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Thread: Wiring a 230 volt motor to a 240 volt Delta 3 phase system.

  1. #1
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    Wiring a 230 volt motor to a 240 volt Delta 3 phase system.

    Is it ok to connect a 3ph 25 HP motor to delta 240 v system ?
    My only concern is that I have 256v from A to B phase, and 235 volts from B to C phase, and 246 volts from A to C Phase.
    This is from the power companies transformer. I just don't want to blow out a motor down the road.
    I thank you for your imput.

  2. #2
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    I would not be concerned about those voltages for that motor. I would be more concerned about the size of the service. That motor will be drawing about 70A. What is it for?

  3. #3
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    A 230V motor is intended to be connected to a 240V service.

    However in addition to the loading that Chris mentions, I would be concerned about the imbalance in the supply voltages. If they were all balanced 250V, that would be in the normal tolerance for a 240V service. But the level of imbalance that you mention could be a problem.

    -Jon

  4. #4
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    Quote Originally Posted by Jim33063 View Post
    Is it ok to connect a 3ph 25 HP motor to delta 240 v system ?
    My only concern is that I have 256v from A to B phase, and 235 volts from B to C phase, and 246 volts from A to C Phase.
    This is from the power companies transformer. I just don't want to blow out a motor down the road.
    I thank you for your imput.
    Is 230Vac common in the US?
    Is it a 60Hz motor?

  5. #5
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    Quote Originally Posted by Besoeker View Post
    Is 230Vac common in the US?
    Not as a supply system but as a motor rating yes.

    Quote Originally Posted by winnie View Post
    A 230V motor is intended to be connected to a 240V service.

    However in addition to the loading that Chris mentions, I would be concerned about the imbalance in the supply voltages. If they were all balanced 250V, that would be in the normal tolerance for a 240V service. But the level of imbalance that you mention could be a problem.

    -Jon
    The voltage imbalance would lead me to believe that the supply is near capacity, hence my question about the service capacity. Need to see the ungrounded voltage readings to ground here. The OP may indicate that A to ground may be high.

  6. #6
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    Quote Originally Posted by chris kennedy View Post
    Not as a supply system but as a motor rating yes.



    The voltage imbalance would lead me to believe that the supply is near capacity, hence my question about the service capacity. Need to see the ungrounded voltage readings to ground here. The OP may indicate that A to ground may be high.
    The sevice size is 100 amps . A phase to ground is 122.5v (B) phase to ground is 213v. (C) phase to ground is 122.5v .

  7. #7
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    Sounds to me like a very heavily loaded 'open delta'.

    Do you know what other loads are sharing the same supply transformers?

    -Jon

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