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Thread: VFD Ground fault

  1. #11
    Join Date
    Jun 2003
    Location
    NE (9.1 miles @5.07 Degrees from Winged Horses)
    Posts
    9,699
    We were happy for about a week in this ongoing saga. Going on the assumption that the present motor has not failed. (Not even sure of that now. Actual Motor rewind shop called with indication that it was most likely high voltage spikes on non inverter duty wiring. Typical VFD damage. Motor ran for a couple years before we got load reactor on it. Long story.)

    First, this is an AB 753. I found out last week the demise of the previous drive was Dust, Dirt and General Crud. Would have been nice to know sooner, although I did make the suggestion years ago to cover this drive in the off season.

    Obviously the factory inlet filter is a waste of time for this installation. We trimmed and rolled a section of fiberglass filter to fit behind the factory one, but how do I know what is to much? Guessing if I still get dirt in the cabinet it's not enough.

    We will probably be making another trip up there because they will be putting the rebuilt original motor back on tomorrow, and do the Autotune, etc.

    Next question, seeing as this is an intermittent problem at the moment is there any cleaning that I could do in the field that may correct a DD&GC problem?
    Tom
    TBLO

  2. #12
    Join Date
    Sep 2008
    Location
    UK
    Posts
    11,563
    Quote Originally Posted by ptonsparky View Post
    We were happy for about a week in this ongoing saga. Going on the assumption that the present motor has not failed. (Not even sure of that now. Actual Motor rewind shop called with indication that it was most likely high voltage spikes on non inverter duty wiring. Typical VFD damage. Motor ran for a couple years before we got load reactor on it. Long story.)
    It is usually high rate of change of voltage (dv/dt) rather than high voltage spikes that do older motors in.
    Si hoc legere scis nimium eruditionis habes.

  3. #13
    Join Date
    Jun 2003
    Location
    NE (9.1 miles @5.07 Degrees from Winged Horses)
    Posts
    9,699
    Quote Originally Posted by Besoeker View Post
    It is usually high rate of change of voltage (dv/dt) rather than high voltage spikes that do older motors in.
    My phrasing was is wrong again. Thank you.
    Tom
    TBLO

  4. #14
    Join Date
    Sep 2008
    Location
    UK
    Posts
    11,563
    Quote Originally Posted by ptonsparky View Post
    My phrasing was is wrong again. Thank you.
    Just my experience. We had one project where the motors were random wound rather than mesh wound. And failed after a few weeks. The motor manufacturer took the pain. As one guy commented at the time you would not normally expect 780 kW motors to be disposable items.
    Si hoc legere scis nimium eruditionis habes.

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