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Thread: you're wrong. no you're stupid. well you're stupider so there.

  1. #41
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    Quote Originally Posted by Sahib View Post
    One sue sign the transformer is not big enough is it won't allow the motor to run by dropping out contactors due to excessive voltage drop on starting. But OP has not reported any such happening. So reductio ad absurdum, the transformer is big enough.
    An 875kVA transformer isn't big enough for a 1,000 hp motor. If you were in the business of designing drive systems you would have no difficulty in understanding that.
    There is no ad absurdum about it.
    Si hoc legere scis nimium eruditionis habes.

  2. #42
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    Quote Originally Posted by Besoeker View Post
    An 875kVA transformer isn't big enough for a 1,000 hp motor. If you were in the business of designing drive systems you would have no difficulty in understanding that.
    There is no ad absurdum about it.
    let's agree to disagree
    imho it is sufficient
    especially if the 840 was measured at the drive output, then motor load is only ~750 kva (90 kva for the filter/xfmr consumption) on a 875 kva xfmr
    need more info from the op



  3. #43
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    Quote Originally Posted by Ingenieur View Post
    let's agree to disagree
    imho it is sufficient
    If it was, it wouldn't run over temp.
    Si hoc legere scis nimium eruditionis habes.

  4. #44
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    Quote Originally Posted by ggunn View Post
    What is reality?
    A concept
    Sometimes I don't know whether I'm the boxer or the bag.

  5. #45
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    Quote Originally Posted by Besoeker View Post
    If it was, it wouldn't run over temp.
    it did not run over temp
    he said that is what he expected to see ('usually') but did not, but rather the output was clamped at 840 which surprised him (and imo impossible)
    that is why we need more info
    but on the surface, if measured at the drive out, the most convenient point, the xfmr only operated at 750 or 85%



  6. #46
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    Quote Originally Posted by Besoeker View Post
    An 875kVA transformer isn't big enough for a 1,000 hp motor.
    Wouldn't it depend on how much the motor was loaded? Perhaps the motor was oversized, or the calculated size was just over the next size down?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  7. #47
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    [QUOTE=Ingenieur;1872442]it did not run over temp]/QUOTE]
    I don't see how else you can interpret "usually it just runs over temp."
    Seems unambiguous to me.
    Si hoc legere scis nimium eruditionis habes.

  8. #48
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    Quote Originally Posted by electrofelon View Post
    Wouldn't it depend on how much the motor was loaded? Perhaps the motor was oversized, or the calculated size was just over the next size down?
    Quite right. Possibly a number of things. But if the transformer got too hot that's one problem right there.
    Si hoc legere scis nimium eruditionis habes.

  9. #49
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    These things here got me confused. Why do other people here claim that the setup is okay when the OP mentioned "it failed"? Did I miss a lot?

  10. #50
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    Quote Originally Posted by Besoeker View Post
    An 875kVA transformer isn't big enough for a 1,000 hp motor. If you were in the business of designing drive systems you would have no difficulty in understanding that.
    There is no ad absurdum about it.
    1HP = 746 watts.
    1,000 HP = 746,000 watts.

    that's not allowing for any losses whatsoever.
    no heat, transformer loss, zip.

    125% would be 932,500 watts.
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