http://www.glumbert.com/media/highpower

mark

On 28 Jan, 00:14, "mark" wrote:
http://www.glumbert.com/media/highpower

Some oddities here - I'm not sure he really knows what a Faraday cage
is.

But that aside, since the helicopter gets brought to the same
potential as the power lines, I presume this is high voltage DC
transmission. I wonder where it is?

Ian

On Mon, 28 Jan 2008 00:14:04 -0000, "mark"
wrote:


http://www.glumbert.com/media/highpower

_sort_ of d-i-y, innit...

--
Frank Erskine

In message , mark
writes


http://www.glumbert.com/media/highpower

mark


Yeah, it's been posted several times over the past couple of years


--
geoff

In message
, The
Real Doctor writes
On 28 Jan, 00:14, "mark" wrote:
http://www.glumbert.com/media/highpower

Some oddities here - I'm not sure he really knows what a Faraday cage
is.

But that aside, since the helicopter gets brought to the same
potential as the power lines, I presume this is high voltage DC
transmission. I wonder where it is?

Canada IIRC

--
geoff

geoff wrote:

transmission. I wonder where it is?

Canada IIRC

Got a US flag on his shoulder... could be the Massachusetts end of the
line from Ayer in the US to Quebec:

http://en.wikipedia.org/wiki/Quebec_...d_Transmission



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Jan 28, 3:49*am, geoff wrote:
In message , mark
writes

http://www.glumbert.com/media/highpower

mark

Yeah, it's been posted several times over the past couple of years

--
geoff

Doubt if it is DC. Most transmission lines in NA are AC as far as I
know, especially since the Canada-US systems are intertwined and share
power on linked grids.
This is the scheme where a helicopter borne worker first hooks on then
transfers himself to the live transmission wire in order to work on
the connections, separators, insulators etc.?
Thre is some talk of transmitting electrical power from the proposed
Lower Churchill generating site in Newfoundland, Labrador across to
the island portion of that province, then some 80 miles across the
Gulf of St. Lawrence to Nova Scotia, New Brunswick and New York
State.
Due to the long underwater link would think DC would be used there;
with converters at each end.
By the way. In that vein (DC underwater cables); anybody know the
answer to this question .....?
"There was or is a DC power cable across the north of the North Sea
beween Scotland and Norway????" Purpose of which to share power
between those two countries which have hydro generating capabilities.
Seem to remember reading about it in the mid 1950s.

snip
"There was or is a DC power cable across the north of the North Sea
beween Scotland and Norway????" Purpose of which to share power
between those two countries which have hydro generating capabilities.
Seem to remember reading about it in the mid 1950s.


ISTR the cross-channel link to France was the announced as the first
UK-Europe power sharing. And that seems to be confirmed by a quick
Google which brings up the history here with no mention of Scotland
until 2001 to NI
http://www2.theiet.org/oncomms/secto...53EE3D46B2112D


--
Robin

neverwas wrote:
snip
"There was or is a DC power cable across the north of the North Sea
beween Scotland and Norway????" Purpose of which to share power
between those two countries which have hydro generating capabilities.
Seem to remember reading about it in the mid 1950s.


No way.

ISTR the cross-channel link to France was the announced as the first
UK-Europe power sharing. And that seems to be confirmed by a quick
Google which brings up the history here with no mention of Scotland
until 2001 to NI
http://www2.theiet.org/oncomms/secto...53EE3D46B2112D


Yes. I visited it in the 60's and it was as far as I know the ONLY
external grid link in the UK at that time, and as far as I know still is.

Things that stand out from the visit.

- a room, a very large room FULL of thyratron valves ..each one about 8
foot tall.

- about 6 acres of capacitors to smooth the output.

- Some inductors the size of houses for the same purpose..

- "we can draw a 30KV arc off the line for several hours after
switchoff" from the engineer showing us round.

A technical marvel, and JUST ABOUT worth it economically.

I found a couple of references to linking the Orkney and Shetlands using
undersea cables (under consideration): Currently the largest is IIRC in
the USA ad is 65m long. National grid had(has?)plans to do a half a
billion quid one of a gigawatt capacity to Holland. That is the same
order of cost as a half gigawatt power station..

Cost are somewhere near a million quid a mile. More for larger power
levels like the above.

No references to any scotland- Morway links tho.

In message , mark
writes


http://www.glumbert.com/media/highpower

Am I the only person who thinks that's clearly CGI ?

--
Si

Si wrote:
In message , mark
writes


http://www.glumbert.com/media/highpower

Am I the only person who thinks that's clearly CGI ?

I think its for real, but whether the cables are on, and whether you can
do more than make a cursory inspection, if they are , is a moot point.

The arc drawn looks clearly DC...sort of what might be left on a 132KV
line if the contactors flipped out.

On Mon, 28 Jan 2008 14:23:38 +0000, The Natural Philosopher wrote:

Si wrote:
In message , mark
writes


http://www.glumbert.com/media/highpower

Am I the only person who thinks that's clearly CGI ?

I think its for real, but whether the cables are on, and whether you can
do more than make a cursory inspection, if they are , is a moot point.

The arc drawn looks clearly DC...sort of what might be left on a 132KV
line if the contactors flipped out.


Just for reference...

http://www.youtube.com/watch?v=PXiOQCRiSp0

The Natural Philosopher wrote:


I think its for real, but whether the cables are on, and whether you can
do more than make a cursory inspection, if they are , is a moot point.

I am sure it is real the circuit is not complete (no earth) so NO
current will flow. seem to remember watching a documentary about this
(the "linesman" stayed on the helicopter platform though) it was "just"
an inspection but there seemed to be no fear of touching the wires.
C.F. Birds CAN sit on power lines without getting zapped (or there would
be lots of dead bird bodies under power lines) but the difference in
voltage gives them a slight tingle which they don't like so they tend
not to perch on power lines.

The arc drawn looks clearly DC...sort of what might be left on a 132KV
line if the contactors flipped out.

Isn't the arc caused by current flow from the helicopter ? Helicopters
can work up a fearsome static PD hence the guys that attach loads to
military helicopters touch the load strop with a grounded pole first.
In a SAR situation allow the winchman to touch the ground/sea first do
not try to grab him (he will probably have some sort of "earthing wire"
running through his harness). If your life depends on it grab the strop
or WHY and take the belt, it is non lethal it just can be very painful
A thread that talks about helicopter static build up:-

http://preview.tinyurl.com/32u6gq

PCPaul wrote:
On Mon, 28 Jan 2008 14:23:38 +0000, The Natural Philosopher wrote:

Si wrote:
In message , mark
writes

http://www.glumbert.com/media/highpower

Am I the only person who thinks that's clearly CGI ?

I think its for real, but whether the cables are on, and whether you can
do more than make a cursory inspection, if they are , is a moot point.

The arc drawn looks clearly DC...sort of what might be left on a 132KV
line if the contactors flipped out.


Just for reference...

http://www.youtube.com/watch?v=PXiOQCRiSp0

Thiose isolators are NEVER opened under load though. They have oil
filled contactors to actually break the circuits. Those are
isolators..thats just redsidual cable capaitance being broken.

soup wrote:
The Natural Philosopher wrote:


I think its for real, but whether the cables are on, and whether you
can do more than make a cursory inspection, if they are , is a moot
point.

I am sure it is real the circuit is not complete (no earth) so NO
current will flow. seem to remember watching a documentary about this
(the "linesman" stayed on the helicopter platform though) it was "just"
an inspection but there seemed to be no fear of touching the wires.
C.F. Birds CAN sit on power lines without getting zapped (or there would
be lots of dead bird bodies under power lines) but the difference in
voltage gives them a slight tingle which they don't like so they tend
not to perch on power lines.

The arc drawn looks clearly DC...sort of what might be left on a 132KV
line if the contactors flipped out.

Isn't the arc caused by current flow from the helicopter ? Helicopters
can work up a fearsome static PD hence the guys that attach loads to
military helicopters touch the load strop with a grounded pole first.
In a SAR situation allow the winchman to touch the ground/sea first do
not try to grab him (he will probably have some sort of "earthing wire"
running through his harness). If your life depends on it grab the strop
or WHY and take the belt, it is non lethal it just can be very painful
A thread that talks about helicopter static build up:-

http://preview.tinyurl.com/32u6gq

Yes, but those cables are NOT running at full AC.

Its static off disconnected cables and the chopper you are seeing.

AFAIAW teh sequenc to service cable is

- blow the contactors. These are ****ING great switches in tanks of
inert oil designed to quench sparks.

- open up the isolators - drawing a bit of an arc as you do, depending
on leakages.

- go to section of line and throw an earth strap over it to get rid of
static and KEEP it that way. Once isolated it can pick up a lot of static.

- THEN put a man on it.

I reckon it's AC.

After he's clipped on and climbed onto the wire, he pulls the clip off
and the chopper flies off. How could it *not* be at line voltage after
being clipped on?

OTOH, if the line was running AC at an appreciable voltage you'd need a
current flow to charge/discharge the helicopter-capacitor with each cycle.

The arc on departure runs to a couple of feet. IIRC 1000V per inch - so
the line is at 24kV plus. I can't say *how* much plus, the chopper
isn't earthed very well...


Andy

The Natural Philosopher wrote:

The arc drawn looks clearly DC...

You sure? If it were DC the helicopter would just charge up to a
constant voltage and the arc would cease - no further charge to
transfer, unless there's corona discharge from the rotor tips, or unless
it's very ripply DC (unlikely with polyphase rectification).

That arc seems fairly sustained, as you'd expect with AC , and a 120 Hz
buzzing seems to accompany it.

--
Andy

In article ,
The Natural Philosopher writes:
PCPaul wrote:
http://www.youtube.com/watch?v=PXiOQCRiSp0

Thiose isolators are NEVER opened under load though. They have oil
filled contactors to actually break the circuits. Those are
isolators..thats just redsidual cable capaitance being broken.

I saw a detailed write-up of that (and I've got a much
better quality video of it). It's a sulphur heaxafluoride
(SF6) breaker switch, not oil. The nearest SF6 breaker
is half jammed, leaving the isolator as the only means
of breaking it. When the SF6 breaker fires, you see the
arc flash across the half of the SF6 breaker which does
open, because the other half is still jammed closed.
That starts the arc across the isolation gap.

This switch switches the line inductors in/out at the
end of a long transmission line which are correcting
for the line capacitance. It's not actually carrying
the line current.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Mon, 28 Jan 2008 19:51:36 +0000, The Natural Philosopher wrote:

http://www.youtube.com/watch?v=PXiOQCRiSp0

Thiose isolators are NEVER opened under load though. They have oil
filled contactors to actually break the circuits. Those are
isolators..thats just redsidual cable capaitance being broken.

There is more about that arc if you dig about on the web rather than the
few words on yewtube.

http://www.arcfault.org/video.htm

Fascinating stuff.

--
Cheers
Dave. pam is missing e-mail

On Mon, 28 Jan 2008 21:08:38 +0000,it is alleged that Andy Champ
spake thusly in uk.d-i-y:

I reckon it's AC.

After he's clipped on and climbed onto the wire, he pulls the clip off
and the chopper flies off. How could it *not* be at line voltage after
being clipped on?

OTOH, if the line was running AC at an appreciable voltage you'd need a
current flow to charge/discharge the helicopter-capacitor with each cycle.

The arc on departure runs to a couple of feet. IIRC 1000V per inch - so
the line is at 24kV plus. I can't say *how* much plus, the chopper
isn't earthed very well...


Andy

Judging by the shot of the long string of cap and pin insulators
visible at the end, somewhere in the low hundreds of kV

--
_
( ) ASCII ribbon campaign against html e-mail
X and usenet posts
/ \

On Mon, 28 Jan 2008 00:14:04 -0000, "mark"
wrote:



http://www.glumbert.com/media/highpower

mark


Nothing new there. The UK has been doing something similar for many
years. A proof of concept exercise was done by the CEGB in the 1970's
and was eventually revived and became normal practice in the early
1990's. They do it from a wheeled trolley though rather than crawling
along the line. The discharge you see in the video is completely
normal and it's just a case of equalising the charge. The line is
fully in service - which is precisely why it is done live, to save the
costs of constraining generation, and in the case of operations in the
UK could be carrying around 2000A per phase - or 500-1000A per
individual conductor

Spacer replacement (the H or X shaped bars between individual
conductors) on 2 and 4 conductor overhead 400 and 275kV lines is
routinely done live in the UK. Last time I saw them in person was
two or three years ago on the 400kV line that passes over the A55 near
Bangor in North Wales.




--

On Mon, 28 Jan 2008 13:28:02 +0000, The Natural Philosopher
wrote:

neverwas wrote:
snip
"There was or is a DC power cable across the north of the North Sea
beween Scotland and Norway????" Purpose of which to share power
between those two countries which have hydro generating capabilities.
Seem to remember reading about it in the mid 1950s.


No way.

ISTR the cross-channel link to France was the announced as the first
UK-Europe power sharing. And that seems to be confirmed by a quick
Google which brings up the history here with no mention of Scotland
until 2001 to NI
http://www2.theiet.org/oncomms/secto...53EE3D46B2112D


Yes. I visited it in the 60's and it was as far as I know the ONLY
external grid link in the UK at that time, and as far as I know still is.

If you visited in the 60's then you visited the old now defunct 160MW
link. The new one, rated at 2000MW only entered service in 1986.

There is also a link to the Isle of Man built about 6 years ago, one
under construction to the Netherlands for completion in 2010, and two
others planned to link to Ireland and Norway.


--

On Mon, 28 Jan 2008 19:56:13 +0000, The Natural Philosopher
wrote:

Yes, but those cables are NOT running at full AC.

Oh yes they are.

For a start there is no such thing as half AC and more to the point if
the lines were out of service then they would always be earthed at the
remote ends, with earths placed at the adjacent towers from the
conductors to the pylon structure / earthwire and the overhead line
worker would approach the conductor by climbing across the insulator
strings. In such circumstances you shouldn't ever see discharge and
you'd only wear normal clothing rather than a mesh suit.

So what you are seeing is not just pickup from an adjacent in service
line and in essence that is *exactly* how live line working on HV is
performed.


--

Matt wrote:
On Mon, 28 Jan 2008 13:28:02 +0000, The Natural Philosopher
wrote:

neverwas wrote:
snip
"There was or is a DC power cable across the north of the North Sea
beween Scotland and Norway????" Purpose of which to share power
between those two countries which have hydro generating capabilities.
Seem to remember reading about it in the mid 1950s.

No way.
ISTR the cross-channel link to France was the announced as the first
UK-Europe power sharing. And that seems to be confirmed by a quick
Google which brings up the history here with no mention of Scotland
until 2001 to NI
http://www2.theiet.org/oncomms/secto...53EE3D46B2112D


Yes. I visited it in the 60's and it was as far as I know the ONLY
external grid link in the UK at that time, and as far as I know still is.

If you visited in the 60's then you visited the old now defunct 160MW
link.

Yup. That was it!


The new one, rated at 2000MW only entered service in 1986.


2GW? I suppose solid state switches make it feasible.

There is also a link to the Isle of Man built about 6 years ago, one
under construction to the Netherlands for completion in 2010,

Found that one.

and two
others planned to link to Ireland and Norway.



Norway sounds unlikely..why there?

On Tue, 29 Jan 2008 12:01:34 +0000, The Natural Philosopher
wrote:

Norway sounds unlikely..why there?

Cheap hydro


--

Matt wrote:
On Tue, 29 Jan 2008 12:01:34 +0000, The Natural Philosopher
wrote:

Norway sounds unlikely..why there?

Cheap hydro


Fairy Nuff.

That probably stands on its own two feet then.

And the Finns are next door with their reactors...

In article , Matt
scribeth thus
On Mon, 28 Jan 2008 19:56:13 +0000, The Natural Philosopher
wrote:

Yes, but those cables are NOT running at full AC.

Oh yes they are.

For a start there is no such thing as half AC and more to the point if
the lines were out of service then they would always be earthed at the
remote ends, with earths placed at the adjacent towers from the

When they were rewiring the line for Wisbech to Stocking Pelham it
seemed they had earths on every pylon!...

conductors to the pylon structure / earthwire and the overhead line
worker would approach the conductor by climbing across the insulator
strings. In such circumstances you shouldn't ever see discharge and
you'd only wear normal clothing rather than a mesh suit.

So what you are seeing is not just pickup from an adjacent in service
line and in essence that is *exactly* how live line working on HV is
performed.



This is quite a good site on the subject...


http://members.tripod.com/~aberkers/work.html
--
Tony Sayer

On 2008-01-29 13:40:53 +0000, The Natural Philosopher said:

Matt wrote:
On Tue, 29 Jan 2008 12:01:34 +0000, The Natural Philosopher
wrote:

Norway sounds unlikely..why there?

Cheap hydro


Fairy Nuff.

That probably stands on its own two feet then.

And the Finns are next door with their reactors...

Next door but one unless you go a tortuous way round,

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Matt
saying something like:

http://www.glumbert.com/media/highpower

mark


Nothing new there. The UK has been doing something similar for many
years. A proof of concept exercise was done by the CEGB in the 1970's
and was eventually revived and became normal practice in the early
1990's.

Earlier than that. I was told about this in 1970 by a physics lecturer
who was ex-industry. Subsequent to that, anytime I saw blokes crawling
or trollying around EHV cables I assumed they were doing it live in
their mesh suits.
--

Dave