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The Natural Philosopher[_2_] The Natural Philosopher[_2_] is offline
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Default Overhead power cables.

On 05/01/18 11:02, Dave Liquorice wrote:
On Thu, 04 Jan 2018 11:47:09 +0000 (GMT), Dave Plowman (News) wrote:

Just how many time to these have to be replaced in a storm before they
get the message that they'd survive a storm if underground?

How unreliable do you think overhead is? Our supply is overhead from
the grid substation at Penrith (for the 33k V feed to the local
primary substation), 30 odd miles away. The back up 11 kV which runs
more or less parrallel with the 33 kV is derived at the Great Selkeld
primary (it's 33 Kv also coming overhead from Penrith). Both of these
feeds pass over Hartside at 2,000' and a few miles south of Great
Dunn Fell which recorded that 100 mph gust the other day (nothing
that unusual TBH, Great Dunn Fell is one of the windiest, if not the
windiest, place in the UK).

We used to get about one auto recloser trip a year, ie a couple of
seconds off when a branch (or WHY) touches the line, gets vapourised,
trips the auto recloser, that resets after a second or two. They seem
to have upped the tree cutting frequency in the last 5 years or so
and recloser trips are now less than one/year.

The longest outage we have had in nearly 20 years was after an ice
storm. That brought down quite a few sections of line and the recoil
snapped about 1/2 a dozen poles. Some of which supported an air
switch and line join/split. Took 'em 36 hours to plant the new poles,
insall air switch and re string. Overhead telephone lines (Dropwire
No.10) where encased in ice the best part of 2" in diameter,
stretched amazingly and recovered.

Of the other outages measured in a few hours, most have been plant
failures, transformer fire and a failed insulator, spring to mind.
Talking to others who live in towns, with underground supplies, some
have far more power problems than we do.

I'd say your experience is remarkably similar to mine

Used to be 2-3 a year, now down to less than one

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