OT - power outage postcodes affected and explanation

[David]

We had a very brief power outage this morning.

Shortly after we received a phone message on the landline, and I received a text message on my phone. Both from UK Power Networks.

Nice to see some automated reporting of outages.

The report said that overhead high voltage line repairs had caused the outage.

The one thing that puzzled me was the three post codes reported to be affected. Ours (obviously), one next to us, and the third one in the countryside on the other side of the next town over. 15-20 miles away.

This looks to be a more likely place for overhead line problems because AFAIK there aren't any in our immediate vicinity.

Is there a reasonable explanation for an outage in two locations so far apart without any other postcodes in between being affected?

Cheers

Dave R

[Brian Gaff]

Well I have had this as well. It was about a year ago. Back then I was told that due to a problem elsewhere some areas were being routed around the issue. The new issue was that the bit that was now supplying more than it usually did, also failed giving the weird pattern of outages. The idea makes sense, but do we really have such a system that can route around underground faults like this. I noticed that the main road was dug up then for a month as I expect they had merely put off the work until the other bypass failed. Brian

[Dave Liquorice]

They certainly do at the 11 kV distribution level in rural areas as it's easy to follow the lines, see the air switches and what their normal state is. The distances involved means that the distribution is broken up into segments of a mile or three long and formed into large rings. Normally a "line" will be a number of segments with normally closed air switches between each segment. Where two lines would join to form a ring the air switch is normally open.

ASCII art follows:

ARC - Auto Recloser C - Normally closed switch O - Normally open switch EOL - End of line

Primary ----- Line A ----- ARC ----- C ----- C ----- C --+-- EOL | O | Sub ----- Line B ----- ARC --- C ----- C --+-- C ----+--- EOL | O | Station ----- Line C ----- ARC --- C ----- C --+--- EOL

Any given segment can be isolated and any line can be fed from the "other" end.