On 29/07/14 11:13, newshound wrote:
On 28/07/2014 13:29, John Williamson wrote:
On 28/07/2014 08:23, harryagain wrote:


Where exactly is this arc drawn for 30 minutes and for what purpose.?


The arc *can* be drawn by using the DC charge stored in the cable. No
claim was made that it ever had been drawn either deliberately or
otherwise, though it's the kind of trick that installation engineers
have been known to pull as a joke, or that happens when things go wrong
when commissioning plant of this sort.


If you watch footage of repairs to 400 kV overhead lines (typically shot
from helicopters) you will see long and impressive arcs being drawn from
these for several seconds while they are brought down to earth potential.

No - that's not what they are doing. Those lines are live.

What they are doing is making an equipotential bond between the line and
helicopter. The helicopter as basically a conducting object in free air
has inherent capacitance to ground and the the reactance is sufficient
to cause a not insignificant current to flow at 1/2 mil volts 50-60Hz

If the line were made dead, it would have been earth strapped at both
ends before anyone was let near it (standard operating procedure).

On 29/07/14 11:36, Tim Watts wrote:
On 29/07/14 11:13, newshound wrote:
On 28/07/2014 13:29, John Williamson wrote:
On 28/07/2014 08:23, harryagain wrote:


Where exactly is this arc drawn for 30 minutes and for what purpose.?


The arc *can* be drawn by using the DC charge stored in the cable. No
claim was made that it ever had been drawn either deliberately or
otherwise, though it's the kind of trick that installation engineers
have been known to pull as a joke, or that happens when things go wrong
when commissioning plant of this sort.


If you watch footage of repairs to 400 kV overhead lines (typically shot
from helicopters) you will see long and impressive arcs being drawn from
these for several seconds while they are brought down to earth potential.

No - that's not what they are doing. Those lines are live.

What they are doing is making an equipotential bond between the line and
helicopter. The helicopter as basically a conducting object in free air
has inherent capacitance to ground and the the reactance is sufficient
to cause a not insignificant current to flow at 1/2 mil volts 50-60Hz

If the line were made dead, it would have been earth strapped at both
ends before anyone was let near it (standard operating procedure).

And for a quicky dodgey calcL

Capacitance of sphere of radius 1m (tiny helicopter) in free space is
about 0.1nF

Reactance at 60Hz approx:

1 / (2f x pi x C) = 27MOhms

Current at 254kV to earth (440kV phase-phase, for 3 phase) = V/R
= about 10mA

Which is enough to hurt and be a danger.


In reality I think the presence of a nearby ground plane (the ground)
plus the fact the helicopter is longer than 2m and has lots of sticky
out bits is likely to push the current a fair bit higher.

Plus some of those lines you speak of may be higher than 440kV.

So on that basis, whilst a small bird can sit on an HV line, if an
ostrich got up there, its feet would probably tingle

On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,

common to all areas, what would, or could, it be? Still AC? 300 volts?

Different frequency?





David Paste.

All other things being equal, the only reason for not having widespread electricity distribution in 2014 would be if the filament lamp had never been invented, which was the original 'killer app' to make public electricity supply a viable business. The problem before that was "sub-dividing the electric light", as in the 19th century, before filament lamps were invented, only arc lamps were available, and these were only practical for large outputs, so tended to be used with local generators at about 100v DC, 70v being needed to maintain an arc in air, the rest for the regulating resistance to limit the current.

Eventually discharge lamps (mercury, sodium, etc) would be developed, but not in domestic sizes, these are more efficient on AC supplies, allowing the use of transformer ballasts, so things would have panned out at 440v 50Hz three-phase, for induction motors in industry, stepping down to 110v single-phase for power tools and discharge lighting, supplied by local generation from natural gas or diesel engines.

In the UK and other countries with natural gas supplies, domestic lighting would be by gas mantles, with no general distribution of electricity, instead household thermo-electric generators could be used for powering electronic equipment at 50v DC, so avoiding the need for shock protection measures, and gas for everything else, with LPG cartridges for portable appliances such as irons, places that did not have gas supplies could use kerosene or LPG cylinders.

On 29/07/2014 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
....
The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

Are you suggesting that Harry might have posted an article he has not
read thoroughly and understood completely?

--
Colin Bignell

On 29/07/2014 11:24, newshound wrote:
On 28/07/2014 10:39, Robin wrote:
That is the number of deaths and serious injuries in the UK every
year. Around 2.5 million people in the UK also receive a mains voltage
electric shock every year.

Figures from an Electrical Safety Council surveys which have long left
me a bit puzzled. As regards the 2.5m electric shocks, family etc I've
asked (who include people in work and retired, people with young
children, people in rented accommodation etc) don't seem to get shocks
at that rate. So I wonder who/where they are. And as regards "serious
in jury", they define that to include "severe pain" (and all whether or
not medical treatment required).


Once in 20 years among the adult population does not seem wildly out to
me. Especially if you include "tingles" from wet appliances, and even
more static shocks to those who cannot differentiate. But I do wonder
where the statistic comes from.

Probably they got somebody like Mori to carry out a poll, asking a
number of statistically average people and extrapolating from that.

--
Colin Bignell

On 29/07/2014 15:38, Nightjar "cpb"@ insert my surname here wrote:
On 29/07/2014 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
...
The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

Are you suggesting that Harry might have posted an article he has not
read thoroughly and understood completely?

Looks innocent Would I do such a thing? (1)

--
Tciao for Now!

John.

(1) Yes.

On 29/07/14 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 28/07/14 08:22, John Williamson wrote:
On 28/07/2014 02:03, The Natural Philosopher wrote:
On 27/07/14 22:45, tony sayer wrote:
In article ,
scribeth thus
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself, other
than cooling effects.

jgh

Inductive and Capactive losses theres some stuff on the AAB website
somewhere;!...

Not sure that induction plays any part..

Transmission lines have a calculable inductance per metre, and as the
length approaches infinity, so does that inductance.

There is a characteristic impedance for transmission lines, which
affects both transmission and losses.


So, having taught grandmother to suck eggs, where is the power loss
due
to
inductance?

The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

And in fact establishing a magnetic filed takes energy, but reversing it
you get the energy back.

That's how transformers work.


--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

On 29/07/2014 16:15, The Natural Philosopher wrote:
On 29/07/14 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 28/07/14 08:22, John Williamson wrote:
On 28/07/2014 02:03, The Natural Philosopher wrote:
On 27/07/14 22:45, tony sayer wrote:
In article
,
scribeth thus
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself, other
than cooling effects.

jgh

Inductive and Capactive losses theres some stuff on the AAB
website
somewhere;!...

Not sure that induction plays any part..

Transmission lines have a calculable inductance per metre, and as
the
length approaches infinity, so does that inductance.

There is a characteristic impedance for transmission lines, which
affects both transmission and losses.


So, having taught grandmother to suck eggs, where is the power loss
due
to
inductance?

The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

And in fact establishing a magnetic filed takes energy, but reversing it
you get the energy back.

That's how transformers work.


You get *all* the energy back, less the hysteresis losses in the iron
core. There are no such losses in the copper windings, and air cored
transformers don't suffer them either, they're just not very practical
at 50Hz or so due to the size they'd have to be.

To get back to the original consideration of copper or aluminium
transmission lines, there are no hysteresis losses in the line. You will
get some if the lines are made of ferrous metals, though, but the
hysteresis losses would be swamped by the resistive ones.

--
Tciao for Now!

John.

On 29/07/14 16:51, John Williamson wrote:
You get *all* the energy back, less the hysteresis losses in the iron
core. There are no such losses in the copper windings, and air cored
transformers don't suffer them either, they're just not very practical
at 50Hz or so due to the size they'd have to be.

And because they'd be so enormous, there'd probably be losses in
anything for some distance in the form of eddy currents

No - that's not what they are doing. Those lines are live.

What they are doing is making an equipotential bond between the line and
helicopter. The helicopter as basically a conducting object in free air
has inherent capacitance to ground and the the reactance is sufficient
to cause a not insignificant current to flow at 1/2 mil volts 50-60Hz

If the line were made dead, it would have been earth strapped at both
ends before anyone was let near it (standard operating procedure).

And for a quicky dodgey calcL

Capacitance of sphere of radius 1m (tiny helicopter) in free space is
about 0.1nF

Reactance at 60Hz approx:

1 / (2f x pi x C) = 27MOhms

Current at 254kV to earth (440kV phase-phase, for 3 phase) = V/R
= about 10mA

Which is enough to hurt and be a danger.


In reality I think the presence of a nearby ground plane (the ground)
plus the fact the helicopter is longer than 2m and has lots of sticky
out bits is likely to push the current a fair bit higher.

Plus some of those lines you speak of may be higher than 440kV.

So on that basis, whilst a small bird can sit on an HV line, if an
ostrich got up there, its feet would probably tingle


Now cometh a debate re can an ostriches sit on a power line;!()(

What lines are higher then the 400 kV grid then?..


--
Tony Sayer

On 29/07/14 16:51, John Williamson wrote:
To get back to the original consideration of copper or aluminium
transmission lines, there are no hysteresis losses in the line. You will
get some if the lines are made of ferrous metals, though, but the
hysteresis losses would be swamped by the resistive ones.

Yep.

Mind you the AL ones are wound on steel cores.

But the resistive losses dominate. Massively.

Because the flux density on a single wire at a few hundred amps only is
very very low.




--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

harryagain wrote:

Our main link to Europe is not underwater, it is via the channel tunnel.

The channel tunnel, that well known airborn structure, eh?

--
Scott

Where are we going and why am I in this handbasket?

On Tue, 29 Jul 2014 11:54:17 +0100, Tim Watts
wrote:


In reality I think the presence of a nearby ground plane (the ground)
plus the fact the helicopter is longer than 2m and has lots of sticky
out bits is likely to push the current a fair bit higher.

Plus some of those lines you speak of may be higher than 440kV.

So on that basis, whilst a small bird can sit on an HV line, if an
ostrich got up there, its feet would probably tingle

See plenty of birds on 11kV and 33kV lines but I don't think I have
ever seen any on the higher voltages. I suppose they must sense the
electrical field as they get close.

G.Harman

wrote:

See plenty of birds on 11kV and 33kV lines but I don't think I have
ever seen any on the higher voltages. I suppose they must sense the
electrical field as they get close.

Apparently ravens and storks like them ...

http://www.copperconsultancy.com/pylons-become-raven-havens

On 29/07/2014 11:36, Tim Watts wrote:
On 29/07/14 11:13, newshound wrote:
On 28/07/2014 13:29, John Williamson wrote:
On 28/07/2014 08:23, harryagain wrote:


Where exactly is this arc drawn for 30 minutes and for what purpose.?


The arc *can* be drawn by using the DC charge stored in the cable. No
claim was made that it ever had been drawn either deliberately or
otherwise, though it's the kind of trick that installation engineers
have been known to pull as a joke, or that happens when things go wrong
when commissioning plant of this sort.


If you watch footage of repairs to 400 kV overhead lines (typically shot
from helicopters) you will see long and impressive arcs being drawn from
these for several seconds while they are brought down to earth potential.

No - that's not what they are doing. Those lines are live.

What they are doing is making an equipotential bond between the line and
helicopter. The helicopter as basically a conducting object in free air
has inherent capacitance to ground and the the reactance is sufficient
to cause a not insignificant current to flow at 1/2 mil volts 50-60Hz

If your thinking of the bit of video footage I am thinking of, then I
have a suspicion that may have been a DC HV line anyway.

If the line were made dead, it would have been earth strapped at both
ends before anyone was let near it (standard operating procedure).

Indeed.

--
Cheers,

John.

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

On 29/07/2014 15:40, Nightjar "cpb"@ insert my surname here wrote:
On 29/07/2014 11:24, newshound wrote:
On 28/07/2014 10:39, Robin wrote:
That is the number of deaths and serious injuries in the UK every
year. Around 2.5 million people in the UK also receive a mains voltage
electric shock every year.

Figures from an Electrical Safety Council surveys which have long left
me a bit puzzled. As regards the 2.5m electric shocks, family etc I've
asked (who include people in work and retired, people with young
children, people in rented accommodation etc) don't seem to get shocks
at that rate. So I wonder who/where they are. And as regards "serious
in jury", they define that to include "severe pain" (and all whether or
not medical treatment required).


Once in 20 years among the adult population does not seem wildly out to
me. Especially if you include "tingles" from wet appliances, and even
more static shocks to those who cannot differentiate. But I do wonder
where the statistic comes from.

Probably they got somebody like Mori to carry out a poll, asking a
number of statistically average people and extrapolating from that.

Possibly a few stats from A&E departments as well...


--
Cheers,

John.

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

On 30/07/2014 03:25, John Rumm wrote:
On 29/07/2014 15:40, Nightjar "cpb"@ insert my surname here wrote:
On 29/07/2014 11:24, newshound wrote:
On 28/07/2014 10:39, Robin wrote:
That is the number of deaths and serious injuries in the UK every
year. Around 2.5 million people in the UK also receive a mains voltage
electric shock every year.

Figures from an Electrical Safety Council surveys which have long left
me a bit puzzled. As regards the 2.5m electric shocks, family etc
I've
asked (who include people in work and retired, people with young
children, people in rented accommodation etc) don't seem to get shocks
at that rate. So I wonder who/where they are. And as regards "serious
in jury", they define that to include "severe pain" (and all whether or
not medical treatment required).


Once in 20 years among the adult population does not seem wildly out to
me. Especially if you include "tingles" from wet appliances, and even
more static shocks to those who cannot differentiate. But I do wonder
where the statistic comes from.

Probably they got somebody like Mori to carry out a poll, asking a
number of statistically average people and extrapolating from that.

Possibly a few stats from A&E departments as well...


Most people who get a shock off the mains without any noticeable effect
won't end up in A&E.


--
Colin Bignell

Probably they got somebody like Mori to carry out a poll, asking a
number of statistically average people and extrapolating from that.

Yep. Details below[1][2] for the record + any other sceptical old gits
like me ;(

Possibly a few stats from A&E departments as well...

Not to arrive at a third of a million serious injuries.
Well the impact assessment in 2013 for the changes to Part P said A&E
figures must be treated with caution but the admissions due to electric
shock were less than 4,000 a year. That includes non-domestic. It also
reminded us that the original Part P assessment estimated "electrical
accidents caused around 41 fatalities, 2,740 serious injuries requiring
hospital treatment".

____________
[1]Shocks:
"4,032 interviews were conducted with adults in Great Britain aged 15+
from 06 to 27 May 2011 via Ipsos MORI's Capibus, the weekly face-to-face
omnibus survey, using a nationally representative quota sample across
Great Britain. The results have been weighted to reflect the known
profile of the adult population in Great Britain. Based on a confidence
interval of +/- 0.9% and the sample size of 4,032 the actual number
could vary between c2.1 to 2.8 million. Electric shock is defined as 'a
mains-voltage electric shock rather than a static shock of the type a
person might get from a car, for example."

[2]Injuries:
"Based on a survey of 4,032 adults in Great Britain aged 15+ who have
personally experienced an electric shock that resulted in injury while
at home or in the garden in the past twelve months including all those
who experienced one or more of the following injuries: Severe pain, Skin
burn without scarring, Bruising from a fall or severe muscular
contraction, Temporary blindness, Heartbeat disturbance, Persistent pain
or numbness, Higher blood pressure, Skin burn with scarring, Broken
bone(s), Difficulty breathing.'"


--
Robin
reply to address is (meant to be) valid

"John Williamson" wrote in message
...
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 28/07/14 08:22, John Williamson wrote:
On 28/07/2014 02:03, The Natural Philosopher wrote:
On 27/07/14 22:45, tony sayer wrote:
In article ,
scribeth thus
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself, other
than cooling effects.

jgh

Inductive and Capactive losses theres some stuff on the AAB website
somewhere;!...

Not sure that induction plays any part..

Transmission lines have a calculable inductance per metre, and as the
length approaches infinity, so does that inductance.

There is a characteristic impedance for transmission lines, which
affects both transmission and losses.


So, having taught grandmother to suck eggs, where is the power loss
due
to
inductance?

The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.


The energy lost is represented by the "S" shaped area on the graph.
Also known as "iron losses" in motors and transformers.
But even if there's no iron, energy is taken to establish/reverse the
magnetic field.

With DC it takes energy to establish a magnetic field but none to maintian
it (neglecting resitance losses)
You get the energy back on disconnection.

Car ignition coil is a case.

"The Natural Philosopher" wrote in message
...
On 29/07/14 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 28/07/14 08:22, John Williamson wrote:
On 28/07/2014 02:03, The Natural Philosopher wrote:
On 27/07/14 22:45, tony sayer wrote:
In article
,
scribeth thus
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself, other
than cooling effects.

jgh

Inductive and Capactive losses theres some stuff on the AAB
website
somewhere;!...

Not sure that induction plays any part..

Transmission lines have a calculable inductance per metre, and as
the
length approaches infinity, so does that inductance.

There is a characteristic impedance for transmission lines, which
affects both transmission and losses.


So, having taught grandmother to suck eggs, where is the power loss
due
to
inductance?

The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

And in fact establishing a magnetic filed takes energy, but reversing it
you get the energy back.

But not all of it.

That's how transformers work.

"John Williamson" wrote in message
...
On 29/07/2014 16:15, The Natural Philosopher wrote:
On 29/07/14 11:14, John Williamson wrote:
On 29/07/2014 07:43, harryagain wrote:
"John Williamson" wrote in message
...
On 28/07/2014 19:20, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 28/07/14 08:22, John Williamson wrote:
On 28/07/2014 02:03, The Natural Philosopher wrote:
On 27/07/14 22:45, tony sayer wrote:
In article
,
scribeth thus
Nightjar wrote:
AC for simple long-distance transmission...
Except for underwater cables, where it can cause unacceptable
transmission losses.

How does immersing a 11kV AC cable in water increase
transmission
losses? This isn't a joke question, I can't see how the medium
surrounding a cable changes the action of the cable itself,
other
than cooling effects.

jgh

Inductive and Capactive losses theres some stuff on the AAB
website
somewhere;!...

Not sure that induction plays any part..

Transmission lines have a calculable inductance per metre, and as
the
length approaches infinity, so does that inductance.

There is a characteristic impedance for transmission lines, which
affects both transmission and losses.


So, having taught grandmother to suck eggs, where is the power loss
due
to
inductance?

The loss arises from energy taken to reverse the magnetic field.
https://en.wikipedia.org/wiki/Magnetic_hysteresis


Not in copper or aluminium wires.

Any magnetic field takes energy to establish or reverse it.
Magnetic fields are associated with any electric current.


That's not what it says in the article you referred us to.

And in fact establishing a magnetic filed takes energy, but reversing it
you get the energy back.

That's how transformers work.


You get *all* the energy back, less the hysteresis losses in the iron
core. There are no such losses in the copper windings, and air cored
transformers don't suffer them either, they're just not very practical at
50Hz or so due to the size they'd have to be.

To get back to the original consideration of copper or aluminium
transmission lines, there are no hysteresis losses in the line. You will
get some if the lines are made of ferrous metals, though, but the
hysteresis losses would be swamped by the resistive ones.

The resistance losses vary with load.
Other losses are constant.

"Tim Watts" wrote in message
news
On 28/07/14 22:25, Andy Wade wrote:
On 28/07/2014 10:09, Tim Watts wrote:

I would say we might as well have 400V as 230V and more or less halve
the conductor sizes. Much more than that is getting silly though.

I'd vote for the standard domestic supply being 3x32 A (3-ph) instead of
1x100 A. Then we'd have the advantages of 3-phase for motors and
rectification, and could have 400 V appliances like cookers and showers
hooked-up with 2.5 or 4 mm^2 cables. Proposals now required for a
compact 5-pin 16 A plug & socket...


I agree...

If you look at a commando plug/socket, the pins are well built but not
that much heavier than a 15A round pin plug.

So I do not see why you could not make a 3 phase version of a 15A plug
that fitted in at least a double backbox.

They are already available.
https://en.wikipedia.org/wiki/Indust...gs_and_sockets

wrote in message
...
On Tuesday, July 29, 2014 8:37:56 AM UTC+1, The Natural Philosopher wrote:
On 29/07/14 08:27, wrote:
On Tuesday, July 29, 2014 7:53:51 AM UTC+1, harry wrote:
"Brian Gaff" wrote in message
...

Well the higher the frequency the more efficient transformers are,
and can
be smaller as witnessed by switch mode supplies.
I think for distribution reasons, the delivery would still be AC
though.
As a matter of interest, those who use the high voltage DC grids,
how do
they convert to AC when needed. have to be one large inverter!

No that's incorrect.
Higher frequency = smaller physical sized motors & transformers but
greater
losses.
Aircraft run on high frequency power to save weight.

HF smpsu transformers have much lower copper losses & total losses than
50Hz iron lumps.

Actually they don't.

They surely do. Why do you say they dont?

Iron losses are proportional to frequency.

"Jaffna Dog" wrote in message
...
On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,

common to all areas, what would, or could, it be? Still AC? 300 volts?

Different frequency?





David Paste.

All other things being equal, the only reason for not having widespread
electricity distribution in 2014 would be if the filament lamp had never
been invented, which was the original 'killer app' to make public
electricity supply a viable business. The problem before that was
"sub-dividing the electric light", as in the 19th century, before filament
lamps were invented, only arc lamps were available, and these were only
practical for large outputs, so tended to be used with local generators at
about 100v DC, 70v being needed to maintain an arc in air, the rest for the
regulating resistance to limit the current.

Eventually discharge lamps (mercury, sodium, etc) would be developed, but
not in domestic sizes, these are more efficient on AC supplies, allowing the
use of transformer ballasts, so things would have panned out at 440v 50Hz
three-phase, for induction motors in industry, stepping down to 110v
single-phase for power tools and discharge lighting, supplied by local
generation from natural gas or diesel engines.

In the UK and other countries with natural gas supplies, domestic lighting
would be by gas mantles, with no general distribution of electricity,
instead household thermo-electric generators could be used for powering
electronic equipment at 50v DC, so avoiding the need for shock protection
measures, and gas for everything else, with LPG cartridges for portable
appliances such as irons, places that did not have gas supplies could use
kerosene or LPG cylinders.


What drivel.

In the UK three hundred years ago the rich used beeswax candles
The poor used "dips", animal fat with rush wicks. Whale and seal oil was
also used.
Coal gas was invented here and became unversal for lighting. There were
initially no mantles, the gas was so impure, the flame was luminous.
Heating was by wood and then coal and coke, mostly open fires.
Gas fires were uncommon.
Most houses only had one room heated.

Electricity when it came was local, sometimes from local mines and
factories.
The national grid was first started in the 1920s.
There was AC, DC and a wide range of voltages.
Even in the 1960s light switches were DC capable and the voltages had only
just been made standard 240v.

Natural gas was only discovered in the 1960s and took some years to be
widely available.

On Mon, 28 Jul 2014 14:20:17 +0100, Tim Watts wrote:

On 28/07/14 12:30, The Other Mike wrote:

How do you phase lock the French grid to the Belgian Grid to the Dutch Grid to
the German one to the Swiss one etc etc. It doesn't in the main involve DC and
at AC it is no real problem.

Are they phased locked? I don't know.

If they are, then they have relatively long borders which means lots of
interconnections.

You aren't going to hold 2 disparate grids in sync with one or two cross
channel links - National Grid has enough trouble holding the UK grid in
phase between Scotland and the South (they have (or had at Bankside at
least) a phase indicator colloquially known as the "scottish wobblemeter".

If it started oscillating, a certain amount of panic ensued...

Presumably you mean the old National Control, close to Bankside but round the
corner in the concrete bunker of Sumner Street / Park Street. That is almost
ancient history, they moved to the 'new place' well outside London in 1996.
Essentially everything now on very large screen monitors and consolidated to
just one level of control (nothing remaining at regional level) and just an on
site local backup and a bloke on a phone when all else fails.

Not sure how national control would ever be aware of any real time phase state
as the data supplied to them from across the UK and also from Scotland is just
digitised Voltage and Current Transformer values with a local refresh rate in
the order of seconds to tens of seconds, the transfer protocol used does not
permit any element of time / data synchronisation between sites or against any
time standard for these digitised analogue values.

While it's clearly nowhere near ideal a 60GW UK grid could be kept in sync with
what is around a 600GW Euro network with 3GW of AC interconnects, it wouldn't do
anything else in normal circumstances, it's a bit of wire just like the rest of
the system and with a series reactor and appropriate generator governor response
it would remove any dumbell effect, but what happens during a fault in on or
around the interconnects and the recovery post fault is, as always, more of an
issue. It still has the potential to go tits up very fast. A DC interconnect
remains by far the best solution for the UK to Europe despite the complexity.

--

On Mon, 28 Jul 2014 22:25:43 +0100, Andy Wade
wrote:

On 28/07/2014 10:09, Tim Watts wrote:

I would say we might as well have 400V as 230V and more or less halve
the conductor sizes. Much more than that is getting silly though.

I'd vote for the standard domestic supply being 3x32 A (3-ph) instead of
1x100 A. Then we'd have the advantages of 3-phase for motors and
rectification, and could have 400 V appliances like cookers and showers
hooked-up with 2.5 or 4 mm^2 cables. Proposals now required for a
compact 5-pin 16 A plug & socket...

Just design a slightly enlarged version of one of these
http://en.wikipedia.org/wiki/DIN_connector


--

On Tue, 29 Jul 2014 18:08:53 +0100, tony sayer wrote:

What lines are higher then the 400 kV grid then?..

None in the UK, there will be an undersea / underground 600kV DC link in the
next couple of years down the West Coast. No perching ostriches allowed.
--

On Tue, 29 Jul 2014 18:42:53 +0100, The Natural Philosopher
wrote:

Mind you the AL ones are wound on steel cores.

Aluminium wound over steel is an older conductor design method commonly used for
supergrid installations until the late 1980's in the UK but these are often a
bottleneck on the network, so as they eventually succumb to corrosion and
internal failure they are not always being replaced like for like. During many
refurbs and upgrades they now use either an all aluminium design or aluminium
over a loose steel core (termed a gap conductor), with grease filling the gap
between the two.

There are developments in the pipeline for aluminium conductors over a composite
core, possible first large scale use in the UK would be on the route of the
upgraded 132kV to 400kV route for Hinkley Point C

--

On 30/07/2014 10:38, Tim Streater wrote:


The point of your post was *what*, precisely, harry?

He's finally discovered how to cut and paste?

His next great discovery will be the computer's "off" switch, with any luck.

(Hint: It's not the big red one round the back any more.)
--
Tciao for Now!

John.

On 29/07/14 18:08, tony sayer wrote:

Now cometh a debate re can an ostriches sit on a power line;!()(

What lines are higher then the 400 kV grid then?..



Foreign ones maybe - those helicopter youtube vids are not British AFAIK.

On 30/07/14 09:57, The Other Mike wrote:
On Tue, 29 Jul 2014 18:08:53 +0100, tony sayer wrote:

What lines are higher then the 400 kV grid then?..

None in the UK, there will be an undersea / underground 600kV DC link in the
next couple of years down the West Coast. No perching ostriches allowed.


DC of course would not be an issue on overhead lines.

There would be a small spark as some charge transferred to the
helicopter then that would be it - until it landed of course, then the
process would reverse.

On 29/07/14 20:47, wrote:
On Tue, 29 Jul 2014 11:54:17 +0100, Tim Watts
wrote:


In reality I think the presence of a nearby ground plane (the ground)
plus the fact the helicopter is longer than 2m and has lots of sticky
out bits is likely to push the current a fair bit higher.

Plus some of those lines you speak of may be higher than 440kV.

So on that basis, whilst a small bird can sit on an HV line, if an
ostrich got up there, its feet would probably tingle

See plenty of birds on 11kV and 33kV lines but I don't think I have
ever seen any on the higher voltages. I suppose they must sense the
electrical field as they get close.

G.Harman


Sounds likely...

Anyone who doubts the field strength, take a 4-6ft fluorescent tube and
hold it upright whilst standing under a grid line set, in the dark.

Perhaps not recommended, but Tomorrow's World did it and the tube does
glow - there's that many V/m

On 30/07/14 03:25, John Rumm wrote:

Possibly a few stats from A&E departments as well...

I slipped on some damp grass on a slope cutting the lawn last night. The
humidity was high and the dew arrived early - I thought the grass was
dry and wore inappropriate shoes (DMs with no tread left!).

So off I went to A&E this morning to check I had not broken my ankle (it
is possible to break an ankle and think its a bad sprain).

Fortunately not, so here I lie with my foot and a cushion and an ice
pack down my sock hoping it will not bugger up my holiday in 2 weeks!



So that probably went down as "lawnmower accident".

So when DIY lawn mowing is banned next year, blame me!

On 30/07/14 09:47, The Other Mike wrote:
On Mon, 28 Jul 2014 14:20:17 +0100, Tim Watts wrote:

On 28/07/14 12:30, The Other Mike wrote:

How do you phase lock the French grid to the Belgian Grid to the Dutch Grid to
the German one to the Swiss one etc etc. It doesn't in the main involve DC and
at AC it is no real problem.

Are they phased locked? I don't know.

If they are, then they have relatively long borders which means lots of
interconnections.

You aren't going to hold 2 disparate grids in sync with one or two cross
channel links - National Grid has enough trouble holding the UK grid in
phase between Scotland and the South (they have (or had at Bankside at
least) a phase indicator colloquially known as the "scottish wobblemeter".

If it started oscillating, a certain amount of panic ensued...

Presumably you mean the old National Control, close to Bankside but round the
corner in the concrete bunker of Sumner Street / Park Street.

Yes - my mate worked there - still works at Nat Grid control.

That is almost
ancient history, they moved to the 'new place' well outside London in 1996.
Essentially everything now on very large screen monitors and consolidated to
just one level of control (nothing remaining at regional level) and just an on
site local backup and a bloke on a phone when all else fails.

Not sure how national control would ever be aware of any real time phase state
as the data supplied to them from across the UK and also from Scotland is just
digitised Voltage and Current Transformer values with a local refresh rate in
the order of seconds to tens of seconds, the transfer protocol used does not
permit any element of time / data synchronisation between sites or against any
time standard for these digitised analogue values.

I did wonder that. I guess there must have been a dedicated set of
sensors just for that?

I heard about it as it went loopy and started wobbling (1995 ish)
causing some concern on the control desk, until my mate found out it was
a dodgy photocopier upsetting the local instrument.

The rest of the time he seemed to spend fixing the Dinowig instructor panel.

While it's clearly nowhere near ideal a 60GW UK grid could be kept in sync with
what is around a 600GW Euro network with 3GW of AC interconnects, it wouldn't do
anything else in normal circumstances, it's a bit of wire just like the rest of
the system and with a series reactor and appropriate generator governor response
it would remove any dumbell effect, but what happens during a fault in on or
around the interconnects and the recovery post fault is, as always, more of an
issue. It still has the potential to go tits up very fast. A DC interconnect
remains by far the best solution for the UK to Europe despite the complexity.

On Wednesday, July 30, 2014 8:30:53 AM UTC+1, Robin wrote:

Probably they got somebody like Mori to carry out a poll, asking a
number of statistically average people and extrapolating from that.

Yep. Details below[1][2] for the record + any other sceptical old gits
like me ;(
Possibly a few stats from A&E departments as well...
Not to arrive at a third of a million serious injuries.
Well the impact assessment in 2013 for the changes to Part P said A&E
figures must be treated with caution but the admissions due to electric
shock were less than 4,000 a year. That includes non-domestic. It also
reminded us that the original Part P assessment estimated "electrical
accidents caused around 41 fatalities, 2,740 serious injuries requiring
hospital treatment".
____________
[1]Shocks:
"4,032 interviews were conducted with adults in Great Britain aged 15+
from 06 to 27 May 2011 via Ipsos MORI's Capibus, the weekly face-to-face
omnibus survey, using a nationally representative quota sample across
Great Britain. The results have been weighted to reflect the known
profile of the adult population in Great Britain. Based on a confidence
interval of +/- 0.9% and the sample size of 4,032 the actual number
could vary between c2.1 to 2.8 million. Electric shock is defined as 'a
mains-voltage electric shock rather than a static shock of the type a
person might get from a car, for example."
[2]Injuries:
"Based on a survey of 4,032 adults in Great Britain aged 15+ who have
personally experienced an electric shock that resulted in injury while
at home or in the garden in the past twelve months including all those
who experienced one or more of the following injuries: Severe pain, Skin
burn without scarring, Bruising from a fall or severe muscular
contraction, Temporary blindness, Heartbeat disturbance, Persistent pain
or numbness, Higher blood pressure, Skin burn with scarring, Broken
bone(s), Difficulty breathing.'"

So injuries include 'bruising.' Let me guess, the survey was during work hours, when half the people asked were mentally ill. Surprisingly enough 50% of them were so bored that they said yes if asked if any scenario happened to them.


NT

"Tim Streater" wrote in message
.. .
In article , harryagain
wrote:

"Jaffna Dog" wrote in message
...
On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,
common to all areas, what would, or could, it be? Still AC? 300 volts?
Different frequency?

[blank lines and other cockups caused by Mr. Paste using google groups,
fixed]

[long and irrelevant post by harry, deleted]

The point of your post was *what*, precisely, harry?

Some (obviously foreign) retard was drivelling on some crap about the
history of domestic energy in the UK

On 30/07/2014 12:15, Tim Streater wrote:
In article , Tim Watts
wrote:

On 30/07/14 03:25, John Rumm wrote:

Possibly a few stats from A&E departments as well...

I slipped on some damp grass on a slope cutting the lawn last night.
The humidity was high and the dew arrived early - I thought the grass
was dry and wore inappropriate shoes (DMs with no tread left!).

So off I went to A&E this morning to check I had not broken my ankle
(it is possible to break an ankle and think its a bad sprain).

Fortunately not, so here I lie with my foot and a cushion and an ice
pack down my sock hoping it will not bugger up my holiday in 2 weeks!

So that probably went down as "lawnmower accident".

So when DIY lawn mowing is banned next year, blame me!

My dear chap, if all but sit-on mowers get banned as a result, I shall
put up a statue to you!

Careful, the numpties will insist on a on you passing a mowing test first...

--
Cheers,

John.

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

On 30/07/2014 18:14, harryagain wrote:
"Tim Streater" wrote in message
.. .
In article , harryagain
wrote:

"Jaffna Dog" wrote in message
...
On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,
common to all areas, what would, or could, it be? Still AC? 300 volts?
Different frequency?

[blank lines and other cockups caused by Mr. Paste using google groups,
fixed]

[long and irrelevant post by harry, deleted]

The point of your post was *what*, precisely, harry?

Some (obviously foreign) retard was drivelling on some crap about the
history of domestic energy in the UK


Wrong again Harry. It was a bit of blue-sky thinking about how it could
have developed if it hadn't developed in the way it actually did.

--
Colin Bignell

"Nightjar "cpb"@" "insert my surname here wrote in message
...
On 30/07/2014 18:14, harryagain wrote:
"Tim Streater" wrote in message
.. .
In article , harryagain
wrote:

"Jaffna Dog" wrote in message
...
On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,
common to all areas, what would, or could, it be? Still AC? 300 volts?
Different frequency?

[blank lines and other cockups caused by Mr. Paste using google groups,
fixed]

[long and irrelevant post by harry, deleted]

The point of your post was *what*, precisely, harry?

Some (obviously foreign) retard was drivelling on some crap about the
history of domestic energy in the UK


Wrong again Harry. It was a bit of blue-sky thinking about how it could
have developed if it hadn't developed in the way it actually did.


Drivel. It was posted as factual.

On 01/08/2014 08:53, harryagain wrote:
"Nightjar "cpb"@" "insert my surname here wrote in message
...
On 30/07/2014 18:14, harryagain wrote:
"Tim Streater" wrote in message
.. .
In article , harryagain
wrote:

"Jaffna Dog" wrote in message
...
On Sunday, 27 July 2014 20:12:35 UTC+1, David Paste wrote:

My question is that if we were to have a brand new electrical system,
common to all areas, what would, or could, it be? Still AC? 300 volts?
Different frequency?

[blank lines and other cockups caused by Mr. Paste using google groups,
fixed]

[long and irrelevant post by harry, deleted]

The point of your post was *what*, precisely, harry?

Some (obviously foreign) retard was drivelling on some crap about the
history of domestic energy in the UK


Wrong again Harry. It was a bit of blue-sky thinking about how it could
have developed if it hadn't developed in the way it actually did.


Drivel. It was posted as factual.



That only demonstrates that you didn't understand either the posting or
the basis for the whole thread.

--
Colin Bignell