Modular contactor has the same function as the traditional contactor. It opens or closes the circuit of the main contact part through the control coil, and transmits the use status signal of the load through the auxiliary contact. But, it different as the traditional contactor, it has a smaller Modular unit (9mm/unit), 1P is 18mm, 2P is 36mm, 3P is 54mm, 4P is 72mm, the current range from 1A to 100A, it can be used with other modular size guide rail protection devices, the use of space is more flexible and suitable for a variety of scenarios.