Antenna suspended from helicopter causes power cut near Balmedie

[MB]

Not a broadcast antenna fortunately!

I saw some blurb about it yesterday and it did seem rather big.



Antenna suspended from helicopter causes power cut near Balmedie

https://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-62940240

[NY]

"MB" <M...@nospam.net> wrote in message news:tg55jt$7nid$1...@dont-email.me...

I'm surprised that it caused a power cut, as opposed to a brief power blip.
If the antenna shorted between two of the three phases on what looked like
11 or 33 kV overhead lines, would that be enough to permanently trip a
circuit breaker (or blow a fuse), as opposed to temporarily tripping a
breaker that would immediately try re-applying the power to see if the fault
has been transient?

[MB]

On 17/09/2022 21:37, NY wrote:
> I'm surprised that it caused a power cut, as opposed to a brief power blip.
> If the antenna shorted between two of the three phases on what looked like
> 11 or 33 kV overhead lines, would that be enough to permanently trip a
> circuit breaker (or blow a fuse), as opposed to temporarily tripping a
> breaker that would immediately try re-applying the power to see if the fault
> has been transient?

What if it dropped on the power line and remained there?

[tony sayer]

In article <tg5ftp$8k9j$1...@dont-email.me>, MB <M...@nospam.net> scribeth
thus

Piss spoor bit of flying but if it was looking for minerals in the
ground perhaps it needs to fly low!.

Could have been very nasty for the pilot:(
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

[Andy Burns]

NY wrote:

>> https://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-62940240
>
> I'm surprised that it caused a power cut, as opposed to a brief power blip.

The frame didn't seem to be anywhere near the pole where the main arc occurred,
then there were two smaller arcs down at ground level so maybe the cable fell to
the ground? The frame doesn't appear to have any dangly bits

<https://youtu.be/jmvSXZE4MeE>

[Brian Gaff]

So how come there was somebody there videoing it at the time?

Not that you would know what was going on from the soundtrack, it just
sounds like a helicopter and wind noise.
Brian

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"MB" <M...@nospam.net> wrote in message news:tg55jt$7nid$1...@dont-email.me...

[Brian Gaff]

Leaves on trees are a big danger for helicopters, if a branch has broken a
bit and is swinging about it can bring a chopper down with a bump. That is
as I understand it what happened to a chopper being flown some years ago by
Mike Smith with a well known presenter on board as it landed. both injured.
I'm not sure I'd want to be in a helicopter a lot to be honest.

Brian

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"tony sayer" <to...@bancom.co.uk> wrote in message
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[Stephen Wolstenholme]

On Sun, 18 Sep 2022 16:43:49 +0100, "Brian Gaff"
<brian...@gmail.com> wrote:

>So how come there was somebody there videoing it at the time?
>
>Not that you would know what was going on from the soundtrack, it just
>sounds like a helicopter and wind noise.
> Brian

It looks like a amateur smartphone video. It was obviously being held
in portrait rather than landscape.

Steve

[Liz Tuddenham]

fNY <m...@privacy.invalid> wrote:

[...]

> If the antenna shorted between two of the three phases on what looked like
> 11 or 33 kV overhead lines, would that be enough to permanently trip a
> circuit breaker (or blow a fuse), as opposed to temporarily tripping a
> breaker that would immediately try re-applying the power to see if the fault
> has been transient?

I don't think most 11kV lines are equipped with re-closing breakers and
I doubt if 33kV ones are either..


--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

[NY]

On 18/09/2022 18:35, Liz Tuddenham wrote:
> fNY <m...@privacy.invalid> wrote:
>
> [...]
>> If the antenna shorted between two of the three phases on what looked like
>> 11 or 33 kV overhead lines, would that be enough to permanently trip a
>> circuit breaker (or blow a fuse), as opposed to temporarily tripping a
>> breaker that would immediately try re-applying the power to see if the fault
>> has been transient?
>
> I don't think most 11kV lines are equipped with re-closing breakers and
> I doubt if 33kV ones are either..

OK, so if our village gets short 1-second power blips especially in wet
and/or windy weather, what is causing the power to be restored after it
goes off - probably due to overhanging trees touching the wires?

Would it be due to shorts on the 240 V overhead lines between the
substation and the houses, rather than on the 11/33 kV overhead lines
that feed the substation? Do substations have reclosing breakers?

I'm sure when the engineer from Northern Powergen came round, he said
that a) he could see branches touching the high voltage lines, and b)
that the breakers would retry a few times.

I remember one night the power was off and on every few seconds, almost
exclusively for short < 5 second breaks, over a period of about an hour.
That sounds like something somewhere is retrying and is not even giving
up after a few failures.

[NY]

My impression from watching the video is that the frame looks to get
very close to the top of one of the poles, jerks away, and then there is
a bright light at the top of the pole followed by a smaller one on the
ground.

[NY]

On 18/09/2022 16:43, Brian Gaff wrote:
> So how come there was somebody there videoing it at the time?

I would imagine the sight of a helicopter dangling a huge rectangular
frame below it, which looked to be about twice as long as the
helicopter, was sufficiently unusual for someone to video it - and they
happened to capture the arcing at the top of the pole and on the ground
as the frame *apparently* touched the cables and shorted them and/or
caused them to fall to the ground.

[NY]

Watching it with a full-screen browser, the pole appears to be bent
sideways to the right (at 00:03 in the video) as the frame touches the
top of the pole, which may have snapped one of the wires or caused two
wires to touch. I get the impression that the frame itself didn't cause
the short via the frame; it was the sudden tilting of the pole that
caused it.

The pilot cocked up there. Part of the problem was that he was too low,
and part was that the frame was tipping instead of remaining parallel to
the ground, so even if the average height of the frame was (just) OK,
one end probably dipped low enough to touch the pole. It must have given
it one hell of a wallop to make the pole move, when they are designed to
withstand very strong winds.

[Brian Gaff]

Its quite hard to hold a phone in portrait mode with one hand though. I
wonder why there are not cameras that can work either way without re
orientating the phone?

Brian

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"Stephen Wolstenholme" <st...@easynn.com> wrote in message
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[Brian Gaff]

Yes that does sound a little careless. I'd have expected them to keep clear
of such wires as being a magnetic field sensing device, it must be somewhat
affected by the power lines. Perhaps nobody realised this.

Brian

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"NY" <m...@privacy.net> wrote in message
news:n_ScnQgoQe-bNrr-...@brightview.co.uk...

[MB]

On 19/09/2022 08:27, Brian Gaff wrote:
> Its quite hard to hold a phone in portrait mode with one hand though. I
> wonder why there are not cameras that can work either way without re
> orientating the phone?

If it is hard to hold in portrait mode, why are so many mobile phone
pictures taken in portrait mode when usually landscape is more suitable
for the subject.

[Liz Tuddenham]

NY <m...@privacy.net> wrote:

> On 18/09/2022 18:35, Liz Tuddenham wrote:
> > fNY <m...@privacy.invalid> wrote:
> >
> > [...]
> >> If the antenna shorted between two of the three phases on what looked like
> >> 11 or 33 kV overhead lines, would that be enough to permanently trip a
> >> circuit breaker (or blow a fuse), as opposed to temporarily tripping a
> >> breaker that would immediately try re-applying the power to see if the
> >> fault has been transient?
> >
> > I don't think most 11kV lines are equipped with re-closing breakers and
> > I doubt if 33kV ones are either..
>
> OK, so if our village gets short 1-second power blips especially in wet
> and/or windy weather, what is causing the power to be restored after it
> goes off - probably due to overhanging trees touching the wires?
>
> Would it be due to shorts on the 240 V overhead lines between the
> substation and the houses, rather than on the 11/33 kV overhead lines
> that feed the substation? Do substations have reclosing breakers?

Local 11/33kV > 240/440V substations didn't usually have them, perhaps
it is a recent thing. They used to be expensive and would have been
reserved for situations where they were absolutely necessary; perhaps
they have now dropped in price so that they can be fitted in local
substations and have become a cheap way to reduce the number of
unnecessary call-outs.

If an overhead wire could be shorted by overhanging trees, it would only
be a 240/440 volt circuit. The 11/33kV lines are regularly inspected
and any nearby trees cut back promptly. In extreme gales, the spans
between pylons on National Grid routes have been known to swing so much
they flash across, but 11/33kV spans don't seem prone to that.

> I'm sure when the engineer from Northern Powergen came round, he said
> that a) he could see branches touching the high voltage lines, and b)
> that the breakers would retry a few times.

Perhaps their inspection and maintenance schedules have been cut back,
but in the South-West they are quite pro-active about removing tree
growth from 11/33kV lines long before it could become a problem.

> I remember one night the power was off and on every few seconds, almost
> exclusively for short < 5 second breaks, over a period of about an hour.
> That sounds like something somewhere is retrying and is not even giving
> up after a few failures.

It does sound like a recloser at work (but I would not have thought it
would keep re-trying fo a whole hour, they normally operate three times
and then give up). Perhaps there is one for a whole district or a whole
network, but I think fuses (combined with isolaters on the tops of
poles) are the norm for the local 11kV overhead distribution networks.
Was the main breaker so fast that it tripped before the local fuses
could blow? Perhaps you are so near the substation that there isn't a
fuse in your branch?

Could the on/off pattern have been caused by an open circuit due to a
bad connection that was disturbed by wind or tree movement (or even
thermal cycling)? An intermittent short circuit would be reported and
traced quickly because it would light up the sky, but an open circuit
would only be reported when its nuisance effect became intolerable.

[Liz Tuddenham]

Brian Gaff <brian...@gmail.com> wrote:

> Yes that does sound a little careless. I'd have expected them to keep clear
> of such wires as being a magnetic field sensing device, it must be somewhat
> affected by the power lines. Perhaps nobody realised this.

The magnetic field from high-voltage power lines is not very strong and
falls away rapidly with distance. because the currents in the conductors
are balanced and their fields have a sum of zero.

People who panic about living near power lines are exposed to a much
greater magnetic field from their fish tank pump or electric blanket
(and the electric fields can be stopped by a piece of wet paper or the
walls of a house).

[Andy Burns]

NY wrote:

> Andy Burns wrote:
>
>> <https://youtu.be/jmvSXZE4MeE>
>
> My impression from watching the video is that the frame looks to get very close
> to the top of one of the poles, jerks away, and then there is a bright light at
> the top of the pole followed by a smaller one on the ground.

Looking again, the frame is bigger (relative to the poles) than I thought and
hence not so far in front of them as I'd thought.

The cross-bar at the top of the pole was hit causing it to bounce back and forth
a couple of times, then the arc happened, presumably the cables broke and fell
causing the second arc on the ground, the third flash happened a long way to the
left near the end of the clip ... maybe it was just a reflection from something
shiny, or maybe it was even someone signalling with a torch?

[Andy Burns]

NY wrote:

> Watching it with a full-screen browser

The BBC seem to have "dicked about" with the video resolution, unlike the Press
& Journal, who shoved it behind a paywall, this is better when viewed full-screen.

<https://content.jwplatform.com/previews/vOeBsoFw>

[Andy Burns]

Liz Tuddenham wrote:

> The magnetic field from high-voltage power lines is not very strong and
> falls away rapidly with distance.

Given the helicopter survey claims to be able to detect minerals 500m
underground, is it likely to be pumping-out much power?

[Liz Tuddenham]

Which 'it' are you referring to?

Neither power lines nor helicopters are designed to emit power (they try
to conserve it for their intended purposes). A geomagnetic device might
be intermittently pulsing large bursts of power of very short duration
(so the average power is actually quite low), but the detection system
would presumably be designed to receive only those pulses. It would
have to reject fields from power lines, helicopter electrics, etc.
otherwise it wouldn't work very well.

[MB]

On 19/09/2022 11:58, Andy Burns wrote:
> The BBC seem to have "dicked about" with the video resolution, unlike the Press
> & Journal, who shoved it behind a paywall, this is better when viewed full-screen.

I presume the "thing" has some weight to it?

There have been a number of accidents with helicopters carrying bags of
<something> to drop on forested areas. They have made the mistake of
flying back for with nothing on their hook which has swung upwards into
the rotors.

I can't see that being the case here but it can be a problem when
carrying loads below helicopters.

[NY]

"Liz Tuddenham" <l...@poppyrecords.invalid.invalid> wrote in message
news:1pyivd2.1taxvcw1cm8mpwN%

> If an overhead wire could be shorted by overhanging trees, it would only
> be a 240/440 volt circuit. The 11/33kV lines are regularly inspected
> and any nearby trees cut back promptly. In extreme gales, the spans
> between pylons on National Grid routes have been known to swing so much
> they flash across, but 11/33kV spans don't seem prone to that.

I have definitely seen trees which are taller than 11/33 kV wires (three
wires arranged *horizontally* on a head that is supported by a wooden pole
or pair of poles) that run close to the trees. If those trees were not kept
pruned, shorting would be possible after a lot of summer growth.

When our village had all the problems with recurring 1-second power cuts
towards the end of each summer, and I kicked up a stink with Northern
Powergrid, the engineer who came out to investigate went away to survey the
line and reported back to me that the fault *was* in a 33 kV line, which is
why it was taking out the whole village rather than just the streets which
were fed by overheard 240 V.

We had a couple of power cuts today - one was a 1-second blip, the other was
about 90 seconds. I wonder whether that was overhanging trees again, or
whether it was exceptional load of everybody having their TV on to watch the
Queen's funeral. I may need to phone Northern Powergrid tomorrow to remind
them to check for overhanging trees in the area.

The fact that most of our powercuts are brief suggests that somewhere
(whether 11/33 kV or 240 V) there are reclosing breakers.


Are the cables of 132 and 400 kV pylons theoretically able to swing together
and touch, or is the amount of slack designed to be small enough that two
cables that swing in opposite directions can never touch? I suppose the
problem is worst in hot weather when the wires will expand more in the heat.

[Liz Tuddenham]

NY <m...@privacy.invalid> wrote:

[...]

> I have definitely seen trees which are taller than 11/33 kV wires (three
> wires arranged *horizontally* on a head that is supported by a wooden pole
> or pair of poles) that run close to the trees. If those trees were not kept
> pruned, shorting would be possible after a lot of summer growth.

It sounds as though the electricity distributors in your area are a lot
less paranoid about trees than they are in mine.

The insulators give you a good clue about the line voltage, there are
usually one per phase for 11kV and three per phase (or one much taller
one) for 33kV. Just because a line is insulated to 33kV doesn't
necessarily mean it is running at 33kV; it might just be 'future
proofed' or useable as a reserve in the event of maintenance or
breakdown taking out the normal 33kV feeder.

> The fact that most of our powercuts are brief suggests that somewhere
> (whether 11/33 kV or 240 V) there are reclosing breakers.

It does, but the lax attitude of your suppliers comes as a surprise to
me.

> Are the cables of 132 and 400 kV pylons theoretically able to swing together
> and touch, or is the amount of slack designed to be small enough that two
> cables that swing in opposite directions can never touch? I suppose the
> problem is worst in hot weather when the wires will expand more in the heat.

My sister used to live within sight of a major 132kV line. She told me
of an evening of spectacular 'fireworks' displays (accompanied by
widespread power cuts) during an exceptionally windy storm. The cables
may not have touched, but they could have come near enough to start an
arc. I don't remember what the temperature was at the time.

[MB]

On 19/09/2022 22:52, Liz Tuddenham wrote:
> It sounds as though the electricity distributors in your area are a lot
> less paranoid about trees than they are in mine.

You often see them doing them doing power line inspections by helicopter.

Someone I knew got fed up with interference on the radio, so went out
with a portable radio and found an insulator that was arcing over.

He notified Hydro Electric and they were quite grateful.

[tony sayer]

In article <1pyjw4b.5cf1pr1qjo5fdN%l...@poppyrecords.invalid.invalid>,
Liz Tuddenham <l...@poppyrecords.invalid.invalid> scribeth thus

>NY <m...@privacy.invalid> wrote:
>
>[...]
>> I have definitely seen trees which are taller than 11/33 kV wires (three
>> wires arranged *horizontally* on a head that is supported by a wooden pole
>> or pair of poles) that run close to the trees. If those trees were not kept
>> pruned, shorting would be possible after a lot of summer growth.
>
>It sounds as though the electricity distributors in your area are a lot
>less paranoid about trees than they are in mine.
>
>The insulators give you a good clue about the line voltage, there are
>usually one per phase for 11kV and three per phase (or one much taller
>one) for 33kV. Just because a line is insulated to 33kV doesn't
>necessarily mean it is running at 33kV; it might just be 'future
>proofed' or useable as a reserve in the event of maintenance or
>breakdown taking out the normal 33kV feeder.
>

You can have usually single phase i.e. 2 wire 11 kV or three wire phase
11 kV

Never seen any single phase 33 kV around here there are 66 kV lines and
an odd 132 system thats pole mounted unlike the pylon arrangement.

>
>> The fact that most of our powercuts are brief suggests that somewhere
>> (whether 11/33 kV or 240 V) there are reclosing breakers.
>

Got them on some 11 overheads here..

This is a maybe 33 single bit i think its a 132 line with regard to the
insulator size?.

https://goo.gl/maps/zbGragZJDjMFD83x5

>It does, but the lax attitude of your suppliers comes as a surprise to
>me.
>
>> Are the cables of 132 and 400 kV pylons theoretically able to swing together
>> and touch, or is the amount of slack designed to be small enough that two
>> cables that swing in opposite directions can never touch? I suppose the
>> problem is worst in hot weather when the wires will expand more in the heat.
>
>My sister used to live within sight of a major 132kV line. She told me
>of an evening of spectacular 'fireworks' displays (accompanied by
>widespread power cuts) during an exceptionally windy storm. The cables
>may not have touched, but they could have come near enough to start an
>arc. I don't remember what the temperature was at the time.
>

Know a little ditty re that!..

The National grid came to pass,
Its wires were made of Brass.
In windy weather they'd smash together,
And sparks would fly out of its arse!

[Graham.]

On Mon, 19 Sep 2022 11:44:54 +0100, Andy Burns <use...@andyburns.uk>
wrote:

Three month late to this but never mind.
The third flash was itself three flashes, the last one brighter than
the others. I have no doubt it was a person using a camera with the
flash set to anti red-eye mode.


Incidentally I found this

https://aberdeenminerals.com/projects/airborne-geophysics/


Oh and this!
https://www.legislation.gov.uk/uksi/2016/672/pdfs/uksi_20160672_en.pdf

--
Graham.
%Profound_observation%