Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

Thanks in advance,

David Paste.

David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

Thanks in advance,

David Paste.

The idea system would be 1.5Volts. Then we would be able to run
everything from D cells.

Bill

AC for simple long-distance transmission. High voltage so the same
power uses less current and therefore thinner cable. Actual voltage
some large multiple of 12 so you get easy submultiples for step-down
transformers. I'm agnostic about frequency, though 50Hz/3000rpm
"feels" righter than 60Hz/3600rpm.

All that is pushing me to 240v @ 50Hz

jgh

On 27/07/2014 20:12, David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

AC for national and local distribution certainly. 200 - 250V seems about
right, with plugs and socketry good for something in the region of 15A
gives capability of adequate appliance sizes while not requiring huge
cable sizes.

Not sure I have strong feelings about frequency. Higher gives greater
transformer efficiencies, but less ideal speeds for sych motors.



--
Cheers,

John.

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

On 27/07/2014 20:57, wrote:
AC for simple long-distance transmission...

Except for underwater cables, where it can cause unacceptable
transmission losses.

--
Colin Bignell

In article ,
David Paste writes:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

240V was too high for mains filament lamps. Now that they are gone,
there's no reason not to stay there or even go a little higher, to
reduce I²R losses back to substation. If we went to 250V, nothing
would need changing. If we were starting afresh, 300V or 350V would
be even better. (Nowadays, conductors are more expensive than their
insulation.) Nothing to choose between 50 or 60Hz. 100Hz would halve
the size of storage capacitors in PSU's, but has implications for
the size of mains synchronisation zones.

DC is too hard to handle at the power levels associated with a house.

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

On 27/07/14 21:08, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 20:57, wrote:
AC for simple long-distance transmission...

Except for underwater cables, where it can cause unacceptable
transmission losses.


And the problem of phase locking 2 large systems with a bit of wet string

On Sunday, July 27, 2014 8:12:35 PM UTC+1, David Paste wrote:

Hello all.
The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.
Distribution via high voltage AC, and now DC in places.
I understand why various areas of the world have these differences - due
to historical reasons, etc.
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?
No real reason to ask other than idle curiosity.
Thanks in advance,
David Paste.

If to run existing appliances, 230v. If if were done in say 1900, maybe a bit higher voltage to save copper.

Frequency? Maybe 200 or 400Hz. It cuts the cost of transformers, reservoir caps, speed control caps, motor caps. Also cuts the cost of some motors, but increases the cost of some. It would however mean increased cost of power station generators and using dc links between transmission zones - really need a spreadsheet to work out what frequency would give the lowest total cost.

AC for transformers, cheaper switches, longer lived lamps, etc etc. The main downside of ac is limited transmission zones, but long distance links are better dc now anyway.

I suspect multivoltage distribution around the house would make sense, adding 12v & 5v.


NT

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

On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), David Paste
wrote:

Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

Thanks in advance,

David Paste.

I doubt there's any such thing as an "ideal" system you could roll out
world-wide. There are pros and cons with all systems before you even
get to considering regional and national particularities.

On Sunday, July 27, 2014 9:50:16 PM UTC+1, Cursitor Doom wrote:
On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), 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?

I doubt there's any such thing as an "ideal" system you could roll out
world-wide. There are pros and cons with all systems before you even
get to considering regional and national particularities.

Any sane system can do the task. A large spreadsheet should be able to work out what's cheapest.


NT

On 27/07/2014 21:40, wrote:
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

It's losses in the dielectric, so it applies to underground cables too.
Dielectric losses in air are low.

On 27/07/2014 20:12, David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

When the national grid was established in the 1920s, AC was chosen for a
very good reason; its undoubted advantage for changing voltage, allowing
the use of very high voltages for long distance transmission. 50Hz was a
compromise frequency. Electric motors worked best at 25Hz and long
distance transmission has fewer losses at lower frequencies, but 25Hz
produced visible flicker in incandescent lamps while 100Hz gave
completely flicker-free lighting (some people can still detect flicker
at 50Hz) and allowed transformers to be built using less materials.

If we were starting from scratch, with today's technology, I suspect
that we might go for HVDC transmission for the supergrid, converting it
to AC for more local transmission and distribution. Otherwise, the
inevitable compromises needed for differing needs would probably end up
with us having much the same system as we have now.

If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner. There would also be an advantage to choosing a lower frequency,
which would reduce transmission losses (around 12% at lower voltages).
The flicker effect of a lower frequency could be overcome by mandating
only high frequency fluorescents or all LED lighting.

--
Colin Bignell

On 27/07/2014 21:50, Cursitor Doom wrote:
On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), David Paste


I doubt there's any such thing as an "ideal" system you could roll out
world-wide. There are pros and cons with all systems before you even
get to considering regional and national particularities.

+1

wrote in
:

On Sunday, July 27, 2014 9:50:16 PM UTC+1, Cursitor Doom wrote:
On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), 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?

I doubt there's any such thing as an "ideal" system you could roll
out world-wide. There are pros and cons with all systems before you
even get to considering regional and national particularities.

Any sane system can do the task. A large spreadsheet should be able to
work out what's cheapest.


NT


I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

In article ,
Nightjar \cpb\@ insert my surname here wrote:
On 27/07/2014 20:12, David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

When the national grid was established in the 1920s, AC was chosen for a
very good reason; its undoubted advantage for changing voltage, allowing
the use of very high voltages for long distance transmission. 50Hz was a
compromise frequency. Electric motors worked best at 25Hz and long
distance transmission has fewer losses at lower frequencies, but 25Hz
produced visible flicker in incandescent lamps while 100Hz gave
completely flicker-free lighting (some people can still detect flicker
at 50Hz) and allowed transformers to be built using less materials.

If we were starting from scratch, with today's technology, I suspect
that we might go for HVDC transmission for the supergrid, converting it
to AC for more local transmission and distribution. Otherwise, the
inevitable compromises needed for differing needs would probably end up
with us having much the same system as we have now.

If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner.

But you'd get absurdly high currents.

--
From KT24

Using a RISC OS computer running v5.18

On 27/07/2014 22:24, newshound wrote:
On 27/07/2014 21:40, wrote:
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

It's losses in the dielectric, so it applies to underground cables too.
Dielectric losses in air are low.

Like the man says, although the problem is significantly greater under
water. 30km is about the limit for AC transmission under water, which is
why our links to the continent are HVDC. Even then, the cables are very
specialised and there are IIRC only three manufacturers of HVDC
underwater cables in the world. That is a limiting factor on how many
offshore wind farms can be built, as they need HVDC underwater cable,
the manufacturers have a limited capacity and well filled order books,
while increasing capacity is not something that can be done overnight.

--
Colin Bignell

On 27/07/2014 22:27, charles wrote:
In article ,
Nightjar \cpb\@ insert my surname here wrote:
....
If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner.

But you'd get absurdly high currents.


Since when did being absurd dissuade the elfs?

--
Colin Bignell

In article , Tim Watts
scribeth thus
On 27/07/14 21:08, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 20:57, wrote:
AC for simple long-distance transmission...

Except for underwater cables, where it can cause unacceptable
transmission losses.


And the problem of phase locking 2 large systems with a bit of wet string

High power inverters at either end of the DC line...
--
Tony Sayer

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;!...

Seek ye here!...


http://new.abb.com/about/technology/dc-portal

--
Tony Sayer

In article 2,
DerbyBorn writes:
I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

In a typical wire, they move slower than that.
However, the wave-front of the movement is typically
within one order of magnitude of the speed of light.

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

On 27/07/14 22:24, Nightjar "cpb"@ insert my surname here wrote:
If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner. There would also be an advantage to choosing a lower frequency,
which would reduce transmission losses (around 12% at lower voltages).
The flicker effect of a lower frequency could be overcome by mandating
only high frequency fluorescents or all LED lighting.


That's going to be a big cable to my 3kW kettle and heater ;-)

There's something to be said for higher voltage = lower current and a
lower risk of fires.

25mm2 meter cables are bad enough - 125mm2 ??

On 27/07/14 22:46, Andrew Gabriel wrote:
In article 2,
DerbyBorn writes:
I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

In a typical wire, they move slower than that.
However, the wave-front of the movement is typically
within one order of magnitude of the speed of light.


50% of c for some random coax cable we had to measure the speed of
signal propagation in, back in our physics labs.

On 27/07/14 22:33, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 22:24, newshound wrote:
On 27/07/2014 21:40, wrote:
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

It's losses in the dielectric, so it applies to underground cables too.
Dielectric losses in air are low.

Like the man says, although the problem is significantly greater under
water. 30km is about the limit for AC transmission under water, which is
why our links to the continent are HVDC.

I thought it was more the issue that you cannot phase lock France and
the UK? So DC is a natural choice if you have to re-invert it. And if
you have to do that, might as well transmit in DC too.

Not saying your reason is not a good reason - I just thought it was a
secondary reason to a fairly immutable primary problem.

Even then, the cables are very
specialised and there are IIRC only three manufacturers of HVDC
underwater cables in the world. That is a limiting factor on how many
offshore wind farms can be built, as they need HVDC underwater cable,
the manufacturers have a limited capacity and well filled order books,
while increasing capacity is not something that can be done overnight.

On 27/07/14 22:40, tony sayer wrote:
In article , Tim Watts
scribeth thus
On 27/07/14 21:08, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 20:57, wrote:
AC for simple long-distance transmission...

Except for underwater cables, where it can cause unacceptable
transmission losses.


And the problem of phase locking 2 large systems with a bit of wet string

High power inverters at either end of the DC line...


Exactly...

On Sun, 27 Jul 2014 21:25:51 GMT, DerbyBorn
wrote:

wrote in
:

On Sunday, July 27, 2014 9:50:16 PM UTC+1, Cursitor Doom wrote:
On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), 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?

I doubt there's any such thing as an "ideal" system you could roll
out world-wide. There are pros and cons with all systems before you
even get to considering regional and national particularities.

Any sane system can do the task. A large spreadsheet should be able to
work out what's cheapest.


NT


I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

As fast as that?
Typical drift speed is less than 1mm/s

--

Graham.

%Profound_observation%

On 27/07/2014 23:49, Tim Watts wrote:
On 27/07/14 22:33, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 22:24, newshound wrote:
On 27/07/2014 21:40, wrote:
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

It's losses in the dielectric, so it applies to underground cables too.
Dielectric losses in air are low.

Like the man says, although the problem is significantly greater under
water. 30km is about the limit for AC transmission under water, which is
why our links to the continent are HVDC.

I thought it was more the issue that you cannot phase lock France and
the UK? So DC is a natural choice if you have to re-invert it. And if
you have to do that, might as well transmit in DC too.

Not saying your reason is not a good reason - I just thought it was a
secondary reason to a fairly immutable primary problem.

I think the electricity actually needs to reach the other end of the
cable before phase locking becomes a problem :-)


--
Colin Bignell

On Sun, 27 Jul 2014 21:25:51 GMT, DerbyBorn
wrote:

wrote in
:

On Sunday, July 27, 2014 9:50:16 PM UTC+1, Cursitor Doom wrote:
On Sun, 27 Jul 2014 12:12:35 -0700 (PDT), 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?

I doubt there's any such thing as an "ideal" system you could roll
out world-wide. There are pros and cons with all systems before you
even get to considering regional and national particularities.

Any sane system can do the task. A large spreadsheet should be able to
work out what's cheapest.


NT


I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

Splutter!!! That's around about 5 or 6 orders of magnitude faster
than the typical drift speed of electrons in a copper cable carrying 5
amps in a 1mm diameter conductor (about 0.75 mm squared CSA). Were
you, perhaps, thinking of using superconducting cables?
--
J B Good

On 27/07/2014 22:46, Andrew Gabriel wrote:
In article 2,
DerbyBorn writes:
I sometimes stay awake at night wondering how it would be if electrons only
went at about 100mph!!

In a typical wire, they move slower than that.

Yup, they don't call it "electron drift" for nothing!

However, the wave-front of the movement is typically
within one order of magnitude of the speed of light.



--
Cheers,

John.

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

On Sun, 27 Jul 2014 23:46:14 +0100, Tim Watts wrote:

If I move into very hypothetical areas, I could possibly see a
move to
have residential areas supplied at 50v or less, under the elfen
safety
banner.

That's going to be a big cable to my 3kW kettle and heater ;-)

Even bigger for 10 kW of storage heating... 40 odd amps at 230 V for
a few hours makes the tails warm. The 200 A required for a 50 V
supply is getting hard to handle.

--
Cheers
Dave.

On 27/07/14 21:08, Nightjar "cpb"@ insert my surname here wrote:
On 27/07/2014 20:57, wrote:
AC for simple long-distance transmission...

Except for underwater cables, where it can cause unacceptable
transmission losses.


Actually the ONLY - but overwhelming - advantage of AC is that it can
be transformed in terms of voltage by Victorian technology.

The disadvantages a

- it radiates
- it suffers capacitative current flow that induces extra losses in the
resistive cables
- it suffers out of phase losses when ringed over very long distances -
continent sized.
- it causes muscle spasms in shock situations.
- it it isn't especially useful in motor situations.

Now that we have reasonably efficient DC to DC converters its is likely
it won't be used that much more outside national scale grids..

All medium length underwater and all long length transcontinental inks
are now DC

USB style 5V DC power is becoming a de facto standard in low power home
situations.




--
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 27/07/14 21:40, wrote:
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.


The conductive medium surrounding it means that unlike a 132kV cable
string 50 meters in the air, there is considerable capacitance to
ground. Only the cable insulation stand between it and ground, and a
conductive - a very conductive - ground.

The pout of phase current isn't loss in itself, but it does mean higher
currents in the wire for the same power output at the far end and higher
currents mean higher resistive losses.


jgh



--
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 27/07/14 22:24, newshound wrote:
On 27/07/2014 21:40, wrote:
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

It's losses in the dielectric, so it applies to underground cables too.
Dielectric losses in air are low.

No it really isn't dielectric losses.


--
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 27/07/14 22:24, Nightjar "cpb"@ insert my surname here wrote:
If we were starting from scratch, with today's technology, I suspect
that we might go for HVDC transmission for the supergrid, converting it
to AC for more local transmission and distribution. Otherwise, the
inevitable compromises needed for differing needs would probably end up
with us having much the same system as we have now.

WE already are doing this. The cost benefit analysis for DC versus AC is
changing as inverter and rectifier costs come down.


That balances with rising costs of electricity and therefore electrical
losses in AC circuits.

DC is already preferred for long intergrid links and those spinning
offshore white elephants.

Its also the only sane way to connect grids that are not in phase - and
that's something IIRC that is an issue over continental grids like the
US which is again IIRC more than one grid at different phases.

There is a very good case for domestic DC and in fact that's happening
too with USB style sockets being handy for LV electronics.



--
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 27/07/14 22:27, charles wrote:
In article ,
Nightjar \cpb\@ insert my surname here wrote:
On 27/07/2014 20:12, David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

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?

No real reason to ask other than idle curiosity.

When the national grid was established in the 1920s, AC was chosen for a
very good reason; its undoubted advantage for changing voltage, allowing
the use of very high voltages for long distance transmission. 50Hz was a
compromise frequency. Electric motors worked best at 25Hz and long
distance transmission has fewer losses at lower frequencies, but 25Hz
produced visible flicker in incandescent lamps while 100Hz gave
completely flicker-free lighting (some people can still detect flicker
at 50Hz) and allowed transformers to be built using less materials.

If we were starting from scratch, with today's technology, I suspect
that we might go for HVDC transmission for the supergrid, converting it
to AC for more local transmission and distribution. Otherwise, the
inevitable compromises needed for differing needs would probably end up
with us having much the same system as we have now.

If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner.

But you'd get absurdly high currents.


Well only x5 on what we have now...





--
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 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..

Seek ye here!...


http://new.abb.com/about/technology/dc-portal



--
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 27/07/14 23:46, Tim Watts wrote:
On 27/07/14 22:24, Nightjar "cpb"@ insert my surname here wrote:
If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner. There would also be an advantage to choosing a lower frequency,
which would reduce transmission losses (around 12% at lower voltages).
The flicker effect of a lower frequency could be overcome by mandating
only high frequency fluorescents or all LED lighting.


That's going to be a big cable to my 3kW kettle and heater ;-)

There's something to be said for higher voltage = lower current and a
lower risk of fires.

its about power not current


25mm2 meter cables are bad enough - 125mm2 ??

well exactly. its bad enough wiring up three x 50W 12v halogens..


--
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 27/07/14 23:49, Tim Watts wrote:
I thought it was more the issue that you cannot phase lock France and
the UK? So DC is a natural choice if you have to re-invert it. And if
you have to do that, might as well transmit in DC too.

Not saying your reason is not a good reason - I just thought it was a
secondary reason to a fairly immutable primary problem.

No. I visited the first link to france at the UK end and the issue is
primarily one of losses

'we can draw an arc for 30 minutes off the capacitance in that cable'

To drive that capacitance takes a LOT of out of phase current and that
suffers resistive losses.

Big ones



--
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 28/07/2014 01:23, Dave Liquorice wrote:
On Sun, 27 Jul 2014 23:46:14 +0100, Tim Watts wrote:

If I move into very hypothetical areas, I could possibly see a
move to
have residential areas supplied at 50v or less, under the elfen
safety
banner.

That's going to be a big cable to my 3kW kettle and heater ;-)

Even bigger for 10 kW of storage heating... 40 odd amps at 230 V for
a few hours makes the tails warm. The 200 A required for a 50 V
supply is getting hard to handle.


For a H&S viewpoint, an ELV domestic system would save around 20-25
domestic deaths and around a third of a million serious injuries from
electrocution every year.

--
Colin Bignell

On 28/07/2014 01:23, Dave Liquorice wrote:
On Sun, 27 Jul 2014 23:46:14 +0100, Tim Watts wrote:

If I move into very hypothetical areas, I could possibly see a
move to
have residential areas supplied at 50v or less, under the elfen
safety
banner.

That's going to be a big cable to my 3kW kettle and heater ;-)

Even bigger for 10 kW of storage heating... 40 odd amps at 230 V for
a few hours makes the tails warm. The 200 A required for a 50 V
supply is getting hard to handle.


If we were starting entirely from scratch and ELV domestic supplies were
considered desirable, would we allow such an inefficient heating system,
or would we mandate something more efficient, such as a heat pump?
Staring from a clean slate, there might be any number of things that
would be done differently from what we have evolved over time.

--
Colin Bignell