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Thread: Delta vs Wye motor connections

  1. #11
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    Quote Originally Posted by mivey
    Carl, your picture looks like the 1/2 voltage version of crossman's picture. ...
    Yes,as you saw, they are the same. Just grab the corners and stretch it out to the HV version.

    carl
    Using the code for a design guide is a sign of incompetance

  2. #12
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    I will add a link to the motor connection diagram as well http://www.electricmotorwarehouse.co...n_diagrams.htm

    this will be pretty instering combation you may run into one of the days

    Merci,Marc
    Marc
    master electrician
    Wisconsin and Paris France

    "Pas de problème, il marche n'est-ce pas?" (No problem, it works doesn't it?)

  3. #13
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    Quote Originally Posted by Jraef
    Assuming you are in North America, don't get hung up on the "Delta vs Wye" winding issue, it is almost completely irrelevant. A NEMA designed motor is what it is, you usually have no way of knowing, short of dissection, whether it is wound in Delta or Wye internally, nor should you care. .
    Looking through some datasheets here at the plant I noticed that we have both 480V 3-wire delta and 480V 3-wire wye motors. Our system voltage is 480V. Basically what you are saying is as long as the motor is rated for 480V we should not care weather we install a delta or wye motor on our system? If we installed a 3-wire wye motor on our 480V system would the motor only see 277V and thus only give 1/3hp as you explained?

    Quote Originally Posted by Jraef
    How that relates to "Leads" in single speed NEMA motors is as follows:
    "6 lead motors" are either single voltage motors, Wye or Delta wound (you won't know the difference) or they are single voltage, Wye-Dela start. They can also be dual-windings, for instance as you would use with a Part Winding starter. In some RARE instances they are dual voltage motors, but the voltage ratio is always 1.732:1, so that would be 480/277V or 575/331V; you won't see a lot of those, not worth considering.
    So if I have a 6-lead 480V motor that I want to put on my system I have an option of how I connect this motor either wye or delta? What do you mean when you say "you wont know the difference" regarding the wye or delta windings? With 6 leads, dont you have the option of wiring a motor for wye or delta? On my 480V system I'm guessing I want to wire this motor for delta? What would happen if i wired it in the wye configuration, would I only have 277V on the motor and thus only 1/3hp? Would I want to use the wye configuration if I only had a 277V system voltage?

  4. #14
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    Quote Originally Posted by mull982
    Our system voltage is 480V. Basically what you are saying is as long as the motor is rated for 480V we should not care weather we install a delta or wye motor on our system? If we installed a 3-wire wye motor on our 480V system would the motor only see 277V and thus only give 1/3hp as you explained?
    If the motor is designed for 480 volts and the windings connected correctly, it will give the full rated horsepower. You are correct that in a wye motor each internal coil (or set of two coils in series for a dual volatage motor) will only have 277 volts across it, however that is what it is designed to run on. Each coil or set of coils in a delta wound motor is designed for 480 volts.
    So if I have a 6-lead 480V motor that I want to put on my system I have an option of how I connect this motor either wye or delta?
    That motor would be designded for wye start and delta run. You don't really have a choice.[/quote]
    On my 480V system I'm guessing I want to wire this motor for delta? What would happen if i wired it in the wye configuration, would I only have 277V on the motor and thus only 1/3hp? Would I want to use the wye configuration if I only had a 277V system voltage?
    I am not aware of any 3 phase 277 volt systems so you have to supply it with 480 and connect it for delta.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  5. #15
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    Quote Originally Posted by crossman
    The high voltage connection is straight-forward. The low voltage connection isn't quite so obvious.

    It would be if you look at it like this: Mentally "pick up" the three L's (the little "open Deltas") above, and move them towards the center of the triangle, so the pairs of coils overlap, literally placing them in parallel. You'd have T6 and T7 meeting at T1, T9 and T5 meeting at T3, and T4 and T8 meeting at T2.

    Looking at one side of the large triangle, say T1 to T4 and T7 to T2, each pair of windings can be in series or in parallel; in series for high volts, or in parallel for low volts. Either way, each winding receives its design voltage, thus current, thus power, thus its contribution to output horsepower.

    Similar to dual-voltage transformer windings, like buck-boosts.


    Added: Carl's drawing shows the 'after' positions of what I described above: http://forums.mikeholt.com/attachmen...5&d=1208219067
    Last edited by LarryFine; 04-15-08 at 11:14 AM.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  6. #16
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    Obvious:

    Obviously, you can wire the split windings in series or in parallel. Same flux, same coil currents, twice the line current at half the voltage.
    Don't mess with B+!
    (Signal Corps. Motto)

  7. #17
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    When I said "the low voltage connection isn't quite so obvious" I wasn't implying that I didn't know how to do it. I was just saying "it isn't quite so obvious as the high voltage connection."

    One way to look at the low voltage connection is that we are creating three open deltas.... not that we actually are, but going from my diagram, the LV connection would appear to be three open deltas.

  8. #18
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    Quote Originally Posted by mull982
    So if I have a 6-lead 480V motor that I want to put on my system I have an option of how I connect this motor either wye or delta?
    No, if you have a 6-lead 480v motor, you have the option of 240v or 480v, but it will remain wye or delta. A 9-lead motor is actually a 12-lead motor with one connection point inaccessible.

    To switch a motor between wye and delta, you need all of the winding ends individually accessible, which means it will be a 6-lead, single-voltage motor, or a 12-lead, dual-voltage motor.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #19
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    Quote Originally Posted by LarryFine
    No, if you have a 6-lead 480v motor, you have the option of 240v or 480v
    I am missing something here. Can a six lead 480v motor also be connected for 240 volts?

  10. #20
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    Connections

    here is a bunch of motor connection dwgs i ran across awhile back

    http://www.usmotors.com/Connections/Connections.htm

    enjoy
    Why is it, when it comes to the NEC, the obvious is never simple and the simple is never obvious?

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