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Posted By: pauluk U.K. Pics: Distribution - 07/07/02 03:25 PM
I've finally got a digital camera working here, so here are a few quick photos from around the neighborhood to start you off.

First, a couple of shots of typical local MV power lines in a rural area:

[Linked Image from members.aol.com]

[Linked Image from members.aol.com]

Here's a typical 3-phase pole-mounted xfmr, again as found in rural areas to feed a small group of houses. The primary side is 11kV delta:

[Linked Image from members.aol.com]

And here's the secondary side, 240/415V Wye. I'm afraid this one didn't come out too well, but you can just make out the three fuse pull-outs on the pole:
{Edit: Image replaced with a better one!}
[Linked Image from members.aol.com]

[Continued next message]

[This message has been edited by pauluk (edited 07-07-2002).]

[This message has been edited by pauluk (edited 07-07-2002).]
Posted By: pauluk Re: U.K. Pics: Distribution - 07/07/02 03:29 PM
[Continued...]

Where power is needed for more than just a handful of houses, we normally have an enclosed sub-station, like this:

[Linked Image from members.aol.com]

A close-up of the current-style warning notice on the gate:

[Linked Image from members.aol.com]

And finally for now, here's the 3-phase xfmr within this particular enclosure (again, this is 11kv Delta to 240/415V Wye):

[Linked Image from members.aol.com]

I had to climb onto that adjacent wall to get this last shot. The neighbors started to wonder what I was up to! [Linked Image]
Posted By: Bjarney Re: U.K. Pics: Distribution - 07/07/02 04:48 PM
paul— On the pole-mounted unit, how far would you have to travel to disconnect the transformer’s [11kV?] high side? Inclusion of primary fused cutouts here look like the only significant difference. In the US, there have been “CSP” transformers in service, but tend to be fading in popularity. {Completely Self-Protected…}

The second “padmount” image would be real common where feeding a building or two on a college campus, but it would not likely be utility-owned.

Having semi-universal 415Y/240V would simplify things a bit. Here, you can get 120/240V 3w [~10-50kVA 1ø] 208Y/120V 4w [>45-500kVA 3ø] or 480Y/277V 4w [~75-3750kVA 3ø] for likely the same range of loads. In a lot of the US, the relative need for air conditioning most typically drives transformer sizes.

Utilities often install 1ø or 3ø “low-rise” padmount transformers, but with thousands of separate utilities, practices vary widely.

On the nosey neighbors, I would be tempted to knock on the door and apologize for the inconvenience, but you are merely conducting a recently mandated preliminary assessment of inhabited structures that would need to be rebuilt following a tank rupture.
Posted By: pauluk Re: U.K. Pics: Distribution - 07/07/02 08:10 PM
I went back to the pole-mounted xfmr this evening and managed to get a better shot with the light at a different angle, so I've replaced the image.

Also, here's a closer view of some MV lines that's a little better. You can see 11kV lines looking exactly like these in almost any rural part of Britain:
[Linked Image from members.aol.com]

Scott,
I'm not sure where the nearest isolator is for the pole-mount xfmr pictured. It's run from the spur line you can see coming off the pole in the second photo. There's a pole switch on that through-line about 200 yards from that spur, but I'm not actually certain which way the juice is being fed along the line at that point. Somewhere near the isolator is another spur to the edge of the settlement, from which the line goes underground for about 100 yards to the enclosed sub-station. I'll see if I can trace the lines when I get a chance.

The neighbors are all right really, as they know me, and this xfmr station is almost on my doorstep. (Honest officer, I was just taking pictures of electrical equipment to show some guys in America! [Linked Image]).

All of these pics so far are from within about 400 yards of my house. As I'm in a rural area right on the coast, it's kind of the end-of-line for power distribution, so there's nothing above 11kV for several miles.
Posted By: Bjarney Re: U.K. Pics: Distribution - 07/07/02 09:31 PM
Paul-- the primary isolation matter was just a question of curiosity more than anything. Line-clearance practices can be expected to be different everywhere—but based on longstanding, well-understood procedures that get us to accomplish tasks safely and consistently. Differences don’t necessarily make something right or wrong—safe or unsafe.

In overhead systems being able to be in sight of a visible open is desirable, but with underground circuits and metal-enclosed gear, it gets a bit more grey, and measures change accordingly. For given conditions, the most important thing can be that everybody’s on the same page of the manual, so to speak.
Posted By: sparky Re: U.K. Pics: Distribution - 07/08/02 11:05 AM
do i see 'CT's ???

[Linked Image]
Posted By: Bjarney Re: U.K. Pics: Distribution - 07/08/02 10:04 PM
Here is a local version [norcal] of that 240V 4-w∆ service. I believe the middle pot is 100kVA, and the others are 75kVA each—with a 12,470V∆ primary. It feeds a welding-fabrication shop, and normally the load would mandate 480V service, but I believe they wanted to be able to use older 240V-only welders, and the local irrigation-district utility cut ‘em some slack.

[Linked Image from 67.115.161.42]
Posted By: pauluk Re: U.K. Pics: Distribution - 07/09/02 09:59 PM
It's amazing just how many subtle differences there are between countries which give the place a different "feel." Different road signs and markings, different building styles, and for us technical types, the different types of transformers and switchgear by the roadside. That pic of yours just couldn't be England!

Steve,

I'm not especially familiar with all of this big distribution stuff, but so far as I'm aware there are no CTs on this local distribution equipment. There probably are some where these 11kV feeders come out of the area sub-station.
Posted By: pauluk Re: U.K. Pics: Distribution - 07/10/02 11:52 PM
Here are our standard 240/415V Wye system neighborhood distribution lines:
[Linked Image from members.aol.com]

[Linked Image from members.aol.com]

The neutral is usually the bottom line of the four. (The other cables below on these poles are telephone.)

These overhead LV systems are gradually disappearing in favor of underground cables. Even new services tapped off of these overhead lines are often run as underground feeders from the nearest pole. In general, a larger proportion of lines are underground here compared to the United States. Even the feeders to these overhead lines are actually run underground from the pad-mount transformer pictured above.

I'll try to get some photos of service drops and metering equipment when I get time and post them in a new thread.


[This message has been edited by pauluk (edited 07-10-2002).]
Posted By: pauluk Re: U.K. Pics: Distribution - 07/13/02 08:06 PM
A few more pics for all you HV enthusiasts. [Linked Image]

This is the type of small 1-phase xfmr used where one or two houses stand on their own. The incoming high-line is a two-leg spur from a normal 11kV delta:
[Linked Image from members.aol.com]

Here is an 11kV overhead switch, and you might be able to see that at this point the line goes underground:
[Linked Image from members.aol.com]

Another 3-phase xfmr, this time on a double-pole:
[Linked Image from members.aol.com]

These are the three fuse/cut-outs on the 240/415 side:
[Linked Image from members.aol.com]

And finally, some 33kV feeders into the area. The design of the poles and supports is fairly well standardized, so you could see something like this almost anywhere in the country:
[Linked Image from members.aol.com]
Posted By: Trumpy Re: U.K. Pics: Distribution - 09/08/02 04:12 AM
Paul,
Is the primary side of the Xformer fused
at all?.
Over here, we have all transformers,
connected to the Network(National Grid),
supplied through DDO (Dominion-Drop-Out)
fuses, these are a high voltage fuse,
which when it 'blows', will drop and hang
downwards, to make replacement easier,
and also identification of a faulty
circuit, a lot easier, especially at night.
These types of fuses are used on all
take-off points, from 3.3kV,6.6kV and 11kV
lines, normally they have a maximum current
rating of 10 amperes.
You want to replace one of these, with a
fault still in the Xformer, have never
done it myself, but I have heard from those that have, apparently,it rained fire.
Posted By: pauluk Re: U.K. Pics: Distribution - 09/08/02 01:18 PM
The only 11kV system I've worked with was a private facility (GPO/British Telecom), so I'm afraid I don't have a great deal of knowledge on the HV distribution side of things.

As far as I can tell though, there are no primary fuses on any of the 11kV-to-240/415V pole transformers.
Posted By: ChrisO Re: U.K. Pics: Distribution - 09/09/02 12:16 AM
there are no primary fuses on any of the 11kV-to-240/415V pole transformers.

Aha...that'll be why they explode (round here) and set fire to things
Posted By: Hutch Re: U.K. Pics: Distribution - 09/09/02 01:41 AM
Trumpy, Your DDO drop fuses sound exactly like those used in South Africa. One could always tell which one had blown. Worked as good isolators using a fibre-glass pole and hook.

[This message has been edited by Hutch (edited 09-08-2002).]
Posted By: pauluk Re: U.K. Pics: Distribution - 09/09/02 08:13 PM
Chris,
I don't recall exploding transformers where I lived in Cornwall, but we had fairly frequent outages during the winter. If I remember correctly, we took power from a major sub-station at, I believe, Indian Queens (that always struck me as being a very non-British-sounding place name!).

I don't know if any more distribution has been put underground since then and improved the situation somewhat -- I left in 1986.
Posted By: ChrisO Re: U.K. Pics: Distribution - 09/10/02 12:12 AM
Thnx for the Email.

>I don't recall exploding transformers >where I lived in Cornwall, but we had >fairly frequent outages during the winter.

We suffer badly from winter outages still - millions of Starlings roosting on lines at Marazion, goes on from 4:30 till about 6:00...the sky literally turns black when they arrive - an amazing sight.

>If I remember correctly, we took power >from a major sub-station at, I believe, >Indian Queens (that always struck me as >being a very non-British-sounding place >name!).

The story goes that Indian Queens is reputedly named after Pocahontas, the American Indian princess, who visited England in 1616 with her husband, John Rolfe, a colonist. She died here a year later at just 23 years of age.

>I don't know if any more distribution has >been put underground since then and >improved the situation somewhat -- I left >in 1986.

Mostly overhead - the only underground work here has been the laying of vast amounts of communications cable which I'd bet ends up at Goonhilly or possibly at all the American comms places down here.

Got your Milwaukee drill yet - if not CPC have just got them in their catalogue www.cpc.co.uk
or 08701 20 25 30
they are a subsidiary of Farnell (similar range) but cheaper and also sell spares for white/brown goods.

Chris
Posted By: pauluk Re: U.K. Pics: Distribution - 09/10/02 10:07 PM
I used to go down to Marazion occasionally; went across to St. Michael's Mount a couple of times, and remember getting my feet wet trying to beat the tide once!

I haven't ordered the drill yet; I've been waiting to see if there was anything else to order at the same time to combine the shipping charges. I didn't realize there were any U.K. firms handling Milwaukee products. I'll check that site out -- Thanks.
Posted By: sparky66wv Re: U.K. Pics: Distribution - 09/10/02 10:48 PM
Living just south of Pocahontas County, WV...

I thought she married John Smith?

Or was that just the Disney version of history?

*walks away embarrassed by my ignorance...*
Posted By: pauluk Re: U.K. Pics: Distribution - 09/10/02 10:53 PM
Hey Virgil,
I meant to mention that as I remember seeing Pocahontas Co. in my road atlas and in a WV Tourist Guide.

Looks from the map as though it's a nice sparsely populated county up in them thar hills.
Posted By: Trumpy Re: U.K. Pics: Distribution - 09/11/02 07:11 AM
Hey Guys,
Just to get back to the topic,
The only reason why I mentioned Lineside
fuses, was because, not only do our
Supply Regulations require them,
but, locally, we have a problem, with
Sea-birds looking to roost upon the
Xformers(being warm), but they get their
wings caught in the feeder wires, fed from
the DDO fuse, to the Xformer.
This only happens, when the sea is very
rough, thankfully this only happens a
few times a year.
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