The magnetic starter is a combination of a three-pole AC contactor, a thermal relay for overload protection, and a control button. The magnetic starter is an electric appliance specially designed to remotely control the starting, stopping, and reversing of the motor. When the voltage is too low protection or overload, it can automatically trip, but it can not play the role of short circuit protection. In actual engineering, the magnetic starter must be used in series with the fuse, and the short circuit fault is cut off by the fuse.