power cuts

[Steve]

not really DIY, but we had a power cut earlier, during a particularly ferocious thunderstorm. Perhaps someone could tell me why it took the DNO only 20 seconds to restore power. I wouldn't mind, but after the power came back on, the thunder then got 10 times worse, for about half an hour, with no more disturbances! What caused / restored this power cut? I believe the power was cut on all 3 phases in our locality for the 20 secs, the local shop's power went out too.



One of my mates was inside a lift in the frenchgate centre in doncaster, when the power was cut to the WHOLE CENTRE! Somehow they freed him. But my mum was in debenhams and the EM lights werent working so they made them stay in the cafe where theres windows until the decision was taken to escort the crowd out thru the fire escapes.

 

[JohnD]

I was in Debenhams when the power went, and I was trapped for two hours on the escalator.

 

[Adam_151]

I was in Debenhams when the power went, and I was trapped for two hours on the escalator.

 

[JohnD]

 

[plugwash]

not really DIY, but we had a power cut earlier, during a particularly ferocious thunderstorm. Perhaps someone could tell me why it took the DNO only 20 seconds to restore power. I wouldn't mind, but after the power came back on, the thunder then got 10 times worse, for about half an hour, with no more disturbances! What caused / restored this power cut? I believe the power was cut on all 3 phases in our locality for the 20 secs, the local shop's power went out too.

There are theese lovely things called autoreclosers. A set time after breaking a fault they will restore power, if the fault has cleared (or was blown clear during the previous trip) then power is restored, if not then it will trip again. This may repeat several times before either power is restored or the retry limit runs out.

given there was a storm the initial fault was probablly a (wet) tree branch or similar item falling on a line and shorting it out momenterally.

 

[Steve]

There are theese lovely things called autoreclosers. A set time after breaking a fault they will restore power, if the fault has cleared (or was blown clear during the previous trip) then power is restored, if not then it will trip again. This may repeat several times before either power is restored or the retry limit runs out.

given there was a storm the initial fault was probablly a (wet) tree branch or similar item falling on a line and shorting it out momenterally.

nice one. Where are these located on the distribution grid? Reason i ask is your reasoning for the fault - tree branches. AFAIK, all the power AFTER the local substation (230v) is underground in our area, so it must have been before the local substation, unless the sudden downpour affected the integrity of the underground electrics.

 

[plugwash]

i belive they are mainly used on medium voltage (3 horizontalaly spaced wires on wooden poles)

 

[Lectrician]

They are used on the 33 and 11 kv lines. They are designed to keep supplies online, but are not very well suited when a fisherman tangles with a pole, or a JCB driver..........


There are also surge arrestors on the lines which open circuit on voltage surge - lightning hitting line directly will cause them to open for a several seconds - and at times, they will be clean-opened, and can then only be manually reset.

 

[Job_n_knock]

Typical eh? ........Debenham's E.L. not working. These companies penny pinch by cutting down on basic maintenance.

 

[SparkyMarky]

Here you go. I knew I'd seen some info on this somewhere:

http://www.edfenergy.com/core/factsheets/docs/whatcausesshortpowercuts.pdf

I never thought I'd see the day when EDF would come up with something worthwhile

 

[RF Lighting]

Thanks, that is quite an interesting read.
I'm not sure if the bloke with the big stick is trying to fry himself though.

 

[ban-all-sheds]

Interesting videos: (click the images. Those still on steam-powered internet should exercise caution and go via the website where they tell you how big the videos are)





details: http://205.243.100.155/frames/longarc.htm#Disconnect

 

[RF Lighting]

The exploding substation is pretty damned impressive, yet quite scary at the same time.

 

[SparkyMarky]

Wow. I could watch those clips for hours. The maintenance workers on the 500kV disconnect switch must have nerves of steel though. They're stood there calmly watching (apart from the guy at the front of the truck who has the sense to duck), whereas I'd have been giving it some legs in the other direction long before the arc was extinguished!

 

[ban-all-sheds]

Wow. I could watch those clips for hours.

It's the sound I can't get over. Somehow you just know it's a noise that you really shouldn't be hearing.

The maintenance workers on the 500kV disconnect switch must have nerves of steel though.

Or brains of wood....