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Thread: Two speed one winding motor troubleshooting advice

  1. #121
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    Quote Originally Posted by Besoeker View Post
    They receive just V. The PF and I is what the motor makes of it.
    a motor will not run without i
    The difference between genius and stupidity is that genius has its limits.

  2. #122
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    Quote Originally Posted by Ingenieur View Post
    a motor will not run without i
    Correct.
    The motor consumes I. It is not forced upon it as I'm sure you know.
    Si hoc legere scis nimium eruditionis habes.

  3. #123
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    Quote Originally Posted by Besoeker View Post
    Correct.
    The motor consumes I. It is not forced upon it as I'm sure you know.

    it consumes power, actually converts
    the i that enters = the i that leaves, kcl, which means no i is 'consumed'
    as you know
    The difference between genius and stupidity is that genius has its limits.

  4. #124
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    So let me ask this, because I’m not sure how to measure it and what the consequences would be. Maybe you guys do?

    In high speed we are bringing back the T1, T2, and T3 connections, with #2 wire that has read too hot on IR scans dating back to 2002, and shorting these three wires together. Now at the starter end how do we measure what the voltage drop on these #2 conductors are? If it is found to be excessive what symptoms will be displayed? If allowed to go on long enough what harm may happen?

    Seems to me best we can do is compare currents. T1 and T6 should have the same current, correct? The degree of imbalance would only be attributable to difference in winding and/wiring impedance, correct? Trying to wrap my head around if both currents should sum to zero even.

  5. #125
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    shop vs field
    same motor
    ~same v, >460 rating
    same load, ~0%
    as some say pf has no bearing
    no apparent damage as lo speed is fine, and i is balanced at 0% and 115%
    we do not know operating temps, but unlikely to increase i by 30%

    so what could possibly account for the delta?
    no seems willing to venture a guess
    The difference between genius and stupidity is that genius has its limits.

  6. #126
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    Quote Originally Posted by Russs57 View Post
    So let me ask this, because I’m not sure how to measure it and what the consequences would be. Maybe you guys do?

    In high speed we are bringing back the T1, T2, and T3 connections, with #2 wire that has read too hot on IR scans dating back to 2002, and shorting these three wires together. Now at the starter end how do we measure what the voltage drop on these #2 conductors are? If it is found to be excessive what symptoms will be displayed? If allowed to go on long enough what harm may happen?

    Seems to me best we can do is compare currents. T1 and T6 should have the same current, correct? The degree of imbalance would only be attributable to difference in winding and/wiring impedance, correct? Trying to wrap my head around if both currents should sum to zero even.
    each wye must sum to 0
    the wyes are not common/bonded to each other
    one is permanent made at the motor
    the other via the #2 by contactors 110' away
    this may lead to a few % i imbalance per coil pair
    I wonder of connecting the 2 wye centers would matter?
    doubt it, better balance, but it's not bad as is

    I calc'ed the #2 drop, less than 5 v plus another 2 from the 500's
    less than 2% and about 470 at the motor
    he measured 274 but this does not factor in the #2 drop

    his wye i at contactor is ~158 avg (via the #2)
    his fla is 327 avg
    if perfect balance ~163
    his are 158 and (327-158) = 169
    158/327 = >48%, the other <52%, does not seem like an issue
    the contactor wye has the 110' of #2 so you would expect it to be a bit lower

    imo no wiring issues
    the motor was checked
    what does that leave?
    The difference between genius and stupidity is that genius has its limits.

  7. #127
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    Quote Originally Posted by Besoeker View Post
    They receive just V. The PF and I is what the motor makes of it.
    Quite true. Not sure what was up with the shop vs site pf stuff. Kinda weird but maybe I missed his point.
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  8. #128
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    Quote Originally Posted by phineascage View Post
    Thank you Sir. I believe it's going to be sent out again anyway whether we really want to or not as it's getting hot enough to cook eggs on. It's also producing that old familiar burnt winding smell.
    Have you considered some aux cooling to get you by until it can be taken out of service? Additional cooling can forgive a multitude of sins...for a little while anyway.
    BB+/BB=?

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