PTC thermistor have positive temperature coefficient resistance characteristics. When the temperature reaches its Curie point,Semiconductor ceramic phase change begins, Its resistance value increases rapidly with the temperature increases. Near the control temperature point Tk, Changes are particularly evident. When the ambient temperature is abnormally elevated, Equipped with PTC thermistor through the resistance change, Protect the circuit and turn on or off the circuit, To protect the motor.

Common methods for protection of motor overheating: Is in the motor stator winding buried in a very small volume of PTC thermistor temperature head. Under normal circumstances the motor overheat protection PTC thermistor in a low resistance state,Does not affect the normal operation of the motor. When the motor internal overheating due to failure, The thermal resistance of the PTC thermistor for the overheat protection of the motor, With the relay power loss release, The motor stops running, Wait for troubleshooting after re-running. The advantage of this protection method is to directly monitor the temperature inside the winding changes. The motor is protected before the overheat temperature breaks through the insulation level of the motor. At the same time due to the PTC thermistor recoverability, Do not have to be replaced with a new one like a temperature fuse.   Technical Guide: <What is Ceramic PTC>
Motor overheat protection PTC thermistor