Low torque when hot

This topic contains 8 replies, has 2 voices, and was last updated by  Kurt Olson 3 months, 2 weeks ago.

  • Author
    Posts
  • #9927

    Kurt Olson
    Participant

    Hi I didnt know where to put this question but its aquestion so put in here.
    Why does my motor run hot and then the output current goes up to limit and then machine slows down?


  • #9928
    John C
    John C
    Galco Representative

    Hello Kurt, thanks for asking Galco today.

    Sounds like a serious problem but I have to ask first if you have an AC or DC motor driving the machine?


  • #9929

    Kurt Olson
    Participant

    Its a 15HP DC motor


  • #9930
    John C
    John C
    Galco Representative

    AH a DC motor, does the drive have a field controller in it or just a simple rectifier type supply?


  • #9931

    Kurt Olson
    Participant

    Whats a field controller?


  • #9932
    John C
    John C
    Galco Representative

    Ok maybe a better question would be, what is the drive you are using?


  • #9933

    Kurt Olson
    Participant

    Ok John I got the model number right here, it is a Bardac SLE24/58 drive


  • #9934
    John C
    John C
    Galco Representative

    Ok those drives usually come with a fixed field supply built in, so as the motor heats up your field current slowly goes down loosing torque so the drive has to put out more Armature power to do the same work.
    Does the motor have a cooling fan on it?
    If it does make sure it is running, and if it is a Squirrel Cage (sometimes called centrifugal) type make sure it is spinning the right direction. That type of blower blows air in the same direction if it runs backwards or forwards, big difference in air flow though if backwards.


  • #9935

    Kurt Olson
    Participant

    Yah actually it is funny you mention that cuz 1 of our old employee’s (Freddy, retired now) showed up a little while ago and said the same thing. Turns out it is running the right way but the inlet filter is so bad with dust it wasnt doing much. good call John


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