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#141123 06/18/04 10:51 AM
Joined: Oct 2003
Posts: 25
R
Member
I believe that our phases are arranged as R-Y-B.

All the 11kV poles around here have small coloured plates about half way down the pole, with the phase colours arranged on them that way.

Await some pictures.

#141124 06/19/04 12:31 PM
Joined: Apr 2002
Posts: 2,527
B
Moderator
I must correct my statement. Four bell insulators for “35kV-class” lines would be routine here too.

#141125 06/19/04 05:09 PM
Joined: May 2004
Posts: 186
A
Member
If the 11Kv poles currently have RYB markers, I would have thought that if new ones are installed or replacement takes place they will follow the L1 L2 L3 Format or Brown,Black,Grey. I thought we has some link with Europe anyway on the HT side,

#141126 06/19/04 06:32 PM
Joined: Aug 2001
Posts: 7,520
P
pauluk Offline OP
Member
The present red/yellow/blue markers can still be distinguished fairly easily even when well-weathered after being out in the British climate for many years.

If we do change on HT, then I don't see brown/black/gray being anything like as easily distinguishable. That alone seems like a good enough reason to me to retain our existing RYB system.

#141127 07/04/04 08:43 AM
Joined: Jun 2004
Posts: 15
T
Member
I work in the north of england.A while back someone told me that phase rotation is incorrect in merseyside. Id forgoten till I did a 3-phase ac in chester. On completion the unit would not run. When i checked rotation it WAS incorrect, therfore I swapped 2 phases at the origin and hey presto! Has anyone heard of this before, does it exist anywhere else and how did hit happen in the first place?
Thanking you!

#141128 07/04/04 11:44 AM
Joined: May 2004
Posts: 186
A
Member
Can not quite get to grips with what your saying there Teach. as part of an overall network can not imagine how Mersyside can have different phase rotation to the rest of the U.K. The consequenses dont bare thinking about.

#141129 07/04/04 02:11 PM
Joined: Aug 2001
Posts: 7,520
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pauluk Offline OP
Member
It seems highly unlikely that there could be a big phase-rotation problem over a large area of the network. The large number of interconnects on the HV transmission system would surely make this impossible.

I'd say it's more likely that the phase identification could be wrong within a small area, e.g. a neighborhood 11kv-to-240/415V xfmr incorrectly wired.

Even then though, you'd have to have two phases "crossed over" for there to really be a problem. Just "rolling" three around in sequence would be unlikely to cause any trouble.

For example, if R-Y-B is cross-connected to Y-R-B, there is a problem. But if R-Y-B is connected as Y-B-R, the phases won't correspond with others in the district but motors will still turn the right way as the rotation is still essentially correct. just with all phases displaced by 120 degrees compared to the correct wiring.

#141130 07/04/04 03:16 PM
Joined: Jun 2004
Posts: 15
T
Member
I take on board what you say guys
Im just a contracting animal and know little about supply. Since its happened to me ive mentioned it to a few people and it seems to be well known of up this end
While we talk supply id love to know something about this.....
When i look at a pylon i see three sets of wires RYB- right. Also there appears to be an earth wire connecting the tops of the pylons. Now my question is this ,where is the neutral. I assume the network must be in delta and the end of use substations are delta/star?
thanking you all in anticipation!

#141131 07/04/04 04:55 PM
Joined: Aug 2001
Posts: 7,520
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pauluk Offline OP
Member
The British HV system doesn't distribute a neutral, so as you say, the primaries of transformers are wired delta. (Or tapped across two of the three phases for single-phase, such as to feed one or two remote houses.)

This is somewhat in contrast with the North American arrangement where in many systems a neutral is distributed, thus allowing single-phase transformers to be wired phase-to-neutral or phase-to-phase.

Running a single-phase branch as one phase plus neutral to a remote point has certain economies, both in the pole equipment and in the fact that the 1-ph transformer needs only a single high-voltage bushing.

The line economies may well add up when you consider that the North American network has to cover many more miles into much more remote territory than anything we have in Britain.

#141132 07/04/04 06:00 PM
Joined: Jun 2004
Posts: 15
T
Member
thanks paul
now the next thing is this....
If they are wired in delta that would mean they are electrically separate from earth,so whats the point in earthing the pylons.Am i right in thinking that there would be no potential to earth???

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