The AC contactor has the advantages of small size, light weight, long life, low power consumption, and can be combined and derived as required. It can be equipped with building block auxiliary contact groups, air delay heads, mechanical interlocking mechanisms and other accessories to form a delay contactor, Star-delta starter, and can be directly plugged into and installed with thermal overload relay to form an electromagnetic starter. The product can be installed with screws, and can also be installed with 35mm (75mm) standard rails.