an electrical appliance that uses the current flowing through the coil to generate a magnetic field in industrial electricity to close the contact so as to control the load. The contactor is composed of electromagnetic system (armature, stator core, electromagnetic coil), contact system (normally open contact and normally closed contact) and arc extinguishing device. Structural composition Electromagnetic contactor is mainly composed of transmission device (electromagnetic mechanism), contact device (actuator) and arc extinguishing device. 1. Electromagnetic mechanism The electromagnetic mechanism includes three parts: moving core (armature), static core and electromagnetic coil. The electromagnetic coil is connected with current to generate electromagnetic suction and drive the contact to act. Electromagnetic mechanism is one of the important parts of electromagnetic contactor. The electromagnetic mechanism is composed of coil, iron core (static iron core), armature (moving iron core), pole shoe, iron yoke and air gap. The coil and iron core in the electromagnetic mechanism do not move in the working state; The armature is movable. The electromagnetic mechanism converts the electromagnetic energy generated by the electromagnetic coil into mechanical energy through the action state and action process of the armature and the corresponding mechanical mechanism to drive the contact to close or open, so as to realize the control purpose of the controlled circuit.