1. AC contactor AC contactor is widely used as power breaking and control circuit. The main contact is used to open and close the circuit, and the auxiliary contact is used to execute the control command. Generally, the main contact only has normally open contact, while the auxiliary contact often has two pairs of normally open and normally closed contacts. Small contactors are often used as intermediate relays to cooperate with the main circuit.

2. AC contactor is mainly composed of four parts

(1) The electromagnetic system includes a suction coil, a moving iron core and a static iron core;

(2) The contact system includes three groups of main contacts and one to two groups of normally open and normally closed auxiliary contacts, which are connected with the moving iron core and linked with each other;

(3) Arc extinguishing device, AC contactor with large capacity is generally equipped with arc extinguishing device, so as to cut off the arc quickly and avoid burning the main contact;

(4) Insulation shell and accessories, various springs, transmission mechanism, short-circuit ring, terminal, etc.

3.Working principle: when the coil is electrified, the static iron core will produce electromagnetic attraction, which will pull the moving iron core in. Because the contact system is linked with the moving iron core, the moving iron core drives three moving contacts to act at the same time, the main contact is closed, the auxiliary normally closed contact mechanically connected with the main contact is opened, and the auxiliary normally open contact is closed, so as to connect the power supply. When the coil is powered off, the suction disappears, and the linkage part of the moving iron core is separated by the reaction force of the spring, so that the main contact is disconnected, the auxiliary normally closed contact mechanically connected with the main contact is closed, and the auxiliary normally open contact is disconnected, thus cutting off the power supply.