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Default Overhead power cables.

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?

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On Thursday, 4 January 2018 11:52:23 UTC, 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?


they already know
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The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.


£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding


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On 04/01/2018 15:36, Andy Burns wrote:
The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.


£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding


Not 11 kV though: 132 and 400 kV.

A bit more detail here

http://www.icevirtuallibrary.com/doi....2011.164.6.11

Tunnels were 4.15 and 2.8 metres diameter.

I guess trenched undersea cables are much more lossy. It would be
interesting to know at what point it becomes worth going to DC.
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In article ,
"Dave Plowman (News)" writes:
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?


Probably a lot. Undergrounding cables is much more expensive
than stringing overhead. Normally only done where there's a
legal requirement, or someone else pays them to do so.

--
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On 04/01/18 17:32, Andrew Gabriel wrote:
In article ,
"Dave Plowman (News)" writes:
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?


Probably a lot. Undergrounding cables is much more expensive
than stringing overhead. Normally only done where there's a
legal requirement, or someone else pays them to do so.


It depends. When I had my supply undergrounded in order to be able to
rebuild a 2 storey house, the received wisodm was that they were happy
to do it as the general policy was to underground as much 11kv as they
could.

The problem being theres a lot of it, its no higher than the trees by
and large, so it gets a lot of stick from lightning and from tree
branches falling.

33Kv and upwards I think they are less keen. And big 132/275kv pylons
are so far above tree level as to be uneconomic to underground.




--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

Ayn Rand.
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Now there are issues about this one. It seems that in the windiest places
the fix is to have the pylons closer together. This is done in some
countries, but it seems that in the same way we suffer from no snow ploughs
or whatever we refuse to do the correct engineering thing.#

We do not get ice storms and wind often enough to make it cost effective.
Of course underground also has its problems due to ground movement and the
need for extremely good insulation and thicker conductors as they will get
hotter.
I just think we have a history of not wanting to do things in an over
engineered fashion, but as the climate extremes get worse, somebody is,
eventually going to have to bite the bullet on all these things.
Has anyone heard of how many wind turbines were damaged by the storms of
the last few days. We know of course that they cannot be used in high winds
or for very gusty winds with variable direction.
Brian

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"The Natural Philosopher" wrote in message
news
On 04/01/18 14:12, newshound wrote:
On 04/01/2018 11:56,
wrote:
On Thursday, 4 January 2018 11:52:23 UTC, 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?

they already know

+1


cost of repairing overhead 11KV fault. £2000.

Cost of undergrounding it - £30,000 per kilometer.

Dave, lefty**** that he is, still thinks there is a magic money tree
somewhere that 'capitalists' have 'kept all to themselves'...

Bless.



--
Religion is regarded by the common people as true, by the wise as foolish,
and by the rulers as useful.

(Seneca the Younger, 65 AD)



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Default Overhead power cables.

Brian Gaff wrote

Now there are issues about this one. It seems that in the windiest places
the fix is to have the pylons closer together. This is done in some
countries, but it seems that in the same way we suffer from no snow
ploughs or whatever we refuse to do the correct engineering thing.#


We do not get ice storms and wind often enough to make it cost effective.
Of course underground also has its problems due to ground movement and the
need for extremely good insulation and thicker conductors as they will
get hotter.


I just think we have a history of not wanting to do things in an over
engineered fashion, but as the climate extremes get worse,


You donít know that.

somebody is, eventually going to have to bite the bullet on all these
things.


Or that either.

Has anyone heard of how many wind turbines were damaged by the storms of
the last few days. We know of course that they cannot be used in high
winds or for very gusty winds with variable direction.



"The Natural Philosopher" wrote in message
news
On 04/01/18 14:12, newshound wrote:
On 04/01/2018 11:56, wrote:
On Thursday, 4 January 2018 11:52:23 UTC, 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?

they already know

+1


cost of repairing overhead 11KV fault. £2000.

Cost of undergrounding it - £30,000 per kilometer.

Dave, lefty**** that he is, still thinks there is a magic money tree
somewhere that 'capitalists' have 'kept all to themselves'...

Bless.



--
Religion is regarded by the common people as true, by the wise as
foolish, and by the rulers as useful.

(Seneca the Younger, 65 AD)





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On 04/01/2018 15:36, Andy Burns wrote:
The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.


£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding


They did something similar in Barcelona when they had their Olympics
windfall IIRC. But not that deep - 30m?! Pretty much future proofs
infrastructure of this kind.

The private sector is not likely to take such a long-term view.

--
Cheers, Rob
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On 05/01/2018 09:17, RJH wrote:
snip

They did something similar in Barcelona when they had their Olympics
windfall IIRC. But not that deep - 30m?! Pretty much future proofs
infrastructure of this kind.

The private sector is not likely to take such a long-term view.

They had to go deep to get under stuff already there - eg the Channel
Tunnel Rail Link.

Of course it would have been cheaper to take the cables _over_ .....

--
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reply-to address is (intended to be) valid
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On 04/01/2018 11:47, 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?


And how many times do they have to be replaced when a JCB digs them up
before they get the message that they survive road/building work if kept
above ground where they can be seen?

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk
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On 05/01/18 09:17, RJH wrote:
On 04/01/2018 15:36, Andy Burns wrote:
The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.


£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding



That was presumably 132kV or greater though, not 11KV, which is more or
less a biggger version of 'armored mains cable'

They did something similar in Barcelona when they had their Olympics
windfall IIRC. But not that deep - 30m?! Pretty much future proofs
infrastructure of this kind.

The private sector is not likely to take such a long-term view.

National grid *is* private sector.

Their arttrtudue was that they would and coul afford to may abiut 35% of
te cist of undergriunding the lines over my house, if I could stump up
the remaining 18 grand or so.

In terms of increasing the property value it was worth every penny.



--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen
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On 05/01/2018 10:28, Huge wrote:
On 05/01/2018 09:17, RJH wrote:
snip

They did something similar in Barcelona when they had their Olympics
windfall IIRC. But not that deep - 30m?! Pretty much future proofs
infrastructure of this kind.

The private sector is not likely to take such a long-term view.


The private sector routinely deals with entities at least 100 years long
(leases, syndicated loans, etc.) whereas politicians are only interested
in the next election, so I suggest you wind your neck in.

ISTR the Channel Tunnel was also funded by the private sector: I
certainly lost money on it

--
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reply-to address is (intended to be) valid


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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.

--
Cheers
Dave.



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On 05/01/2018 10:59, Huge wrote:
On 2018-01-05, Robin wrote:
On 05/01/2018 10:28, Huge wrote:
On 05/01/2018 09:17, RJH wrote:
snip

They did something similar in Barcelona when they had their Olympics
windfall IIRC. But not that deep - 30m?! Pretty much future proofs
infrastructure of this kind.

The private sector is not likely to take such a long-term view.

The private sector routinely deals with entities at least 100 years long
(leases, syndicated loans, etc.) whereas politicians are only interested
in the next election, so I suggest you wind your neck in.

ISTR the Channel Tunnel was also funded by the private sector: I
certainly lost money on it


That was syndicated finance.


FTAOD I meant the public offer to raise share capital. I've never worked
in banking or institutional investment.

Donations welcome from those who did!


--
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reply-to address is (intended to be) valid
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On 05/01/18 09:50, alan_m wrote:
On 04/01/2018 11:47, 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?


And how many times do they have to be replaced when a JCB digs them up
before they get the message that they survive road/building work if kept
above ground where they can be seen?

In my case only once in 17 years and that was because an HGV drove over
the verge and punched a stone through the armour

All in all at the rural 11KV level accidents are far less frequent on
undergrounded cables

They are arguably far less dangerous too in a packed urban environment


I cant remember seeing an overhead 11KV in a major town


--
The biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

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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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On Thu, 4 Jan 2018 16:12:00 +0000, newshound
wrote:

On 04/01/2018 15:36, Andy Burns wrote:
The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.


£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding


Not 11 kV though: 132 and 400 kV.

A bit more detail here

http://www.icevirtuallibrary.com/doi....2011.164.6.11

Tunnels were 4.15 and 2.8 metres diameter.

I guess trenched undersea cables are much more lossy. It would be
interesting to know at what point it becomes worth going to DC.


65 miles is the worlds longest undersea AC cable (Blackpool - Isle of Man) but
is only 90kV. The distance / voltage for that project was as far as is both
technically feasible and financially viable.

Direct burial of supergrid circuits at 400kV AC under the sea doesn't happen in
the UK, the crossings that do exist are all in tunnels, with overheads for all
the others. For DC the cost of the AC/DC conversion stations nearly always swamp
the cable costs.

As an aside the Western HVDC interconnector (2.2GW) down the Irish sea from
Hunterston to Deeside working at 600kV (a new record for undersea HVDC) started
operation a month ago.

--


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On Fri, 5 Jan 2018 09:50:57 +0000, alan_m wrote:

On 04/01/2018 11:47, 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?


And how many times do they have to be replaced when a JCB digs them up
before they get the message that they survive road/building work if kept
above ground where they can be seen?


For the mobile crane driver that drove along the access road towards Hartlepool
Power Station, with the jib unlatched it can be safely assumed that he will
notice the overhead lines operating at 275kV the next time. The sound of a
dozen or so tyres exploding and craters being instantly formed in the road
surface while he shat himself in the cab will remind him too.

--
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On 05/01/2018 12:22, The Other Mike wrote:
On Thu, 4 Jan 2018 16:12:00 +0000, newshound
wrote:

On 04/01/2018 15:36, Andy Burns wrote:
The Natural Philosopher wrote:

cost of repairing overhead 11KV fault. £2000.
Cost of undergrounding it - £30,000 per kilometer.

£250m for 8 miles in Stratford

https://www.arup.com/projects/london-2012-powerlines-undergrounding


Not 11 kV though: 132 and 400 kV.

A bit more detail here

http://www.icevirtuallibrary.com/doi....2011.164.6.11

Tunnels were 4.15 and 2.8 metres diameter.

I guess trenched undersea cables are much more lossy. It would be
interesting to know at what point it becomes worth going to DC.


65 miles is the worlds longest undersea AC cable (Blackpool - Isle of Man) but
is only 90kV. The distance / voltage for that project was as far as is both
technically feasible and financially viable.

Direct burial of supergrid circuits at 400kV AC under the sea doesn't happen in
the UK, the crossings that do exist are all in tunnels, with overheads for all
the others. For DC the cost of the AC/DC conversion stations nearly always swamp
the cable costs.

As an aside the Western HVDC interconnector (2.2GW) down the Irish sea from
Hunterston to Deeside working at 600kV (a new record for undersea HVDC) started
operation a month ago.

Thanks, very interesting. (Probably off to the IOM in a couple of weeks).
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On 05/01/2018 12:23, The Other Mike wrote:
On Fri, 5 Jan 2018 09:50:57 +0000, alan_m wrote:

On 04/01/2018 11:47, 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?


And how many times do they have to be replaced when a JCB digs them up
before they get the message that they survive road/building work if kept
above ground where they can be seen?


For the mobile crane driver that drove along the access road towards Hartlepool
Power Station, with the jib unlatched it can be safely assumed that he will
notice the overhead lines operating at 275kV the next time. The sound of a
dozen or so tyres exploding and craters being instantly formed in the road
surface while he shat himself in the cab will remind him too.


:-)
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On 05/01/2018 12:23, The Other Mike wrote:
On Fri, 5 Jan 2018 09:50:57 +0000, alan_m wrote:

On 04/01/2018 11:47, 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?


And how many times do they have to be replaced when a JCB digs them up
before they get the message that they survive road/building work if kept
above ground where they can be seen?


For the mobile crane driver that drove along the access road towards Hartlepool
Power Station, with the jib unlatched it can be safely assumed that he will
notice the overhead lines operating at 275kV the next time. The sound of a
dozen or so tyres exploding and craters being instantly formed in the road
surface while he shat himself in the cab will remind him too.


For me, one of the amusing things about Hartlepool PS is the unique
"airlock" double gates arrangement for all vehicle access to site. Does
that say something about the perceived reliability of the local
population? These days of course most sensitive places have a gate plus
lifting barrier, and "chicane" access too, but back when it was first
built it gave the sensation of large American prisons.


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On 05/01/2018 11:52, The Natural Philosopher wrote:

I'd say your experience is remarkably similar to mine

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


We had 8 in 4 hours the other day. Only for a few seconds, but it still
reset all the clocks

Andy
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On Sat, 6 Jan 2018 22:15:56 +0000, Vir Campestris wrote:

I'd say your experience is remarkably similar to mine

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


We had 8 in 4 hours the other day. Only for a few seconds, but it still
reset all the clocks


Big branch that didn't get vapourised enough on first contact to not
make a second and not making contact frequently enough to lock the
auto-recloser out. I think the auto-reclosure in our line requires 3
trips within a minute before it locks out. ie
on-off-on-off-on-off-lockout.

If it had been mostly off with a few on seconds on, that would be the
DNO engineers trying to locate the fault by measuring ground
potentials/currents when they reconnect the supply and before it
trips again due to the fault. They'd almost located the faulty
insulator when we rang the DNO to say each time the power was
restored an insulator at the top of our pole arced over. This was
after a the best part of dozen short duration power restorations.

--
Cheers
Dave.



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