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#133214 - 07/07/02 11:25 AM U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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]

[Linked Image]

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]

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]

[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).]


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#133215 - 07/07/02 11:29 AM Re: U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
[Continued...]

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

[Linked Image]

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

[Linked Image]

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]

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]


#133216 - 07/07/02 12:48 PM Re: U.K. Pics: Distribution  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
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.


#133217 - 07/07/02 04:10 PM Re: U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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]

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.


#133218 - 07/07/02 05:31 PM Re: U.K. Pics: Distribution  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
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.


#133219 - 07/08/02 07:05 AM Re: U.K. Pics: Distribution  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
do i see 'CT's ???

[Linked Image]


#133220 - 07/08/02 06:04 PM Re: U.K. Pics: Distribution  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
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]


#133221 - 07/09/02 05:59 PM Re: U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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.


#133222 - 07/10/02 07:52 PM Re: U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Here are our standard 240/415V Wye system neighborhood distribution lines:
[Linked Image]

[Linked Image]

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).]


#133223 - 07/13/02 04:06 PM Re: U.K. Pics: Distribution  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
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]

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

Another 3-phase xfmr, this time on a double-pole:
[Linked Image]

These are the three fuse/cut-outs on the 240/415 side:
[Linked Image]

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]


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