# Phase rotation?



## derekleffew (Apr 14, 2016)

Another from the huddled masses...

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

Students only for one week please.


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## JohnD (Apr 15, 2016)

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?


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## RonHebbard (Apr 15, 2016)

JohnD said:


> Not an answer but a question, what do you call the 3 phases?
> A, B, C
> 1, 2, 3
> X, Y, Z
> ...


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


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## JohnD (Apr 15, 2016)

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


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## robartsd (Apr 15, 2016)

JohnD said:


> Not an answer but a question, what do you call the 3 phases?
> A, B, C
> 1, 2, 3
> X, Y, Z
> ...


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.


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## porkchop (Apr 15, 2016)

JohnD said:


> Not an answer but a question, what do you call the 3 phases?
> A, B, C
> 1, 2, 3
> X, Y, Z
> ...



L1, L2, L3
U, V, W


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## RickR (Apr 15, 2016)

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


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## JD (Apr 15, 2016)

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!


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## petercav17 (Apr 16, 2016)

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


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## dramatech (Apr 18, 2016)

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.


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## Dionysus (Apr 18, 2016)

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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## robartsd (Apr 18, 2016)

Dionysus said:


> I believe I have seen Americans using Black, Red, Blue.... So watch out for that.


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.


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## tjrobb (Apr 18, 2016)

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]


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## epimetheus (Apr 19, 2016)

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?)


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## derekleffew (Apr 19, 2016)

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


Dionysus said:


> As stated a motor will spin backwards if the phases are not in the correct order. Move ONE leg and fixed.


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


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## damjamkato (Apr 19, 2016)

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


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## derekleffew (Apr 19, 2016)

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


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## RonHebbard (Apr 19, 2016)

derekleffew said:


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


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


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## damjamkato (Apr 19, 2016)

derekleffew said:


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


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.


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## DuckJordan (May 1, 2016)

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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