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Thread: 9 lead motor

  1. #1
    Join Date
    Aug 2005
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    21

    9 lead motor

    was informed that a contractor (electrical) wired a motor, customer called us (hvac dept) and stated his motor is not running, only humming.
    upon trouble shootin found that the motor was wired wrong, 208/230 3 phase line voltage. motor was found to be wired for 460 volts high voltage.
    I know that on a 9 lead motor high voltage is in series & low voltage is in parallel. my question is what exactly made the motor fail?
    Is it the higher current with the lower voltage wired in series?

    thanks Jesaire

  2. #2
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    without knowing anything more than you told us...did it really fail or was it just stalled? if it actually failed, my guess is that the motor did not have enough torque to properly spin the rotor. without enough "spin" the motor did not cool itself and it ended up being an electric heater. if it was just stalled, you (he) effectively had a 40 hp nameplate motor and turned it into a 20 hp motor, for example. after awhile, i would imagine that it would fail due to overheating.

    good luck.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  3. #3
    Join Date
    Nov 2004
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    North Florida/South Georgia
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    Quote Originally Posted by jayguy View Post
    without knowing anything more than you told us...did it really fail or was it just stalled? if it actually failed, my guess is that the motor did not have enough torque to properly spin the rotor. without enough "spin" the motor did not cool itself and it ended up being an electric heater. if it was just stalled, you (he) effectively had a 40 hp nameplate motor and turned it into a 20 hp motor, for example. after awhile, i would imagine that it would fail due to overheating.

    good luck.
    Well said
    All my leon freaked out!

  4. #4
    Join Date
    Oct 2001
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    6,966

    Hmm

    did you rewire it for 208/230 to see if it bummed and or ran,was it open windings or grounded out to the frame?how long was it miswired and ran?
    "when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY

  5. #5
    Join Date
    May 2004
    Location
    Caldwell, ID
    Posts
    395
    I had a customer once who replaced a pump motor. They call me to say it was running slow, and there was a brown stripe around the motor.

    The ranch foreman (this was when I was in the ag business) saw 9 leads in the motor, 3 leads from the line, so he just picked the first 3 from the motor and let her rip. He wire nutted the rest together.

    I can't believe it even ran for a second and didn't blow a breaker! When I got there it was done.

    I agree with JayGuy

  6. #6
    Join Date
    Oct 2006
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    Central Texas
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    633
    Jayguy hit the nail on the head. Too much resistance in the windings, can not pull enough amps to turn the motor over. How hot was that motor? It could still be ok. cool it off wait awhile ohm the windings make sure all three ohms readings are the same. Hope this helps.
    Sic Semper Tyrannis.

  7. #7
    Join Date
    Dec 2006
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    Middle Tennessee
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    even this guy could of wired that motor properly
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  8. #8
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    Jun 2001
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    Louisville, KY
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    Quote Originally Posted by Airmechanical View Post
    even this guy could of wired that motor properly
    You might be amazed at the number of calls I get about low voltage/high voltage on the motor label.
    Perhaps you should have read the instructions before calling.

  9. #9
    Join Date
    Dec 2006
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    Middle Tennessee
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    *

    Quote Originally Posted by jrbenny View Post
    You might be amazed at the number of calls I get about low voltage/high voltage on the motor label.
    i know, but it just kills me how someone can turn something simple into rocket science!



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