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How does the PTC thermistor action for motor overheat protection?

2014-06-05

For motor overheating protection commonly used method is embedding volume of tiny PTC thermistor with Temperature Sensor head in the motor stator winding ,the motor overheating protection PTC thermistor is in low resistance state under normal circumstances,which does not affect the normal operation of the motor.

When there's overheating inside the motor caused by malfunction,resistance of the overheating protection PTC thermistor inside the motor jumps,the matched relay loses electric release,the motor stops working accordingly,and will start working again after troubleshooting.

The advantage of this kind of protection method is to monitor the temperature inside the winding directly,which can protect the motor before the overheating temperature breakthrough the motor insulation class.At the same time, due to the recoverability of PTC thermistor,don't like thermal fuse that must need be replaced.

PTC is a kind of thermal resistor that resistance with temperature rise and rise,and with temperature decreasing and drop.There's normal rated current for each specifications of the PTC.PTC thermistor is in series with one root electric load line,when the current exceeds the normal rated current of the PTC thermistor,PTC internal temperature rises when the current rising and resistance of the thermal resistor is rising at the same time.Temperature rise to a certain limit resistance close to up to shut the circuit.Restores conduction in the oposite condition.

The motor thermal protection PTC Thermistor is equivalent to thermal resistor,which will power off automatically when the temperature of the motor exceeds its rated temperature in use.So as to protect the motor will not be burnt out due to overheating.

when temperature of the motor to reduce, the PTC thermal resistor will be connected to the power supply automatically.