Is there a "standard" labeling for phases in medium voltage metering?

[SSLA]

Folks:

We have just installed metering on a 46kV class subtransmission line with vertical configuration. We assumed the phase layout was A-B-C top to bottom but it turned out to be B-C-A. There is no neutral so we used two element metering, connecting the VT primaries B-C and A-C making the common point of connection between the voltage transformers the middle (C) phase. We put the CTs in the top and bottom phases (B and A). So we have the usual 120 degree currents and 60 degree voltages one would expect for delta metering. And we have the correct phase rotation.

But the client is unhappy saying the installation is not "standard" since the terminals on the test block, and on the drawings, labeled A are actually B, etc. It will cost big bucks to reconfigure the primary connections.

In my experience the choice of labelling of phases in metering is arbitrary and makes no difference to the meter readings. When I look in IEEE Standard C57.13 the diagrams (pgs 32 -37) do not label the phases so I would assume labelling is arbitrary.

Would anyone know of a standard or industry reference that states clearly whether labeling of phases for metering is arbitrary or not?

 

[ScottyUK]

Did the client approve the drawings for construction?


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If we learn from our mistakes I'm getting a great education!

 

[jghrist]

I don't think there is a standard. I do think that the labels and the drawings should be changed to reflect the actual phase arrangement. I get from your post, however, that the client will not accept that, but wants the connections changed.

 

[Zogzog]

Somewhere in a IEEE doc (Red book maybe) it says phaseing is labeled A-B-C (X-Y-Z) top to bottom, left to right, front to back, I will see if I can find the actual reference

 

[SSLA]

Folks:

Thanks for the replies. This seems to be a mystery area. Several times in the past we have had to transpose phases on the lateral run into a factory because all of the motors in the factory ran backwards. In these cases we left the metering as-is and in this case I think we should probably change the drawings. And yes the client did approve the drawings.

 

[rovineye]

Sounds like IEC equipment? Standard manufactured items I get from Europe, are usually phased U-V-W, which equates to A-C-B for correct rotation. I make the initial correction at the generator, and then after that, when viewed from the front, phasing is A-B-C from top to bottom, front to back, or right to left.

No reference or standard, as I am shipboard. It's just customary for me.

 

[ScottyUK]

U-V-W equates to A-C-B rotation? Can you expand a little on that comment - I am rather puzzled by it.

Thanks.


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If we learn from our mistakes I'm getting a great education!

 

[rovineye]

I tried to upload a document showing our generator windings and connections, but our security software prevents that. I will do it from home tonight.

I had thought the CCW convention was the same, but we have always made this phase swap, as originally directed by Alstom. When we get a motor from Europe, we again have to swap a phase at the motor to get correct rotation. I never did delve into it, because it works, and I have enough to keep me busy with things that don't work.

Somehow I though I might hear from you on this.

 

[slavag]

Hi.
U V W is A B C or R Y B or R S T or L1 L2 L3.
once I seid on generator label U V W eq L3 L2 L1 or T S R, but it was some espesial case ( I think it was synch motor used as generator).
on the meters also used labeles V1, V2, V3 and Vn or Vref.
same for currents I1, I2, I3 .
Regards.
Slava

 

[SSLA]

Folks:

I hope I did not confuse anyone. The metering was installed on an existing 46kV class overhead circuit mounted on wood poles. There would be no standard phasing as the circuit can be transposed at various points along the way such as turns and road crossings.

The actual phasing was unknown at design time. So we just designed the metering to install as efficiently as possible on the wood pole structure on the understanding that the metering would work properly even if the phases we labelled A-B-C on our drawings actually turned out to be different when phasing could be traced.

I think I would mark the drawings L1-L2-L3 next time to avoid this issue.

 

[rovineye]

This first few pics show the windings and star point connections. A-B-C/ U-W-V

http://files.engineering.com/getfil...300-4ead-8bb5-096ae5e3e3f2&file=Picture_1.png

http://files.engineering.com/getfil...c60-488d-ba69-1ca75d1e60b0&file=Picture_2.png

These drawing details show my bus layout and labeling inside the box for output cables and the internal start point connection. Same thing there.

http://files.engineering.com/getfil...79e-4458-b6c8-6e323d97725f&file=Picture_3.png

http://files.engineering.com/getfil...9dc-4329-8a4b-e2d61b84171b&file=Picture_4.png

Not driving the generator in the opposite direction or anything strange. At least not that I can think of. Phase rotation for sure is correct. I parallel with utilities frequently.

 

[alehman]

The meter should work regardless of the phasing. I think the issue is compliance with the owner's standards. If they want the CT's on A and C then, it seems like it would be your responsibility to design it that way or call for the installing contractor field verify the phase sequence before installing it.

 

[slavag]

Rovineve.
Thank you, it's intresting, first time I see this kind of labeling. I think French companies used other labeling too ( G... sometting). But actually is not so important, if all work and it's standars at your plant. More problematic if it's like to our case from this week.
60MVA trafo 170kV side U V W utilities connected to C B A and connected current circuits accorodantly and check all wiring. Other contractor 22kV side connected U V W as A B C
and connected current circuits accordantly too . Commissioning ( ....... I preffer w/o words) contractor
check all up to relays and meters and send report to customer "all checked". Customer order us for testing and
setting of protection relay only. We start test stability of trafo diff protection with 400V AC and I preffer not used at the forum words what I said to contractors, customer, etc.... In additional at the stability test time founded two open current circuits, was fun, but current was very small and not burn anything. Within two days we tested all current circuit again, change labeling and provided stability test again. But what is a situation: on the diff relay we have C A B rotation ( MV side) according to HV side and instead Yd11 of trafo at relay we put Yd1 group, and on metering and protection at the MV side we have A B C rotation according to trafo connection.
And bigest problem, I don't know if this kind of commissionning eng.... tested VA curves of CT's and all connected according to type of CT cores. Second part of those week was tested of voltage wiring at this project and i'm not used additional words...
And next, becouse some constraction mistake, coupler was turned to 180 deg and now in all cubicales phasing is A B C and at coupler is C B A, for synch. phasing we changed all voltage wiring. About tripping and interlocked scheme I'm not say anything, it's another story. After this project, if we finished it, possible write book.
O.K. now I feeling better and go write post to customer and my boss, what happend and why I request additional hours for the project and additional cost.
Regards.
Slava

 

[ScottyUK]

Interesting Rovineye.

Can anyone else in the US comment on whether this is normal? If it is then I guess we Europeans need to pay closer attention to terminal markings on equipment imported from the US. I have always believed that U-V-W and A-B-C were directly mapped to each other.

Wild guess: You haven't got a marine generator by any chance? Some of them are designed to rotate in the reverse mechanical direction to limit the effect of the reaction torque on the vessel. I would expect them to have the same electrical rotation though.


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If we learn from our mistakes I'm getting a great education!

 

[rovineye]

ScottyUK,
Built to NEMA MG1, but I don't have a copy to look at section 2.1.
They are marine generators (turning CCW as viewed from drive end), but they are used on UK as well as US vessels. So it puts us right back in the same discontinuity, but I don't think that rotation is unique anyway.

Slavag,
The generator design is French design if my memory serves me. Issues like you have can give a guy sleepless nights...

SSLA, Sorry to get off track from your OP. Clearly you are dealing with a different conflict.

 

[rovineye]

O.K.,
I woke up the designer and quizzed him on this. It looks like I was wrongs when I stated "Not driving the generator in the opposite direction or anything strange."

He fed me some history, which boils down to the Royal Navy turing this generator CW from driven vice my CCW from driven. So why have both phasings marked on the technical drawings, along with a single note that driven unit is CCW from driven end? At that point, due to it being the middle of the night there, he addressed in some unknown slang terms, none of whick I beleieve to be complimentary, and told me any additional information could only be passed along at the Owl and Squirrel Pub, while drinking on my tab.

That still leaves me with the mystery of my motors turning the wrong way when they are IEC, but I now question that statement by my hookup guys as well.

So we are back to what we all though to begin with, that we all have the same phase displacement rotation, we just can't decide to use the same markings.

 

[ScottyUK]

Is the generator still driven by its original engine, or have you married a generator to your own engine? The electrical rotation is likely to be correct U-V-W if the generator mechanical rotation is per design - is your engine running the generator in 'reverse' compared to original design? This might explain some of the strange goings on.



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If we learn from our mistakes I'm getting a great education!

 

[rovineye]

ScottyUK,
The generators are purchased without prime movers. We marry it up here with our MAN engine.

 

[Hoxton]

As regards the "different" phase rotation US vs Europe. I remember that there was a difference in the standards for morors & generators (IEC/BS) as against ANSI/NEMA for definition of phase rotation. I think the difference was that the standards viewed the drive end from opposite ends, so for the same winding the rotation was different for US & IEC.

I do not have acess to the standards any more, so I cannot verify if this is the case.

We had some generators for 50 / 60Hz stock & I think they were marked RYB / T3 T2 T1 or whatever - apparantly opposite phase rotation, but not actually, if you see what I mean!

Can anyone check this?