GT200-C series fan special protector and AC contactor form a motor protection control circuit. Mainly used for AC 50Hz/60Hz, rated voltage 400V~690V, rated current to 200A-600A and above, using the secondary side sampling current method of transformation ratio transformer to three-phase induced draft fans, centrifuges, punches, rotating machines in cement plants, etc. The asynchronous motor is protected against failures such as open phase, overload, blocked rotor, blockage, and three-phase unbalance that may occur when the asynchronous motor is in a heavy-load starting state for a long time.