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Phase rotation?

Discussion in 'Question of the Day' started by derekleffew, Apr 14, 2016.

  1. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Another from the huddled masses...

    "Why is the direction of phase rotation critical when powering 3Ø chain motors?"

    Students only for one week please.
     
    Last edited: Apr 16, 2016
  2. JohnD

    JohnD Well-Known Member Fight Leukemia

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    Not an answer but a question, what do you call the 3 phases?
    A, B, C
    1, 2, 3
    X, Y, Z
    H1, H2, H3
    Curlley, Larry, Moe
    Other?
     
  3. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    Is anyone permitted to answer this or is there a one week hold for geezers on this question as well?
    Toodleoo!
    Ron Hebbard.
     
  4. JohnD

    JohnD Well-Known Member Fight Leukemia

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    Hmmmmm, good question, I guess I should have maybe posted this elsewhere.
     
  5. robartsd

    robartsd Active Member

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    I don't think I've ever called them anything. I'd likely always refer to them by however they are labeled for what I am working on. Recently the only designation I've seen is the A, B, C on my dimmer pack (connected to service with at Blue 3P+N+E IEC 60309), so I'd be most likely to refer to phases as A, B, and C. If I were working with dimmers with color coded conductor connectors, I would likely refer to phases by color (Red, Blue, and Black). As I've never used three phase motors, I haven't ever been concerned with the direction of phase rotation.
     
  6. porkchop

    porkchop Well-Known Member

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    L1, L2, L3
    U, V, W
     
  7. RickR

    RickR Well-Known Member

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    XYZ, ABC, never just 123 but both H1 H2 H3 & L1 L2 L3 as @robartsd said, depending on marking and who I'm talking to.

    I've called them Other things but always as a group and I'm sure the filters won't like those terms ;)
     
  8. JD

    JD Well-Known Member

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    I'll take any/all of the above, as long as it is consistent throughout it's usage. (As it was a second question anyway.)
    XYZ is most common on connectors.
    L1, L2, L3 most common on other hardware.
    I did see some pretty graphic-characters on a Chinese motor recently!
     
  9. petercav17

    petercav17 Active Member Fight Leukemia

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    Phase rotation determines the direction that the motor spins? Which would explain the phase reverse switch on distros?
     
  10. dramatech

    dramatech Well-Known Member

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    I traveled with an ice skating show for a few years, and the rotation direction of the 30 horse power compressors that we used was critical as compressors don't work very well when turning backwards. All of the cooling fans and liquid pumps also were in need of correct rotation. That is why there was a phase monitor on the unit, that would not allow anything to operate until the phases were connected correctly.
     
  11. Dionysus

    Dionysus Well-Known Member

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    Naming of phases as stated doesn't really matter, again I call them by what they appear as. And the name doesn't really mean anything unless everything is installed correctly.
    How many times Ive powered up a motor and had to reverse phases.

    As stated a motor will spin backwards if the phases are not in the correct order. Move ONE leg and fixed. Each phase (as its name states) is 120-degrees out of phase from the previous phase.

    However typical terms are used L1, L2, L3, where in Canada have MANDATORY colour codes L1 = Red, L2 = Black, L3 = Blue, and for ISOLATED Orange, Brown and Yellow in that order. I believe there is not a mandatory requirement in the US, just "common practice" and I believe I have seen Americans using Black, Red, Blue.... So watch out for that.
     
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  12. robartsd

    robartsd Active Member

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    I would not be surprised at all to see Black, Red, Blue. In single phase wiring I have seen, the hot is usually black with red added when there is a second hot. Anyone starting from that could naturally think of blue as the third hot when they encounter three phase.
     
  13. tjrobb

    tjrobb Active Member

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    And 480Y/277V tends to be brown orange/purple yellow; gray neutral. Purple is supposed to be used, but isn't common, so orange gets used even though it's supposed to be for B phase of high-leg 240V delta. Medium voltage is a different can of worms, but you shouldn't be messing with that anyway. [emoji6]
     
  14. epimetheus

    epimetheus Well-Known Member

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    ICEA Method 1 - E2 (K-2) for multiconductor cables requires black, red, blue, orange, yellow, brown for the first 6 conductors. Beyond that, a second color get's appended - red w/ black, blue w/ black, orange w/ black, yellow w/ black, brown w/black, for 7-11. the 12th conductor starts the next appended color - black w/ red.

    http://www.calvertwire.com/nema_k2_color_chart.php

    Based on this, I usually use (and expect to see) black, red, blue for 280Y/120V and orange, yellow, brown for 480Y/277V. Interesting that Canada requires red, black, blue as I see that sometimes with (U.S.) power company schematics (especially those from the 70's and 80's).

    Bottom line, if phase rotation is important to your equipment, make sure you have a phase rotation meter in your toolbox. (Did I tiptoe around not answering the question sufficiently?)
     
  15. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Okay, but WHY is phase rotation particularly important with chain hoists? Besides the motor running backwards.

    One cannot move ONE leg without disturbing another. "Swap any two legs" is more properer, I think.
     
  16. damjamkato

    damjamkato Member

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    Limit switches? If operating with incorrect phase rotation direction, the limit switches won't stop the motor at the ends of travel.
     
  17. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Correct, @damjamkato . Now, can you tell us how these switches work/don't work before I summon @LRonHebbard (the question suggestor)?
     
  18. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    Hmm . . . I think I've just been confused with L. Ron Hubbard of Dianetics & Scientology founding fame.
    Toodleoo!
    Ron Hebbard.
     
  19. damjamkato

    damjamkato Member

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    If I recall correctly, the gears driving the limit switch shaft are controlled by the direction of the motor. Two nuts travel on the shaft, representing the upper and lower limits. If a nut hits the end of travel, it open the circuit, stopping the motor. However, the upper limit circuit is only active when pressing up on the controller, and the down when pressing down.

    On a phase reversed motor, the "up" circuit will be active while the chain is actually traveling down. If the lower limit is reached, it will fail to stop the motor, because the upper limit switch is still closed. The same is true for the other direction of travel.

    It's been a while since my CM training, so I'm not 100% sure on the accuracy of this.
     
  20. DuckJordan

    DuckJordan Well-Known Member

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    Damjamkato I think you are correct as we've "flipped" phase to gain a few more inches of trim height using this same principle.
     

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