Anonymous asked in Science & MathematicsEngineering · 10 years ago

thermal and ground protection of a motor?

dear all..

i have a question wanna to ask..i know that PTC thermistor are use for motor protection against thermal, short-circut, overcurrent..etc..but how does a PTC thermistor are mounted or installed in the motor?..and one more..some installation are using ground check diode for earth fault protection..but how does it work?..also if u all can..provide me with some technical notes or references to help my understanding in this matter..

thank u..

2 Answers

  • 10 years ago
    Favorite Answer

    RE: PTC:

    Stands for Positive Temperature Coefficient

    As its temp increases, the resistance goes up. It is put in close contact with the windings so it is warmed by excessive winding temperature. In addition, it is in series with the moror. If the current goes high, it is also heated and increases resistance. The increased resistance limits the motor current untl it all cools.

    The Diode thing, I don't know.

  • Anonymous
    10 years ago

    Hey mate

    The thermistors are most usually mounted in the stator windings. There is usually the a thermistor for each phase and sometimes thermistors on the motor bearings.

    As for the check diode i am unsure.

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