QCX5 air compressor protector (Magnetic starter for Air compressor) is made up of AC contactor and thermal over-load relay that are installed inside of one dustproof metal enclosure, easy to operate by one left button. The thermal over-load relay has the function of temperature compensation, automatic and manual reset, and then the current can be set by pulling the adjusting knob. The thermal over-load relay also has one phase-failure protection mechanism and it can cut off the power-supply of the motor to protect when the motor is running with phase-failure.-----Tianhui Electricmagnetic starter