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Registered Member #3040
Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237
Steve McConner wrote ...
Somewhere you really shouldn't have been. Maybe on the roof of a house under some power lines, on a really hot day, at half-time of the Cup Final?
It shouldn't have been inside one of the supergrid substations, because there are safety clearance rules in there that you're supposed to observe.
I was supposed to be there and it was an underground oil insulated/cooled cable in London. I was doing some tests on a leaky feeder comms system in the tunnel. I was with a National grid guy (obviously) and we had some emergency re-breathers with us but he did say that if we needed to use them we probably wouldn't get the chance ! He also reassured me that they weren't due another cable explosion just yet The tunnel was VERY warm and that was with the ventilation fans switched on. I am beginning to doubt whether it was a 400kV cable though, he defiantly told me it was a "supergrid" cable and this was the tunnel but I can only find references to 275kV cables. There were two levels of tunnel the upper one was apparently "grid" and the lower one "supergrid" ?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Oh, "line" means overhead line.
Scottish Power recently laid some 132kV cables down my street, why I have no idea. I certainly didn't order 132kV service. I'm sure a city the size of London will have 400kV ones.
Registered Member #3040
Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237
Incidentally there is a series of programs about the National grid still available for a few more days on iPlayer (UK only, sorry) I haven't seen them yet so don't know if they're any good.
Registered Member #1617
Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139
The photographer (in link within TDU's original post) writes: " you need lots of juice (735 000 Volts) cold weather, some humidity (rare over here!) that's why it took 25 years to see it again!"
I have some 66kv lines near my house, they have old porcelain suspension insulators on them, when there is a light rain/fog etc, they all hiss and crackle with corona, you can easily see the corona on the surface of the insulators too, when it is dark...
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Martin King wrote ...
Incidentally there is a series of programs about the National grid still available for a few more days on iPlayer (UK only, sorry) I haven't seen them yet so don't know if they're any good.
I've watched the first two now. They were pretty good, thanks for the heads up. No hardcore tech stuff, but interesting nonetheless. My favourite bit was the film of what happens inside the National Grid control room when Eastenders finishes.
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Corona on 750KV transmission line
The tunnel was VERY warm and that was with the ventilation fans switched on. I am beginning to doubt whether it was a 400kV cable though, he defiantly told me it was a "supergrid" cable and this was the tunnel 
