Basic question, 3 phase terminology...

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dbuckley said:
Absolutely, everywhere in the world.

Note that machine manufacturers will (in my experience anyway) ensure that all motors in the machine are wired with the same phase sequence order, so if one motor is correct, then all will be.
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We are in agreement. Except.... where you wrote

"will ensure that all motors in the machine are wired with the same phase sequence order"

I would write:

"will ensure that all motors in the machine are wired to have the proper rotation"

The reason I say this is that, even if builder of the machine is using two of the exact same motors on the machine, one of them may need to go one way, one may need to go the other. So the phase sequence connection may be different for each motor.

This is probably semantics and we are saying the same thing.

Edit to add: What I am saying is that when installing a multi-motor manufactured machine, either every motor will run the right direction, or every motor will run backwards. The manufacturer during testing is most likely going to either test the machine to ensure proper rotation, or they will have already done prototyping with the same motors to know how they need to be wired for proper rotation throughout the machine.
 
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crossman said:
Well, there really is no "standard" color code. Houston ordinance is using Brown-Purple-Yellow-Gray for 480Y/277. Lots of places use Brown-Orange-Yellow-Gray for the same system. And you will find plenty of installations where the 480 is black-red-blue.


Or r,s,t, whatever. OK Houston is almost as weird as Austin in a redneck kind of way. Your right about lack of standards. I guess that is why I always use black tape to phase black conductors. Yeah, I remember the pneumonic BOY for "high voltage"480Y/277. Or purple, never had a problem either way in Houston though some insist orange is for high leg only. But south of Round Rock, "if you go to the honkeytonk you'd better "Bring(brown) Your(yellow) P(purple)"" Local pneumonic...

Here is an excerpt from the POCO's website:



That would have to be for an installation in which the customer equipment can provide more power than the customer is using, and the customer's equipment sends the excess back into the utility.

Not necessarily, could be a ups

Lacking further info, that statment from the poco makes no sense whatsoever. Unless I have missed some IEEE standards or such, where does it say that ABC is CW? NESC? PoCo standards?

AE does not say clockwise, they say C-B-A, and if they find the install otherwise, they label the meter C-A-B.

Again, what makes "C" phase from a generator "C" phase? Is there some characteristic of the "C" winding that makes it distinguishable from "A"? Or is it totally dependent on the person making the connections?
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Sorry i have not learned how to parse the text in order to rebut a post
 
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RE: UPS

I am assuming that a UPS is going to sense the incoming service rotation and match itself to that all by itself. The same thing would hold true of a PV inverter connected to a utility.

Although I have serviced a large UPS system, I did not do the install, so I don't know what pains where taken to ensure proper phase arrangements and rotation. Still, I am going to bet that a UPS is going to sync itself to the utility regardless of our connection. I could be wrong.

Anyone? Is it necessary when installing a UPS to determine the service rotation and match it?

RE: CBA vs CAB

I can't speak for the Austin Linemen, but I bet the actual xfmr secondaries connected to whatever phase arbitrarily done. Now, possibly they take the pain to check the rotation and label it on the meter by some pre-planned system of CBA or CAB. Sounds like they are going to some unnecesaary trouble.
 
crossman said:
RE: UPS

I am assuming that a UPS is going to sense the incoming service rotation and match itself to that all by itself. The same thing would hold true of a PV inverter connected to a utility.

Although I have serviced a large UPS system, I did not do the install, so I don't know what pains where taken to ensure proper phase arrangements and rotation. Still, I am going to bet that a UPS is going to sync itself to the utility regardless of our connection. I could be wrong.

Anyone? Is it necessary when installing a UPS to determine the service rotation and match it?

RE: CBA vs CAB

I can't speak for the Austin Linemen, but I bet the actual xfmr secondaries connected to whatever phase arbitrarily done. Now, possibly they take the pain to check the rotation and label it on the meter by some pre-planned system of CBA or CAB. Sounds like they are going to some unnecesaary trouble.
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I'll check with an Austin Lineman for his arbitrariness. Your probably right that the XFMR is arbitrarily connected. Some metering is installed downstream from the customer installed service distribution enclosure and an EC may have reversed the rotation, not the utility.

An Eaton tech told me their UPS gear was phase rotation sensitive but he could have been selling me a line
 
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here is the meat of my thoughts:

If we fed a building with a delta to wye utility xfmr with 480Y/277 secondary, and in the service raceway we had 3 black conductors and a white conductor for the neutral, and the linemen connected these wires to their service drop, is there any test you could perform in the building to determine which wire was "A" phase, which was "B" phase, etc?

And, are there any safety concerns about terminating any particular "black" conductor in any particular service equipment ungrounded conductor lug?
 
crossman said:
Anyone? Is it necessary when installing a UPS to determine the service rotation and match it?
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When wiring a UPS, then installer will generally use the colour sequence local to the facility, so in old school UK, the phase colours are red - yellow - blue, and so they'll always be connected in that order, unless there is some markings to the contrary. We've already discussed how the rotation direction (ie the absolute phase sequence) varies from service to service, so the order doesn't actually mean anything, only that the phase order is consistent within a facility.

The UPS will phase align itself to the incoming supply, so the output looks the same as the input. It has to do this so that when the thing switches into static bypass the load doesn't experience reversing of phase rotation.

What is really really important is when you have an external manual bypass make before break arrangement on the UPS that the phase sequence is the same for the UPS output terminals and the manual bypass, otherwise there is going to be fireworks, as the phases are bolt shorted to each other...

And Crossman - yes, we are violently agreeing :)
 
Different countries use use different symbology for identifying electrical phases. Below is the symbol equivalency.

Phase A = L1 = R = U
Phase B = L2 = S = V
Phase C = L3 = T = W

Ray
 
rotation

rotation

In my limited experience no matter which way you hook it up you will have to change it. If it's supposed to be clockwise it's running counter, if it's supposed to be counter it's clockwise.

Seriously:grin:
 
crossman said:
That is downright mean-spirited!
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Yep, but ain't it fun?
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SparkyJ said:
In my limited experience no matter which way you hook it up you will have to change it. If it's supposed to be clockwise it's running counter, if it's supposed to be counter it's clockwise.

Seriously:grin:
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The same thing happens when we're looking for an address, and hit the street in the middle. If we go left, it'll be to the right, and vice versa.
 
I believe that the correct terminology for rotation is "the order in which the phases reach their positive maximum". Which is how the vertices of the phasor follow each other when rotated counterclockwise.

Not to be confused with arrangement of conductors on a transmission or distribution line, since these can change due to transposition; and there is no standard for this.

A-B-C is very common however phases can be rolled, and the utility may use C-A-B (and is very common). If connected to a utility transformer that means Distribution conductor C to H1, A to H2, and B to H3. To the electrician it really doesn't matter, they will connect service as L1 to X1, L2 to X2, and L3 to X3 and designate the panel as A, B, C; and as long as the service is never interconnected to another part of the system, it doesn't really matter. But it's also why that when you think you have the phases correct, they have to be swapped due to motor rotation.

However, at the substation and power plant level, it is very important that phases are not rolled or rolled properly, because it would make interconnection with other substations and utilities, or plants impossible. Hence why us engineers create phasor 3-line drawings which indicate what phase is connected to what bus/line, and it is imperative that phase angles be kept track of.
 
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