Electrical Engineering - Which Residential Voltage & Frequency Arrangement Is Best?

Author

Which Residential Voltage & Frequency Arrangement Is Best?

Nehmo

2006-03-18, 4:21 pm

For residential electrical use, there are two basic voltage & AC
frequency systems across the world, http://kropla.com/electric2.htm.
Does one have an advantage over the other? In other words, if you were
starting from scratch and could impose a world standard, what would you
choose?

What voltage and what frequency?
--
(||) Nehmo (||)

dennis@home

2006-03-18, 5:21 pm

Derek ^

2006-03-18, 5:21 pm

On 18 Mar 2006 12:13:35 -0800, "Nehmo" <nehmo54@hotmail.com> wrote:

>For residential electrical use, there are two basic voltage & AC
>frequency systems across the world, http://kropla.com/electric2.htm.
>Does one have an advantage over the other? In other words, if you were
>starting from scratch and could impose a world standard, what would you
>choose?
>
>What voltage and what frequency?

As regards voltage 230 ever time. Permits effective high powered small
appliances, kettles etc.

The Americans wire 110-0-110 (=220) into fixed appliances such as
stoves and aircon.

110v has no electrical shock safety advantage over 220/230v. If it
would not be safe at 220v, it could not be relied on to be safe at
110v.

The 230v standard does have significantly lower fire risk, (half the
current for the same power).

A typical American wooden built house with aluminium wiring and 110
volts = "Giant Firework"

As regards frequency there's not much in it. Iron losses in
transformers increase with frequency., but fluorescent Tubes flicker
less at 60Hz (however increasingly nowadays fluorescent tube ballast
are high frequency solid state devices, so this wouldn't then count).

Similarly TV's scanning at 60Hz, but AFAIK since colour they are not
mains locked any more, but they probably don't move that far away from
the local mains freq. to avoid mains intereference running through the
picture. Refreshing the pictures at 60Hz uses 20% more bandwidth than
50Hz, hence the American 525 line standard and our 625lines.

DG

sanjian

2006-03-18, 5:21 pm

Nehmo wrote:
> For residential electrical use, there are two basic voltage & AC
> frequency systems across the world, http://kropla.com/electric2.htm.
> Does one have an advantage over the other? In other words, if you were
> starting from scratch and could impose a world standard, what would
> you choose?
>
> What voltage and what frequency?

Generally, higher voltage is good, because it carries a lower current for
the given power. Of course, higher voltage also increases the possiblity of
arcing (IIRC, I was a mechanic, not an electrician), so a balance needs to
be struck. I say go with 450V.

Andrew Gabriel

2006-03-18, 5:21 pm

In article <1142712815.334466.199660@z34g2000cwc.googlegroups.com>,
"Nehmo" <nehmo54@hotmail.com> writes:
> For residential electrical use, there are two basic voltage & AC
> frequency systems across the world, http://kropla.com/electric2.htm.
> Does one have an advantage over the other? In other words, if you were
> starting from scratch and could impose a world standard, what would you
> choose?
>
> What voltage and what frequency?

You're posting from google. If you do a google search first,
you'll find this has already been done to death, many times
over.

Good night.
--
Andrew Gabriel

Beachcomber

2006-03-18, 7:21 pm

On Sat, 18 Mar 2006 20:50:05 +0000, Derek ^
<usenet@miniac.demon.co.uk> wrote:

>On 18 Mar 2006 12:13:35 -0800, "Nehmo" <nehmo54@hotmail.com> wrote:
>
>
>As regards voltage 230 ever time. Permits effective high powered small
>appliances, kettles etc.
>
>The Americans wire 110-0-110 (=220) into fixed appliances such as
>stoves and aircon.

The North American system has the advantage that both 120 and 240 volt
circuits are available for both fixed and portable appliances. One
sees the 240 volt outlets mostly in workshops, farms (for heavy duty
electric heaters, or for commecial installations (restaurant
applicances, for example). 240 volt circuits are common for air
conditioners, dryers, electric ovens, and water well pumps and
heavy-duty power tools.

Some Brits are fond of saying that, with our system, we who live in
North America can't operate that power hungry deep fat fryer in our
kitchens with our wimpy 120 volt appliance circuits. The truth is we
seldom miss it. A deluxe kitchen can easily be constructed with a 240
V. outlet for commerical kitchen appliances, if desired.

All American kitchens are required to have at least two 20A 120 volt
appliance circuits for a total of (at least) 4800 watts available.
These seems to do a good job powering the toasters, microwave ovens,
mixers, can openers, and electric grills that are commonly used.
Also, when the design calls for more power, an additional circuit is
installed

Probably the biggest safety advantage of the North American system is
that in no room of any house is there a conductor with greater than
125 volts potential to earth ground (even though 240 volts is
available where required). This applies to kitchens, bedrooms,
bathrooms, hot tubs, garages...everywhere.

>
>110v has no electrical shock safety advantage over 220/230v. If it
>would not be safe at 220v, it could not be relied on to be safe at
>110v.

In theory yes... but if you've actually been the recipient of a shock
at 220 - 230 volt, it is comparatively more painful, (and more
difficult to let go of) than 110-120 v.

If what you are saying were true, there would be no need for the 50 -
0 - 50 volt scheme that is used for UK power tools on construction
sites. ... If there are 240 V. appliances... why not 240 V. power
tools? There is a reason for this.

In contrast, modern 120 v. power tools are considered electrically
safe in North America. (This was not always the case before universal
grounding, double insulation, and the requirement for GFCI
(differential) circuit protectors).
>
>The 230v standard does have significantly lower fire risk, (half the
>current for the same power).
>
There is a tradeoff between voltage and current. The downside of the
higher voltage is that insulation requirements are higher and the
physical spacing between two conductors at devices such as a plug must
be greater (hence the device must be physically larger).

I like the design of the Shuko plug and receptacle. It seems safe and
is well designed for a 230 volt circuit. It's just not very elegant
when you put them in a power strip, for example. The whole thing is
just too big.

Also, speaking of fire risk... Because of the comparative difficulty
of making low wattage incandescent light filaments at 240 volts, these
lamps tend to run a super hot temperatures (when compared to
equivalent 120 volt incandescent lamps with a similar light output).

I'm sure that the UK is well on its way to converting to compact
fluorescents, but I'm also sure that many of these super hot
incandescents are still in use.

>A typical American wooden built house with aluminium wiring and 110
>volts = "Giant Firework"

Aluminum (same element -different spelling) wire for US residential
branch ciruits has not been used for decades. It was recognized as a
problem and there have have been wiring techniques developed to make
retrofit installations safer.

Aluminum and Aluminum alloys are commonly used for service entrance
cable and are even considered to be safer than copper. In the event
of a rare, direct short, the aluminum cable will eventually melt and
break the current. The copper is likely to get insanely hot, but keep
the current flowing for a much longer time- so I'm told.

>As regards frequency there's not much in it. Iron losses in
>transformers increase with frequency., but fluorescent Tubes flicker
>less at 60Hz (however increasingly nowadays fluorescent tube ballast
>are high frequency solid state devices, so this wouldn't then count).
>
50 Hz flicker is visible in low wattage incandescent bulbs. The
filament just cools too fast. This is one of the reasons the higher
60 Hz frequency was chosen for the North American System.

>Similarly TV's scanning at 60Hz, but AFAIK since colour they are not
>mains locked any more, but they probably don't move that far away from
>the local mains freq. to avoid mains intereference running through the
>picture. Refreshing the pictures at 60Hz uses 20% more bandwidth than
>50Hz, hence the American 525 line standard and our 625lines.
>
>DG
>
TV's require precisely locked oscillators, which were difficult to
design and stablize in the 1940's and 1950's, hence, the TV's of the
time were locked to the local line frequency. This represented the
most accurate time base of the time.

Oscillators got better and more stable with the introduction of solid
state circuits and crystals. No modern TV need to use the power line
for an external time base reference.

Beachcomber

The Natural Philosopher

2006-03-18, 9:21 pm

Nehmo wrote:
> For residential electrical use, there are two basic voltage & AC
> frequency systems across the world, http://kropla.com/electric2.htm.
> Does one have an advantage over the other? In other words, if you were
> starting from scratch and could impose a world standard, what would you
> choose?
>
> What voltage and what frequency?

48v 0Hz (DC)

Since just about everything uses SMPS theses days - even lights - why
have AC at all - and 48v is pretty much safer, especially DC.

The consumer unity has a 200A bridge rectifier and a bank of capacitors
in it, and a power factor correction inductor. :D

No nasty interference either.

SQLit

2006-03-18, 9:21 pm

"Derek ^" <usenet@miniac.demon.co.uk> wrote in message
news:baro129suqsjfjd4ci71gt41vsg277nk9q@4ax.com...
> On 18 Mar 2006 12:13:35 -0800, "Nehmo" <nehmo54@hotmail.com> wrote:
>
>
> As regards voltage 230 ever time. Permits effective high powered small
> appliances, kettles etc.
>
> The Americans wire 110-0-110 (=220) into fixed appliances such as
> stoves and aircon.
>
> 110v has no electrical shock safety advantage over 220/230v. If it
> would not be safe at 220v, it could not be relied on to be safe at
> 110v.
>
> The 230v standard does have significantly lower fire risk, (half the
> current for the same power).
>
> A typical American wooden built house with aluminium wiring and 110
> volts = "Giant Firework"
>

AL wiring inside homes has not been around since the late 1970's. Better
dust off your "way back machine"
http://www.codecheck.com/wiring_history.htm

Please provide documentation for "230v standard does have significantly
lower fire risk".

raden

2006-03-18, 9:21 pm

In message <c52Tf.33$uY2.650@news.uswest.net>, SQLit <sqlit@qwest.net>
writes
>
>"Derek ^" <usenet@miniac.demon.co.uk> wrote in message
>news:baro129suqsjfjd4ci71gt41vsg277nk9q@4ax.com...
>
>AL wiring inside homes has not been around since the late 1970's. Better
>dust off your "way back machine"
>http://www.codecheck.com/wiring_history.htm
>
>Please provide documentation for "230v standard does have significantly
>lower fire risk".
>
It's all to do with currants raisin the heat

--
geoff

meow2222@care2.com

2006-03-18, 10:21 pm

Beachcomber wrote:
> On Sat, 18 Mar 2006 20:50:05 +0000, Derek ^
> <usenet@miniac.demon.co.uk> wrote:

Right! I challenge you to an armwrestle.
[color=darkred]
>
> The North American system has the advantage that both 120 and 240 volt
> circuits are available for both fixed and portable appliances. One
> sees the 240 volt outlets mostly in workshops, farms (for heavy duty
> electric heaters, or for commecial installations (restaurant
> applicances, for example). 240 volt circuits are common for air
> conditioners, dryers, electric ovens, and water well pumps and
> heavy-duty power tools.

The presence of 2 voltages is a disadvantage, because it restricts what
can be plugged in where, and increases the amount of wiring required.
Everything on 240 makes better sense. We used to have a 4 plug system,
with 2A 5A and 15A 3 pin plugs, plus 5A 2 pins. What a horror it was: a
single universal socket is a significant advantage.

> Some Brits are fond of saying that, with our system, we who live in
> North America can't operate that power hungry deep fat fryer in our
> kitchens with our wimpy 120 volt appliance circuits. The truth is we
> seldom miss it. A deluxe kitchen can easily be constructed with a 240
> V. outlet for commerical kitchen appliances, if desired.

all ours have 3kW outlets, theyre universal, no extra cost.

> All American kitchens are required to have at least two 20A 120 volt
> appliance circuits for a total of (at least) 4800 watts available.
> These seems to do a good job powering the toasters, microwave ovens,
> mixers, can openers, and electric grills that are commonly used.

I'm surprised, I though you were a real power hungry nation. We have at
least one 30A 240v circuit in every kitchen, 7.2kW.

> Also, when the design calls for more power, an additional circuit is
> installed
>
> Probably the biggest safety advantage of the North American system is
> that in no room of any house is there a conductor with greater than
> 125 volts potential to earth ground (even though 240 volts is
> available where required). This applies to kitchens, bedrooms,
> bathrooms, hot tubs, garages...everywhere.

IRL its not a safety advantage. People think they can get away with
things they wouldnt dare do here, and the result is more deaths, not
less. Our system is specced to (mostly) higher safety standards partly
because it needs to be. 240 is not to be messed with, and everyone
knows it.

>
> In theory yes... but if you've actually been the recipient of a shock
> at 220 - 230 volt, it is comparatively more painful, (and more
> difficult to let go of) than 110-120 v.

yes, hence the differing attitudes towards it. The US routinely does
various things with electrics that are illegal here on safety grounds.

> If what you are saying were true, there would be no need for the 50 -
> 0 - 50 volt scheme that is used for UK power tools on construction
> sites. ... If there are 240 V. appliances... why not 240 V. power
> tools? There is a reason for this.

There is no need for 55-0-55 onsite, we do use 240v tools onsite. 110v
tools are a historic thing. With RCDs we no longer worry about using
240v on a wet site so much, whereas before RCDs, in wet conditions, it
was a clear risk - as of course 110 would be, though less. Hence we
went with 55v.

> In contrast, modern 120 v. power tools are considered electrically
> safe in North America. (This was not always the case before universal
> grounding, double insulation, and the requirement for GFCI
> (differential) circuit protectors).
> There is a tradeoff between voltage and current. The downside of the
> higher voltage is that insulation requirements are higher

I'm not sure thats a downside, really it depends on your material
resources as to what voltage cable is most economical. IIUC America has
a lot more copper availability than here, so we spend more on the
plastic and less on the copper. Fwiw a century ago copper cable was
considered excessively expensive, and steel cable was sometimes used.
Steel makes truly bad cable, illustrating the high cost of copper.

> and the
> physical spacing between two conductors at devices such as a plug must
> be greater

larger spacing is needed, but its not a downside in any way.

> (hence the device must be physically larger).

no, not at all. The spacings involved are small compared with plugtop
sizes, it really makes no difference to plug size. Our huge plugs are a
British oddity I would definitely not repeat if starting from scratch.

IEC plugs/sockets might be good if they were metal sleeved, using the
sleeve to connect earth.

> I like the design of the Shuko plug and receptacle. It seems safe and
> is well designed for a 230 volt circuit. It's just not very elegant
> when you put them in a power strip, for example. The whole thing is
> just too big.

Our plugs seem to be an oddity of history. At least theyre a bit better
than the South African plug, which is the one we quit using half a
century ago. But the US ones are very poorly specced, a recipe for
trouble.

I'd like to see a 2 pin version of our square pin plugs. Compatible,
cheap, space saving, material and energy saving.

> Also, speaking of fire risk... Because of the comparative difficulty
> of making low wattage incandescent light filaments at 240 volts, these
> lamps tend to run a super hot temperatures (when compared to
> equivalent 120 volt incandescent lamps with a similar light output).

no no. Higher R requirement means a thinner filament, and this is run
at lower temp to slow down evaporation, as there isnt much to
evaporate. The filament runs cooler: this has insignificant bearing on
the temperature of the glass bulb. This is only an issue for 25w and
15w bulbs, the higher wattage ones perform better.

> I'm sure that the UK is well on its way to converting to compact
> fluorescents, but I'm also sure that many of these super hot
> incandescents are still in use.

110v is closer to the ideal efficacy voltage for house bulbs. But of
course there are better solutions.

>
> Aluminum (same element -different spelling) wire for US residential
> branch ciruits has not been used for decades. It was recognized as a
> problem and there have have been wiring techniques developed to make
> retrofit installations safer.
>
> Aluminum and Aluminum alloys are commonly used for service entrance
> cable and are even considered to be safer than copper. In the event
> of a rare, direct short, the aluminum cable will eventually melt and
> break the current. The copper is likely to get insanely hot, but keep
> the current flowing for a much longer time- so I'm told.

In a short a fuse would blow. If it ever gets to the stage where the
incoming cable melts, the system design has failed badly, and was a
duff design. IRL this isnt a significant failure mode.

Ali expands and contracts, loosening connections. Then when its not gas
tight it oxidises. The resulting resistance produces heat and more
oxidation... your ali supplies are not an advantage. We still have
incomers that are near a century old, with PBJ etc insulation.

> 50 Hz flicker is visible in low wattage incandescent bulbs. The
> filament just cools too fast. This is one of the reasons the higher
> 60 Hz frequency was chosen for the North American System.

The real difference with frequency is the enormous tonnage of iron used
in transformers, ballasts and motors. 60Hz is definitely better than
50, and 100 better again. Theres a tradeoff because higher frequencies
reduce the maximum service area, which causes problems for the power
cos. Also very much higher f and laminated transformers would become
too lossy. Increasing f, upto a point, would reduce the size and losses
of transformers, motors, and ballasts.

IIUC the US got 525 lines in the 50s, we got 625 in the 60s, as much
down to technical progress as anything. Same with the colour system,
PAL is much better than NTSC, because we waited longer before
implementing colour.

[color=darkred]
> TV's require precisely locked oscillators, which were difficult to
> design and stablize in the 1940's and 1950's, hence, the TV's of the
> time were locked to the local line frequency. This represented the
> most accurate time base of the time.
>
> Oscillators got better and more stable with the introduction of solid
> state circuits and crystals. No modern TV need to use the power line
> for an external time base reference.

I think this is a myth. The main oscs in a tv are line and frame.
(There are also rf, psu and colour oscs.) Line oscs have always been
synched to the received signal, first by hard locked sync, later by
flywheel sync. Frame scans have always been locked to received signal
too. Initially the last line on the frame was 1.5 lines long, and the
field scan locked to this. This was changed to work with the much
better flywheel system, all lines became the same length, the frame osc
had to lock to the differing sync pulses.

The reason to keep frame rate and mains freq locked _at the tx end_ is
to avoid noticing the frequency difference ripple moving the picture
about, which is liable to happen on old kit, and looks rather bad. A
fixed distortion OTOH is hardly noticeable, especially on early sets
that were inherently much more geometrically distorted than modern
flatter CRTs. There has never been power line lock at the receiving
end, not with 405 or 625 lines. Perhaps it got implemented on the
earlier 30 line mechanical system, whch was otherwise syncless.

NT

Beachcomber

2006-03-18, 11:21 pm

>
>The presence of 2 voltages is a disadvantage, because it restricts what
>can be plugged in where, and increases the amount of wiring required.
>Everything on 240 makes better sense. We used to have a 4 plug system,
>with 2A 5A and 15A 3 pin plugs, plus 5A 2 pins. What a horror it was: a
>single universal socket is a significant advantage.

You said later in your post and I quote "110v is closer to the ideal
efficacy voltage for house bulbs" so that is at least one reason for
having the lower voltage. Not all the world has gone over to compact
fluorescents and there are some applications where they might be
downright undesirable.

I have already argued that safety is another reason.
>
>
>
>all ours have 3kW outlets, theyre universal, no extra cost.
>
>
>
>I'm surprised, I though you were a real power hungry nation. We have at
>least one 30A 240v circuit in every kitchen, 7.2kW.

The North American Codes specify that no point on the kitchen counter
should be less than 3 ft. from an outlet. In my small modest 15 x 15
kitchen I count no less than 9 duplex outlets (18 outlets total).
Our codes are concerned with safety, not convenience, but in this
case, the idea is not to be plugging toasters and other high current
appliance into extension cords. You can't even buy a toaster in the
US anymore with a cord longer than 3 feet. Ever see those movies
from the thirties were the appliances were plugged into the pendant
socket hanging from the ceiling? Apparently, that was real bad...

We are not necessarily power hungry, but there are lots of appliances
that may not necessarily be in use at the same time in a modern
kitchen. The requirement for at least two 20A circuits and the
requirement for many outlets serve the need.

I will conceed that those ring main circuits do allow you to power
that 7.2 kW deep fryer though.... Something we can't do without extra
effort.

The most bizarre Euro power setup I ever saw was in the apartment I
rented in Paris about 10 years ago. That French "Disjouncter" or
whatever they call it would ration the power to the point where I
could not have my water heater working if certain other routine loads
where online at the same time. This was true even though the total
load was much less than the installed capacity. They just didn't want
you to be using too much power.

It reminded me of the episode of the American TV Series Green Acres
called "You can't plug in a 6 with a 2". Farmer Douglas tried to
explain to his wife Lisa that all the power cords for the kitchen
appliances had numbers on them corresponding to the size and current
consumption of the device. If you went over 7, the generator outside
the farm would start on fire.

[color=darkred]
>
>IRL its not a safety advantage. People think they can get away with
>things they wouldnt dare do here, and the result is more deaths, not
>less. Our system is specced to (mostly) higher safety standards partly
>because it needs to be. 240 is not to be messed with, and everyone
>knows it.

I stand by my original statement. We don't have many people in the US
that say, "Gee it's only 120 volts... I don't respect it". Some...
but not many.

120 volts is safer than 220V. just as 220V is safer than 480V.

>
>yes, hence the differing attitudes towards it. The US routinely does
>various things with electrics that are illegal here on safety grounds.
>
The same could be said for some of the UK practices from what I've
read.

Whether it's 120V or 240V, the N.A. codes say that we don't put these
voltages in the shower. We don't even go near 240 volts in the
bathroom. Other than lighting and a bathroom heater, there is only
one allowed a GFCI protected outlet by the sink for a shaver or hair
dryer. Some homes have electric outlets by the toilet. That is if
you have one of those fancy TOTO models that sprays warm water up your
arse.
>

Beachcomber

Don Kelly

2006-03-19, 1:21 am

----------------------------
"dennis@home" <dennis@killspam.kicks-XXX.net> wrote in message
news:j7_Sf.38034$wl.20986@text.news.blueyonder.co.uk...
> Nehmo wrote:
>
> 400hz 100V

And how do you get 400Hz to a home or industry? It is inferior to either 50
or 60 Hz for transmission and distribution. It does have advantages in
aircraft but that 's about it.
As to 100V- worsens the situation.

I hope that you are not serious.

--

Don Kelly @shawcross.ca
remove the X to answer

>
>

Don Kelly

2006-03-19, 1:21 am

----------------------------
"The Natural Philosopher" <a@b.c> wrote in message
news:1142729776.87265.5@despina.uk.clara.net...
> Nehmo wrote:
>
> 48v 0Hz (DC)
>
> Since just about everything uses SMPS theses days - even lights - why have
> AC at all - and 48v is pretty much safer, especially DC.
>
> The consumer unity has a 200A bridge rectifier and a bank of capacitors in
> it, and a power factor correction inductor. :D
>
> No nasty interference either.
------------------------------
You must be kidding!

Don Kelly @shawcross.ca
remove the X to answer

The Natural Philosopher

2006-03-19, 6:21 am

Don Kelly wrote:
> ----------------------------
> "The Natural Philosopher" <a@b.c> wrote in message
> news:1142729776.87265.5@despina.uk.clara.net...
> ------------------------------
> You must be kidding!
>

Soirta, but actually, inside a house, its about ideal.,

Useless for transmission tho. Stick to 50Hz there. Or HVDC and inverters...

> Don Kelly @shawcross.ca
> remove the X to answer
>
>

tony sayer

2006-03-19, 6:21 am

>Probably the biggest safety advantage of the North American system is[color=darkred]
>that in no room of any house is there a conductor with greater than
>125 volts potential to earth ground (even though 240 volts is
>available where required). This applies to kitchens, bedrooms,
>bathrooms, hot tubs, garages...everywhere.
>

And with whole house RCD protection the UK 230 volt system is no worse
at all....

--
Tony Sayer

tony sayer

2006-03-19, 7:21 am

>Ali expands and contracts, loosening connections. Then when its not gas
>tight it oxidises. The resulting resistance produces heat and more
>oxidation... your ali supplies are not an advantage. We still have
>incomers that are near a century old, with PBJ etc insulation.

Odd that steel cored ally cable is use on the national grid at
400 kV!.....
--
Tony Sayer

Tony Williams

2006-03-19, 7:21 am

In article <1142729776.87265.5@despina.uk.clara.net>,
The Natural Philosopher <a@b.c> wrote:

> 48v 0Hz (DC)

> Since just about everything uses SMPS theses days - even lights -
> why have AC at all - and 48v is pretty much safer, especially DC.

I think the 'mains' in some modern helicopters is
about a 270Vdc bus, generated by one central 3-phase
rectifier on the 200V L-L AC. Saves a sigificant
amount of weight in both the generation and consumers.
I have no idea how they switch 270Vdc though.

--
Tony XXXXXXXX.

The Natural Philosopher

2006-03-19, 7:21 am

Tony XXXXXXXX wrote:
> In article <1142729776.87265.5@despina.uk.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>
>
>
> I think the 'mains' in some modern helicopters is
> about a 270Vdc bus, generated by one central 3-phase
> rectifier on the 200V L-L AC. Saves a sigificant
> amount of weight in both the generation and consumers.
> I have no idea how they switch 270Vdc though.
>
MOSFETS are able to go that high..450V MOSFETS are made in vast
quantities for mains voltage SMPS.

tony sayer

2006-03-19, 7:21 am

In article <4e0a000d56tonyw@ledelec.demon.co.uk>, Tony XXXXXXXX
<tonyw@ledelec.demon.co.uk> writes
>In article <1142729776.87265.5@despina.uk.clara.net>,
> The Natural Philosopher <a@b.c> wrote:
>
>
>
> I think the 'mains' in some modern helicopters is
> about a 270Vdc bus, generated by one central 3-phase
> rectifier on the 200V L-L AC. Saves a sigificant
> amount of weight in both the generation and consumers.
> I have no idea how they switch 270Vdc though.
>

Wonder why such a high voltage, its not that transmission losses will be
all that great ?....
--
Tony Sayer

sanjian

2006-03-19, 10:21 am

The Natural Philosopher wrote:
> Don Kelly wrote:
>
> Soirta, but actually, inside a house, its about ideal.,
>
> Useless for transmission tho. Stick to 50Hz there. Or HVDC and
> inverters...

Except that, for the same function, AC motors are smaller, lighter, and
cheaper. Which means you're unlikely to see DC in use.

Beachcomber

2006-03-19, 11:21 am

On Sun, 19 Mar 2006 10:11:42 +0000, tony sayer <tony@bancom.co.uk>
wrote:

>
>And with whole house RCD protection the UK 230 volt system is no worse
>at all....
>

Do the UK whole house RCD's shut off the whole house power when they
trip?

If so, that sounds like it might be awfully inconvenient at best and
possible dangerous if they should trip at night and leave the
occupants stumbling around in the dark.

In the North American System, they are called GFI's (sometimes GFCI's)
Ground Fault Circuit Interrupters and standard practice is to place
them on individual branch circuits (15 or 20 A) as combo GFI/circuit
breakers or as stand alone units that are also duplex outlets. The
latter may be wired to protect other downstream devices. There is a
special, very expensive, GFI that must be used for hot tub
installations.

The point is...this allows the system to be selective about what to
protect with a GFI. Generally, critical loads such as refrigerators,
sump pumps, and fire pumps are never wired with GFI's to prevent
nuisance tripping from current leakage caused by old wiring. The
trip point on these standard devices is set at 5 ma and is normally
not adjustable.

Other outlets and devices are required by the code to be wired with a
GFI including bathroom and kitchen outlets, plus outdoor and garage
receptacles. There is a new rule that bedroom outlets must be wired
with arc-fault protectors.

Beachcomber

Bob Eager

2006-03-19, 11:21 am

On Sun, 19 Mar 2006 14:29:36 UTC, not_real@xxx.yyy (Beachcomber) wrote:

>
> Do the UK whole house RCD's shut off the whole house power when they
> trip?

Apart from older installations, no.

> If so, that sounds like it might be awfully inconvenient at best and
> possible dangerous if they should trip at night and leave the
> occupants stumbling around in the dark.

Not applicable...see abive.

> The point is...this allows the system to be selective about what to
> protect with a GFI. Generally, critical loads such as refrigerators,
> sump pumps, and fire pumps are never wired with GFI's to prevent
> nuisance tripping from current leakage caused by old wiring.

Exactly. Same here.

I have also installed battery backed lighting in critical areas; lights
can fail for other reasons than a trip (e.g. supply power failure).

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

dennis@home

2006-03-19, 11:21 am

tony sayer wrote:
>
>
> Odd that steel cored ally cable is use on the national grid at
> 400 kV!.....

That was a mistake that wont be repeated.

The prefered method is copper with a steel core to carry the weight.
It doesn't corrode as quickly as alu/steel.

dennis@home

2006-03-19, 11:21 am

The Natural Philosopher wrote:

> 48v 0Hz (DC)
>
> Since just about everything uses SMPS theses days - even lights - why
> have AC at all - and 48v is pretty much safer, especially DC.

Thats why I said 100V at 400Hz earlier.
You can make good SMPS with ferrite cores easily.

Bob Eager

2006-03-19, 11:21 am

On Sun, 19 Mar 2006 14:49:13 UTC, "dennis@home"
<dennis@killspam.kicks-XXX.net> wrote:

> The Natural Philosopher wrote:
>
>
> Thats why I said 100V at 400Hz earlier.

OK, apart from the transmission problem.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

dennis@home

2006-03-19, 11:21 am

Don Kelly wrote:
> ----------------------------
> "dennis@home" <dennis@killspam.kicks-XXX.net> wrote in message
> news:j7_Sf.38034$wl.20986@text.news.blueyonder.co.uk...
>
> And how do you get 400Hz to a home or industry? It is inferior to
> either 50 or 60 Hz for transmission and distribution. It does have
> advantages in aircraft but that 's about it.
> As to 100V- worsens the situation.
>
> I hope that you are not serious.

--

Half serious.
Transmission wasn't mentioned only what power would be best for houses.
You can do some nice stuff if you have a higher frequency supply than
50/60hz.
Like controlling motors is easier, transformers are smaller, SMPS are
smaller.

I'm not convinced that it would be worse for distribution either, but you
probably want a ~2kV - 100V ferrite transformer near the home.

tony sayer

2006-03-19, 11:21 am

In article <441d6681.1502921@newsgroups.comcast.net>, Beachcomber
<not_real@xxx.yyy> writes
>On Sun, 19 Mar 2006 10:11:42 +0000, tony sayer <tony@bancom.co.uk>
>wrote:
>
>
>Do the UK whole house RCD's shut off the whole house power when they
>trip?
>
>If so, that sounds like it might be awfully inconvenient at best and
>possible dangerous if they should trip at night and leave the
>occupants stumbling around in the dark.
>

Well we've had them for the past 25 odd years in two separate houses and
they've only tripped twice, and that was due to immersion heater leakage
and a duff element on the electric cooker.

They have tripped Twice in anger between those times.

In some rented houses we have they've tripped three times twice because
of leakage and once due to accidental contact.

Not really a big problem is it?, and its never happened during the hours
of darkness BUT we have had power cuts during the hours of darkness and
remarkably we have survived those!......

>In the North American System, they are called GFI's (sometimes GFCI's)
>Ground Fault Circuit Interrupters and standard practice is to place
>them on individual branch circuits (15 or 20 A) as combo GFI/circuit
>breakers or as stand alone units that are also duplex outlets. The
>latter may be wired to protect other downstream devices. There is a
>special, very expensive, GFI that must be used for hot tub
>installations.
>
>The point is...this allows the system to be selective about what to
>protect with a GFI. Generally, critical loads such as refrigerators,
>sump pumps, and fire pumps are never wired with GFI's to prevent
>nuisance tripping from current leakage caused by old wiring.

If old wiring is causing tripping, then the old wiring should become new
wiring ASAP....

--
Tony Sayer

Andrew Gabriel

2006-03-19, 11:21 am

In article <441d6681.1502921@newsgroups.comcast.net>,
not_real@xxx.yyy (Beachcomber) writes:
>
> Do the UK whole house RCD's shut off the whole house power when they
> trip?

RCDs have more than one type of use in the UK. An RCD which shuts
off the the whole house power should be >= 100mA trip current, and
is usually time-delayed. They are not for protecting against
electrocution, but against high earth fault loop impedance.

RCDs which protect against electrocution (<=30mA trip) are not
permitted to shut off a whole house. You will find some cases
where it's done though, which predate the current regs.

> If so, that sounds like it might be awfully inconvenient at best and
> possible dangerous if they should trip at night and leave the
> occupants stumbling around in the dark.

That's exactly why it's not permitted. Deaths from slips, trips
falls, etc in the home are 3 orders of magnitude higher than
deaths due to electrocution. It's considered bad practice to RCD
project lighting circuits in the UK (we use separate circuits for
lighting and power outlets, unlike you).

> In the North American System, they are called GFI's (sometimes GFCI's)
> Ground Fault Circuit Interrupters and standard practice is to place
> them on individual branch circuits (15 or 20 A) as combo GFI/circuit
> breakers or as stand alone units that are also duplex outlets. The

This is what I and a number of DIYers do. However, it's not what
you'll get an electrician do who's working to a budget. Combo RCD
and breakers are called RCBO's.

> latter may be wired to protect other downstream devices. There is a
> special, very expensive, GFI that must be used for hot tub
> installations.

I'm not very sure exactly what you mean by hot tub. We have hot
tubs in the UK, but I'm far from sure it means the same thing.
However, fixed apparatus designed for use in bathrooms has to be
safe without the use of an RCD in the UK. You can fit an RCD, but
it's not required.

> The point is...this allows the system to be selective about what to
> protect with a GFI. Generally, critical loads such as refrigerators,
> sump pumps, and fire pumps are never wired with GFI's to prevent
> nuisance tripping from current leakage caused by old wiring. The
> trip point on these standard devices is set at 5 ma and is normally
> not adjustable.
>
> Other outlets and devices are required by the code to be wired with a
> GFI including bathroom and kitchen outlets, plus outdoor and garage
> receptacles. There is a new rule that bedroom outlets must be wired
> with arc-fault protectors.

We don't permit any outlets or portable appliances in bath/shower rooms,
except for sockets with isolating transformers built in for shavers.
(Apparently, we have the lowest figure for bath/shower room electrocutions
per capita anywhere in the world.) Outlets in a bedroom which contains a
shower must be RCD protected and they have to be some considerable
distance from the shower. All outdoor outlets and other outlets which
might be used to power outdoor portable appliances must be RCD protected
at <= 30mA. That's pretty much it for the regulatory requirements
(ignoring rare cases and ignoring usage of RCD for purposes other than
protection against electrocution).

However, nowadays most socket outlets for portable appliances will be RCD
protected. Socket outlets intended for fixed and stationary appliances
don't merit RCD protection, so things like fridge/freezers, washing
machines, heating, etc are often provided from non-RCD protected circuits.
Lighting, as I said before, is always provided from a non-RCD circuit.

Arc-fault protectors are particular to the US market. Arcing is not
a serious issue anywhere else that I know, due to much higher quality
wiring accessories, lower current (because of higher voltage), and
hence significantly reduced tendency for connections to go bad in the
first place.

--
Andrew Gabriel

Andy Hall

2006-03-19, 12:21 pm

On Sun, 19 Mar 2006 14:29:36 GMT, not_real@xxx.yyy (Beachcomber)
wrote:

>On Sun, 19 Mar 2006 10:11:42 +0000, tony sayer <tony@bancom.co.uk>
>wrote:
>
>
>Do the UK whole house RCD's shut off the whole house power when they
>trip?
>
>If so, that sounds like it might be awfully inconvenient at best and
>possible dangerous if they should trip at night and leave the
>occupants stumbling around in the dark.
>

No. conventional practice is to organise the consumer unit with some
magnetic circuit breakers immediately after the incoming main circuit
breaker. These are used for lighting and other critical circuits.
There is then a 30mA RCD followed by MCBs for remaining circuits such
as those that could be potentially used to feed portable equipment
outside.

Alternatively, but not commonly, RCBOs are used - one per circuit.
These effectively combine MCB and RCD functionality.

Another approach is that individual wall outlets can have an RCD built
in to them.

--

..andy

meow2222@care2.com

2006-03-19, 12:21 pm

Beachcomber wrote:

>
> You said later in your post and I quote "110v is closer to the ideal
> efficacy voltage for house bulbs" so that is at least one reason for
> having the lower voltage. Not all the world has gone over to compact
> fluorescents and there are some applications where they might be
> downright undesirable.

I think its more an advantage than a reason. 12v makes for more
efficiency again, but really filament lamps arent the way forward
anyway.

> The North American Codes specify that no point on the kitchen counter
> should be less than 3 ft. from an outlet. In my small modest 15 x 15
> kitchen I count no less than 9 duplex outlets (18 outlets total).
> Our codes are concerned with safety, not convenience, but in this
> case, the idea is not to be plugging toasters and other high current
> appliance into extension cords.

Yes, we dont have that requirement here, but I still dont see any
extension leads in kitchens. Appliances with 3' leads would be a right
pain though!

> You can't even buy a toaster in the
> US anymore with a cord longer than 3 feet. Ever see those movies
> from the thirties were the appliances were plugged into the pendant
> socket hanging from the ceiling? Apparently, that was real bad...

A fair few houses were still like that in the 70s here, and I
volunteered in a workplace in the 80s still wired like that. How it
escaped the safety inspectors eyes I'm not sure, but evidently it had.
It had twisted pair cotton flex strung across the ceiling.

> I will conceed that those ring main circuits do allow you to power
> that 7.2 kW deep fryer though.... Something we can't do without extra
> effort.

that would be a big fryer! They dont fwliw, the point of 7.2kW is to be
able to run a large number of appliances rather than one bigun. There
is usually a lot more total load than 7.2kW on a ring, with diversity
and short term versus long term ratings all making it work. Our rings
are a much misunderstood system. I'm not going to add up what I've got
on the kitchen circuit but its well over 7.2kW.

> The most bizarre Euro power setup I ever saw was in the apartment I
> rented in Paris about 10 years ago. That French "Disjouncter" or
> whatever they call it would ration the power to the point where I
> could not have my water heater working if certain other routine loads
> where online at the same time. This was true even though the total
> load was much less than the installed capacity. They just didn't want
> you to be using too much power.

> It reminded me of the episode of the American TV Series Green Acres
> called "You can't plug in a 6 with a 2". Farmer Douglas tried to
> explain to his wife Lisa that all the power cords for the kitchen
> appliances had numbers on them corresponding to the size and current
> consumption of the device. If you went over 7, the generator outside
> the farm would start on fire.

Yes, familiar stuff. Thankfully we dont have to live like that these
days

> I stand by my original statement. We don't have many people in the US
> that say, "Gee it's only 120 volts... I don't respect it". Some...
> but not many.

check out Joe Tedesco's forum.

> 120 volts is safer than 220V. just as 220V is safer than 480V.

Do you have figures? I dont for the US. But I do know far more deaths
are the result of fire than electrocution, and 240 is demonstrably
better in that department.

> The same could be said for some of the UK practices from what I've
> read.
>
> Whether it's 120V or 240V, the N.A. codes say that we don't put these
> voltages in the shower. We don't even go near 240 volts in the
> bathroom. Other than lighting and a bathroom heater, there is only
> one allowed a GFCI protected outlet by the sink for a shaver or hair
> dryer. Some homes have electric outlets by the toilet. That is if
> you have one of those fancy TOTO models that sprays warm water up your
> arse.

We seem to have very different approaches to achieving bathroom safety.

NT

meow2222@care2.com

2006-03-19, 12:21 pm

tony sayer wrote:
>
>
> Odd that steel cored ally cable is use on the national grid at
> 400 kV!.....

Nothing odd about it, its lower cost. The joints are fully under the
control of a large power co that can ensure appropriate types of joints
are used, can measure line R and R fluctuation etc, and can maintain as
needed. But as already said, it has proven to be not such a hot idea.

Copper coated ali cable has also been tried, I was offered some in the
80s for commercial work. I cant think why that wouldnt work, but its so
rare it must have its problems too.

NT

Beachcomber

2006-03-19, 2:21 pm

On 19 Mar 2006 15:13:31 GMT, andrew@cucumber.demon.co.uk (Andrew
Gabriel) wrote:

>In article <441d6681.1502921@newsgroups.comcast.net>,
> not_real@xxx.yyy (Beachcomber) writes:
>
>RCDs have more than one type of use in the UK. An RCD which shuts
>off the the whole house power should be >= 100mA trip current, and
>is usually time-delayed. They are not for protecting against
>electrocution, but against high earth fault loop impedance.

So if I understand this correctly... If you have a direct short of the
hot wire to the earth connection... and the earth connection is of
high impedance for whatever reason and does not permit sufficient
current to trip the overload breaker... the RCD will sense that the
fault current is over 100 mA and trip after a time delay... Is that
right?

>
>RCDs which protect against electrocution (<=30mA trip) are not
>permitted to shut off a whole house. You will find some cases
>where it's done though, which predate the current regs.
>
>
>That's exactly why it's not permitted. Deaths from slips, trips
>falls, etc in the home are 3 orders of magnitude higher than
>deaths due to electrocution. It's considered bad practice to RCD
>project lighting circuits in the UK (we use separate circuits for
>lighting and power outlets, unlike you).
>
>
>This is what I and a number of DIYers do. However, it's not what
>you'll get an electrician do who's working to a budget. Combo RCD
>and breakers are called RCBO's.

Are you saying that the whole house RCD is the minimum permitted and
that additional RCD's are optional, at the discretion of the
electrician?
>
>
>I'm not very sure exactly what you mean by hot tub. We have hot
>tubs in the UK, but I'm far from sure it means the same thing.
>However, fixed apparatus designed for use in bathrooms has to be
>safe without the use of an RCD in the UK. You can fit an RCD, but
>it's not required.

Sorry.. I'm not always sure what is and what isn't American lingo

I believe hot tubs are also called spas. In the US, it's generally
an oversize tub mounted indoors or outdoors where the water is heated
to about 101 F. It contains jet pumps and filtration pumps,
ozonators, etc. The water is normally left in the tub, partially
heated and filtered when the tub is not in use. In California and
the west, Redwood hot tubs are popular.

There are also Jaccuzi's and Whirlpool baths which are generally
regular or oversize bathtubs that have pressure jets and heaters, but
are designed to be drained after use.

Because of all the electricity in close proximity to naked, wet
people, special GFI's are required. A popular model is made by
Seimens.
>
>
>We don't permit any outlets or portable appliances in bath/shower rooms,
>except for sockets with isolating transformers built in for shavers.
>(Apparently, we have the lowest figure for bath/shower room electrocutions
>per capita anywhere in the world.) Outlets in a bedroom which contains a
>shower must be RCD protected and they have to be some considerable
>distance from the shower. All outdoor outlets and other outlets which
>might be used to power outdoor portable appliances must be RCD protected
>at <= 30mA. That's pretty much it for the regulatory requirements
>(ignoring rare cases and ignoring usage of RCD for purposes other than
>protection against electrocution).
>
>However, nowadays most socket outlets for portable appliances will be RCD
>protected. Socket outlets intended for fixed and stationary appliances
>don't merit RCD protection, so things like fridge/freezers, washing
>machines, heating, etc are often provided from non-RCD protected circuits.
>Lighting, as I said before, is always provided from a non-RCD circuit.
>
>Arc-fault protectors are particular to the US market. Arcing is not
>a serious issue anywhere else that I know, due to much higher quality
>wiring accessories, lower current (because of higher voltage), and
>hence significantly reduced tendency for connections to go bad in the
>first place.
>
Just my opinion... Arcing is not a big problem in the US as far as I
know, either. I believe that during a certain year, there were just
one or two instances of a fire being caused in a bedroom because the
plug somehow got smashed by a bedframe. Despite the greater odds of
winning bigtime in a lottery than dying from an arc fault fire, the US
Code authorities decided to require arc fault protectors for bedroom
circuits, just in case.

That is one less outlet that I can plug my Tesla coil into.

I
hate it when the do that.

Beachcomber

raden

2006-03-19, 2:21 pm

In message <p2oBxv4k6KHEFw1v@ntlworld.com>, raden <raden@kateda.org>
writes
>In message <c52Tf.33$uY2.650@news.uswest.net>, SQLit <sqlit@qwest.net>
>writes
>It's all to do with currants raisin the heat
>
Can you believe that someone actually sent me a serious reply to that
post ?

--
geoff

sQuick

2006-03-19, 4:21 pm

"Owain" <owain47125@stirlingcity.coo.uk> wrote in message
news:1142780087.17582.1@eunomia.uk.clara.net...
> Beachcomber wrote:
>
> But because you use radial circuits with unfused plugs, you have to have
> limits on the number of sockets on a circuit, and thus a large number of
> circuits.
>
> We can have unlimited sockets on a 32A ring (or radial) circuit, subject
> to floor area and anticipated load. Our Wiring Regulations don't specify
> the minutiae of where to put sockets on a kitchen counter; that's left to
> the designer to ensure the installation is adequate.
>
> Of course, the superiority of the British ring circuit is another topic
> altogether.
>
>
> Same here; the requirement for flexible cords to be short enough that a a
> 20A breaker provides adequate fault protection is thanks to European
> unfused plugs.
>
>
> Actually, we can't either. Individual appliances are limited to 13A (the
> fused plug rating).

Not true, I've installed a fryer that took 25A. You can get 13A,16A & 32A
240v plugs & sockets.

sQuick..

dennis@home

2006-03-19, 4:21 pm

raden wrote:
> In message <p2oBxv4k6KHEFw1v@ntlworld.com>, raden <raden@kateda.org>
> writes
> Can you believe that someone actually sent me a serious reply to that
> post ?

cinnamon?

Chip

2006-03-19, 5:21 pm

On 18 Mar 2006 12:13:35 -0800,it is alleged that "Nehmo"
<nehmo54@hotmail.com> spake thusly in uk.d-i-y:

>For residential electrical use, there are two basic voltage & AC
>frequency systems across the world, http://kropla.com/electric2.htm.
>Does one have an advantage over the other? In other words, if you were
>starting from scratch and could impose a world standard, what would you
>choose?
>
>What voltage and what frequency?

As others have noted, it's been done to death already, but 110/120v
centre tapped [55-60v to earth] has advantages on safety grounds for
portable appliances.

--
You cannot shake hands with a clenched fist.
- Indira Gandhi

Andy Dingley

2006-03-19, 7:21 pm

On Sun, 19 Mar 2006 08:28:06 -0500, "sanjian" <millerkb@vt.edu> wrote:

>Except that, for the same function, AC motors are smaller, lighter, and
>cheaper. Which means you're unlikely to see DC in use.

How many AC motors do you have at home? Mine are almost all (barring my
big woodworking machines) universal motors. Even the old shaded-pole
motors in clocks and timers have gone digital now.

It's still a terrible idea though. Switching tens of DC amps isn't that
easy.

Andy Dingley

2006-03-19, 7:21 pm

On Sun, 19 Mar 2006 10:44:10 +0000, tony sayer <tony@bancom.co.uk>
wrote:

>Wonder why such a high voltage, its not that transmission losses will be
>all that great ?....

Keeps the current low, which simplifies simple DC switchgear.

If you really want to run kW domestic appliances from 48V DC, you'd be
looking at solid state switches instead of cheap mechanical ones.

Tony Williams

2006-03-19, 8:21 pm

In article <pMn59GE6XTHEFwG9@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:

> In article <4e0a000d56tonyw@ledelec.demon.co.uk>, Tony XXXXXXXX
> <tonyw@ledelec.demon.co.uk> writes
[color=darkred]
> Wonder why such a high voltage, its not that transmission losses
> will be all that great ?....

Avionics is very safety conscious, so it tends to
evolve rather than innovate. 115V 3-phase alternators
are already in service, so the only significant mod
is just a rectifier stack.

--
Tony XXXXXXXX.

Andrew Gabriel

2006-03-19, 9:21 pm

In article <441d8e38.2752796@newsgroups.comcast.net>,
not_real@xxx.yyy (Beachcomber) writes:
> On 19 Mar 2006 15:13:31 GMT, andrew@cucumber.demon.co.uk (Andrew
> Gabriel) wrote:
>
>
> So if I understand this correctly... If you have a direct short of the
> hot wire to the earth connection... and the earth connection is of
> high impedance for whatever reason and does not permit sufficient
> current to trip the overload breaker... the RCD will sense that the
> fault current is over 100 mA and trip after a time delay... Is that
> right?

Yes, although it's not simply a matter of tripping the breaker,
but tripping it within the required time (0.4 seconds for circuits
with socket outlets, 5 seconds for other circuits).

>
> Are you saying that the whole house RCD is the minimum permitted and
> that additional RCD's are optional, at the discretion of the
> electrician?

No. Whole house RCD is not permitted (except >=100mA as described
above, and only when really required). I described which circuits
are required to be RCD protected (at <=30mA to protect against
electrocution), and which ones are also commonly RCD protected
although not a regulatory requirement. If you ask an electrician
to do the job to budget as would normally be the case, you'll
get all the circuits which are RCD protected sharing the same RCD.
If I do the job myself, I use separate RCDs (or RCBOs) for each
of those circuits.

For example, here are the circuits from my consumer unit (panel),
together with the RCD trip ratings for the RCBO protected circuits:
6A Ground Floor lighting
6A First Floor lighting (which is second floor in the US;-)
6A Outdoor lighting
16A Water heater (only used in emergencies if gas boiler fails)
20A 30mA Attic sockets, bathroom and shower room wall heaters.
20A 10mA Outdoor sockets
20A Non-RCD protected sockets (fridge, freezer, heating control, etc)
32A 30mA Sockets in Kitchen
32A 30mA Originally the stove (now gas). Now oven, dishwasher, and kettle.
32A 30mA Sockets in rest of house.

This is a considerably better system than you would normally find
in a UK house. Since I was doing this myself rather than paying an
electrician, I could put the extra money into a better system.
The systems you would normally find are as described by Owain.

--
Andrew Gabriel

Paul Hovnanian P.E.

2006-03-20, 12:21 am

"dennis@home" wrote:
>
> Don Kelly wrote:
>
> Half serious.
> Transmission wasn't mentioned only what power would be best for houses.
> You can do some nice stuff if you have a higher frequency supply than
> 50/60hz.
> Like controlling motors is easier, transformers are smaller, SMPS are
> smaller.

The 800Hz hum from a transformer core or motor sounds real nice, too.
Not.

> I'm not convinced that it would be worse for distribution either, but you
> probably want a ~2kV - 100V ferrite transformer near the home.

Either 50 or 60 Hz is fine. But I'd like to see 480V 3ph in a house. 3
phase, of whatever voltage or frequency will do more for motor
efficiency than the other factors.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
APL is a write-only language. I can write programs in APL, but I
can't read any of them.
-- Roy Keir

sanjian

2006-03-20, 12:21 am

Andy Dingley wrote:
> On Sun, 19 Mar 2006 08:28:06 -0500, "sanjian" <millerkb@vt.edu> wrote:
>
>
> How many AC motors do you have at home? Mine are almost all (barring
> my big woodworking machines) universal motors. Even the old
> shaded-pole motors in clocks and timers have gone digital now.

Sometimes I forget that normal people have no need for the types of motors
I'm used to. Since I'm mainly concentrating on industrial construction
right now, my mind kind of kept going with everything I'm familiar with.

meow2222@care2.com

2006-03-20, 1:21 am

The Natural Philosopher wrote:

> 48v 0Hz (DC)
>
> Since just about everything uses SMPS theses days - even lights - why
> have AC at all - and 48v is pretty much safer, especially DC.
>
> The consumer unity has a 200A bridge rectifier and a bank of capacitors
> in it, and a power factor correction inductor. :D
>
> No nasty interference either.

Truth is that lots of kit still uses transformers.

Also I thought the question was what would one do starting around year
1900, and 48vdc would have been a difficult voltage for much of the
century.

Andy Dingley:

>It's still a terrible idea though. Switching tens of DC amps isn't that
easy.

Last time I switched >100A dc I used 2 copper washers. The extra
complications over ac are not major, as long as its low v.

NT

meow2222@care2.com

2006-03-20, 1:21 am

SQLit wrote:

> Please provide documentation for "230v standard does have significantly
> lower fire risk".

I read up on this in detail a while back, might have started from the
wiki ACFI page. In brief, higher v means both lower run current and
higher fault current, producing very much better fault discrimination
and fault clearance. There is also the lesser point that some faults
dissipate less heat on higher v.

NT

Bob Ferapples

2006-03-20, 4:21 am

Guy King

2006-03-20, 5:21 am

The message <6fns129r1f4pikmvfe89a9s014uhktlsn7@4ax.com>
from Bob Ferapples <licku45@yqahoo.com> contains these words:

> There is no place on the planet that does not already have electric
> service in some form or another,

Really?

--
Skipweasel
Pay no attention to the man behind the curtain.

tony sayer

2006-03-20, 6:21 am

In article <k2nr12hnt0e7iedjq1lj624n0da4riect6@4ax.com>, Andy Dingley
<dingbat@codesmiths.com> writes
>On Sun, 19 Mar 2006 10:44:10 +0000, tony sayer <tony@bancom.co.uk>
>wrote:
>
>
>Keeps the current low, which simplifies simple DC switchgear.
>

So they have 270 odd volt lamps then?.

And the Avionics and instrumentation all 270 or is there a lot of step
down switch mode?...

>If you really want to run kW domestic appliances from 48V DC, you'd be
>looking at solid state switches instead of cheap mechanical ones.

I don't think anyone would.....
--
Tony Sayer

The Natural Philosopher

2006-03-20, 7:21 am

sanjian wrote:
> The Natural Philosopher wrote:
>
> Except that, for the same function, AC motors are smaller, lighter, and
> cheaper. Which means you're unlikely to see DC in use.
>
>
Not sure they are actually.

Anyway, you can make a three phase inverter for AC motors to run on DC
fairly cheaply.

My real point was that with the advances in semiconductors, making AC
from DC and voltage transformation is not really a huge issue as it was
in the 20's when all the grid went in.

The Natural Philosopher

2006-03-20, 7:21 am

dennis@home wrote:
> The Natural Philosopher wrote:
>
>
> Thats why I said 100V at 400Hz earlier.
> You can make good SMPS with ferrite cores easily.
>
>
>
>
Yeah but they switch at a few Khz anyway, so what you feed them from is
irrelevant.

They all transform to DC at some point first...

The Natural Philosopher

2006-03-20, 7:21 am

dennis@home wrote:
> tony sayer wrote:
>
> That was a mistake that wont be repeated.
>

I don't think it is either a mistake, or not still carrying on.

> The prefered method is copper with a steel core to carry the weight.
> It doesn't corrode as quickly as alu/steel.
>

Al does not corrode markedly in air except near the coast.
>

David Hansen

2006-03-20, 1:21 pm

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On Mon, 20 Mar 2006 10:41:10 +0000 someone who may be The Natural
Philosopher <a@b.c> wrote this:-

>Anyway, you can make a three phase inverter for AC motors to run on DC
>fairly cheaply.

They are standard equipment.

--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

raden

2006-03-20, 4:21 pm

In message <441E240B.ED0895EA@Hovnanian.com>, Paul Hovnanian P.E.
<Paul@Hovnanian.com> writes
>"dennis@home" wrote:
>
>The 800Hz hum from a transformer core or motor sounds real nice, too.
>Not.
>
>
>Either 50 or 60 Hz is fine. But I'd like to see 480V 3ph in a house. 3
>phase, of whatever voltage or frequency will do more for motor
>efficiency than the other factors.
>
And how dangerous would that be in the wrong hands ?

--
geoff

Spokesman

2006-03-20, 9:21 pm

"Owain" <owain47125@stirlingcity.coo.uk> wrote in message
news:1142767577.13600.1@doris.uk.clara.net...
> Beachcomber wrote:
>
> The Germans wire 3-phase into heavy appliances - like instant showers in
> bathrooms.
>
>
> The British system has the advantage that we don't need separate circuits.
>
>
> Yes, but you still can't use a decent kettle in the bedroom.

We usually find other, more exiting, uses for the bedroom.

>
>
> Yes, it's because 50V has a safety advantage over both 110 and 240V. 50V
> is *Extra* low voltage. Anyway, 50-0-50V pre-dates RCDs and isn't
> actually necessary now, although most sites still insist on it.
>
>
> A lot of things are considered safe in North America that aren't here,
> like wire nuts and sockets in bathrooms.
>
> Owain
>
>
>

Don Kelly

2006-03-20, 11:21 pm

----------------------------
"dennis@home" <dennis@killspam.kicks-XXX.net> wrote in message
news:j7_Sf.38034$wl.20986@text.news.blueyonder.co.uk...
> Nehmo wrote:
>
> 400hz 100V -------

Why? What advantage?
400Hz is useful for aircraft because of weight/volume/power considerations
but these don't apply. Also 400Hz in home would require frequency converters
(extra $$$) as distribution is not particularly practical at this frequency
in comparison to 60Hz or below.
As for 100V, again why? What gain is made?

The proper answer to the original question is "it depends"
--

Don Kelly @shawcross.ca
remove the X to answer

Don Kelly

2006-03-21, 12:21 am

----------------------------
"Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote in message
news:441E240B.ED0895EA@Hovnanian.com...
> "dennis@home" wrote:
>
> The 800Hz hum from a transformer core or motor sounds real nice, too.
> Not.
>
>
> Either 50 or 60 Hz is fine. But I'd like to see 480V 3ph in a house. 3
> phase, of whatever voltage or frequency will do more for motor
> efficiency than the other factors.
>
> --
> Paul Hovnanian mailto:Paul@Hovnanian.com
> ------------------------------------------------------------------
> APL is a write-only language. I can write programs in APL, but I
> can't read any of them.
> -- Roy Keir

Agreed-partially. While 400Hz requires less iron in a motor, the problem
is that, for the speeds of typical household motors, we are looking at much
higher synchronous speeds- many more poles. Possibly a large diameter
pancake or simply use "brushless DC". Same control problem with that as with
a 60Hz supply. Transmission at 400Hz has its problems anywhere where
distances are large or L and C are appreciable. so that at local
substations there would have to be frequency converter stations- not cheap.
May as well go half-way and go DC for less$$.

Now, 480V, 3 phase, sounds good at either 50 or 60Hz.
--
C'mon now, APL isn't that bad to read unless you want to show off with
recursive one-liners! At least one can concentrate on the problem rather
than the code.
--

Don Kelly @shawcross.ca
remove the X to answer

Don Kelly

2006-03-21, 12:21 am

----------------------------
"The Natural Philosopher" <a@b.c> wrote in message
news:1142851337.14874.3@echo.uk.clara.net...[color=darkred]
> dennis@home wrote:
>
> I don't think it is either a mistake, or not still carrying on.
>
>
> Al does not corrode markedly in air except near the coast.
Aluminum cable, steel reinforced, replaced copper in the 1940's, and copper,
with or without a steel core, simply doesn't compete in terms of weight and
cost for a given current capacity. It's choice, around the world was not a
mistake, but a deliberate decision based on economics and performance.

Aluminum creep has been a problem with domestic wiring but not with
transmission system wires where proper attention (and expense) is paid to
splices and connectors.

--

Don Kelly @shawcross.ca
remove the X to answer

dennis@home

2006-03-21, 9:21 am

"Owain" <owain47125@stirlingcity.coo.uk> wrote in message
news:1142943967.24544.2@iris.uk.clara.net...
> Spokesman wrote:
>
> Yeah, but us Brits like a nice cuppa tea afterwards

After.
You need a good cuppa after the first three or four hours to get your
strength back for the rest of the night.

Bud--

2006-03-21, 12:21 pm

Owain wrote:
> Jim Michaels wrote:
>
>
>
> There is; I don't know whether in the actual NEC but there certainly are
> in many local regulations.
>

The NEC has no limit on the number of outlets per circuit for
residential. It specifies the number of circuits and the distance
between the outlets and a competent installer will distribute the
outlets between circuits. Local regulations can modify any part of the
code in any way making discussions a bit difficult.

For non-dwelling, in general, an outlet (single or dupex) is figured to
be 180VA, or 10 max on a 15A circuit.

bud--

Andy Dingley

2006-03-21, 8:21 pm

On 19 Mar 2006 20:19:19 -0800, meow2222@care2.com wrote:

>Andy Dingley:
>
>easy.
>
>Last time I switched >100A dc I used 2 copper washers. The extra
>complications over ac are not major, as long as its low v.

Now do it repeatedly. DC is hard to switch because the arc isn't
self-quenching (when the AC drops to zero). For DC you have to have a
mechanical separation that's far and fast enough to extinguihs the arc,
and contacts resistant enough to survive the wear of this intervening
period.

David Hansen

2006-03-21, 8:21 pm

On Tue, 21 Mar 2006 23:41:57 +0000 someone who may be Andy Dingley
<dingbat@codesmiths.com> wrote this:-

>Now do it repeatedly. DC is hard to switch because the arc isn't
>self-quenching (when the AC drops to zero). For DC you have to have a
>mechanical separation that's far and fast enough to extinguihs the arc,
>and contacts resistant enough to survive the wear of this intervening
>period.

Indeed. DC switchgear isn't bulky because the manufacturers are
especially ripping buyers off, but because DC is difficult to switch
off. If it was otherwise then the switches one sees in buildings
wouldn't be marked "AC only".

--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

The Natural Philosopher

2006-03-21, 9:21 pm

Andy Dingley wrote:
> On 19 Mar 2006 20:19:19 -0800, meow2222@care2.com wrote:
>
>
> Now do it repeatedly. DC is hard to switch because the arc isn't
> self-quenching (when the AC drops to zero). For DC you have to have a
> mechanical separation that's far and fast enough to extinguihs the arc,
> and contacts resistant enough to survive the wear of this intervening
> period.
>
Its real problem. Its why the commutators and brushes of DC motors last
about 30 seconds and no DC motors are made that run over 5A or 50 RPM ;-)

Its that switching of high current DC that does it.

My car starter motor solenoid can barely manage 5 starts at 400A 12v DC
before I need a new one.

That's why all modern cars run on 400V 10kHz AC.

The Natural Philosopher

2006-03-21, 9:21 pm

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David Hansen wrote:
> On Tue, 21 Mar 2006 23:41:57 +0000 someone who may be Andy Dingley
> <dingbat@codesmiths.com> wrote this:-
>
>
> Indeed. DC switchgear isn't bulky because the manufacturers are
> especially ripping buyers off, but because DC is difficult to switch
> off. If it was otherwise then the switches one sees in buildings
> wouldn't be marked "AC only".
>
>
Is there something in the water?

Sure, 400V DC will sustain an arc better than 400V AC, but its HARDLY a
huge problem to design a switch that will handle 40V DC at 75A?

meow2222@care2.com

2006-03-21, 10:21 pm

The Natural Philosopher wrote:
> David Hansen wrote:
[color=darkred]
> Is there something in the water?
>
> Sure, 400V DC will sustain an arc better than 400V AC, but its HARDLY a
> huge problem to design a switch that will handle 40V DC at 75A?

I gotta agree with you on that one. A dc switch requires faster
opening, larger contgact separation and bulkier contacts. But none of
these are in any way difficult to do!

Ac switches are made dc-inadequate because slow opening performs better
on ac, and smaller contacts are 0.1p cheaper.

NT

Andy Dingley

2006-03-21, 11:21 pm

On Mon, 20 Mar 2006 09:25:58 +0000, tony sayer <tony@bancom.co.uk>
wrote:

>And the Avionics and instrumentation all 270 or is there a lot of step
>down switch mode?...

Aircraft have gone through several generations of power supply,

First of all there were engines with magneto ignition and no power to
the instruments.

By WW2 a 12V DC battery system was common, with an engine powered
generator. Towards the end of WW2 this was generally upgraded to a 24V
battery and 28V DC busbar system fed by variable speed generators and
regulators. These ranged from about 0.5kW to 12kW power.

AC began as low-power 400Hz 3 phase or 1600Hz single phase systems to
drive instrumentation and position-sensing synchros. This was "derived"
power, supplied by DC-powered rotary inverters with inbuilt speed
control.

Larger multi-engine aircraft demanded more power for radar, windscreen
and crew suit heating, bomb releases, etc. and so the voltage increased
to keep the current and the wiring manageable. These were 112V DC busbar
systems, driven by a number of DC generators, one per engine. These were
variable speed, voltage regulated and might offer about 20kW of power.

A 28V DC system was maintained to power the standard instrumentation
developed in earlier low-voltage systems. This was fed by a rotary
inverter.

High electric power for de-icing heating, gun turret traverse or the
beginnings of high power systems like landing gear lowering or even
flight controls gave a demand for even more power. This needed a more
efficient, simpler and lighter generator and so there was a switch to AC
generation. These were simple variable speed (and so variable frequency)
208V AC devices for de-icing (by far the biggest electrical load), or
104V outputs that were then rectified and fed to the 112V DC busbar
system.

The 400Hz and 1600Hz instrumentation supplies continued, supplied by DC
rotary inverters.

With the development of constant speed drives to the generators, it was
practical to maintain a constant frequency, and to synchronise
generators between engines. This was the beginning of 400Hz 3 phase as
the standard high power supply in aircraft, at 200V and up to around
20kW. The 112V DC systems disappeared, but the 28V DC busbar was
retained for compatibility, powering the low-power equipment. This was
driven by its own constant-speed DC generator and was also battery
backed up, maintaining radios and flight instruments in emergency.

All-AC aircraft appeared when specialist DC equipment no longer needed a
common busbar but could provide its own DC "in cabinet". A 28V DC busbar
was retained, but just to provide emergency battery backup.

Don Kelly

2006-03-22, 1:21 am

"The Natural Philosopher" <a@b.c> wrote in message
news:1142988159.95762.0@demeter.uk.clara.net...
> Andy Dingley wrote:
> Its real problem. Its why the commutators and brushes of DC motors last
> about 30 seconds and no DC motors are made that run over 5A or 50 RPM ;-)
>
> Its that switching of high current DC that does it.
----------------------
I assume that what you are saying is tongue in cheek.

As for the switching of high current DC in a DC motor, please note that the
whole rotor winding is not switched so the voltage across the coil being
switched is small(ideally 0) and the brushes short this coil at the time,
making a controlled reversal of current in this single coil. Sometimes
things aren't perfect and at heavy currents rather nasty arcing can occur.
There is also a reason why brushes are made of carbon. DC motors are fine
but are also high maintenance devices compared to AC machines.

However one can get switches for 48VDC, 25A or 100A. Not a problem but
expensive compared to AC switches. For household use- there is no point in
going to DC. --

Don Kelly @shawcross.ca
remove the X to answer
----------------------------

>
> My car starter motor solenoid can barely manage 5 starts at 400A 12v DC
> before I need a new one.
>
> That's why all modern cars run on 400V 10kHz AC.

Don Kelly

2006-03-22, 1:21 am

Remember the old switches which could handle DC?. A 15A switch was somewhat
bigger than the present AC switch but had a bloody good spring which was
essential in quickly opening up a gap sufficient to extiguish the arc. This
was noisy, subjest to failure and comparatively hard to operate. AC switches
depend on the arc becoming unstable at the current zero and don't need this
cumbersome mechanism.
It's not that slower opening performs better on AC but it can be tolerated
as the switch doesn't have to force a current zero and the arc is likely
extinguished just as quickly as with the old switches.
--

Don Kelly @shawcross.ca
remove the X to answer
----------------------------
<meow2222@care2.com> wrote in message
news:1142990361.814265.268130@v46g2000cwv.googlegroups.com...
> The Natural Philosopher wrote:
>
>
> I gotta agree with you on that one. A dc switch requires faster
> opening, larger contgact separation and bulkier contacts. But none of
> these are in any way difficult to do!
>
> Ac switches are made dc-inadequate because slow opening performs better
> on ac, and smaller contacts are 0.1p cheaper.
>
>
> NT
>

Member, Takoma Park Volunteer Fire Department

2006-03-22, 2:21 am

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David Hansen wrote:
> On Tue, 21 Mar 2006 23:41:57 +0000 someone who may be Andy Dingley
> <dingbat@codesmiths.com> wrote this:-
>
>
>
>
> Indeed. DC switchgear isn't bulky because the manufacturers are
> especially ripping buyers off, but because DC is difficult to switch
> off. If it was otherwise then the switches one sees in buildings
> wouldn't be marked "AC only".
>
>
I had a hard time convincing one foreman that we could not use AC only
snap switches on the emergency lighting circuits in an older building we
were remodeling. As soon as I saw that the emergency lighting panels
were single phase 208/120 supplied by locking AC coil contacters I
looked around for the battery room. There in all their ancient glory
were 120 two volt wet cells wired in series that the contacters dropped
out to when the AC power fails. Those batteries had the emergency
lighting Grounded Current Carrying Conductors tapped of between
batteries 60 and 61 which was also the ground reference for the DC
supply. It was a true Edison circuit. All of the emergency lights were
incandescent. All of the existing switches had a large T stamped into
the strap. The T indicates that the switch can safely close on the
inrush current of it's rated load in tungsten filaments. That mark is
only found on specification grade DC switches. Later in that same
project some brilliant soul decided to use up some left over unit
battery pack exit lights as replacements for the old two bulb
incandescent fixtures. The first time the power failed the power
supplies for the unit battery chargers all burned up when the 120 volt
DC hit the transformers. The contractor then sold the customer on the
necessity of upgrading to inverter supplied AC for the emergency
lighting circuits. The batteries were regrouped into three 48 volt
banks to supply three inverters that were interconnected so as to supply
208/120 volt AC.
--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

Andrew Gabriel

2006-03-22, 5:21 am

In article <ff3122tr3vai3hvderhm8pi0vimt6u0emh@4ax.com>,
Andy Dingley <dingbat@codesmiths.com> writes:
>
> Aircraft have gone through several generations of power supply,

Very intesting, thanks for that.

The first computer company I worked for manufacturered a lot of
equipment for air force and navy. We had whopping great 400Hz
generators outdoors to power the military stuff, but I don't
now recall the voltage it supplied. (Not sure why we used
generators rather than rotary converts -- might have been
cheaper to buy?) We also had a very hefty 52VDC supply for
equipment which went into telephone exchanges.

--
Andrew Gabriel

tony sayer

2006-03-22, 7:21 am

>All-AC aircraft appeared when specialist DC equipment no longer needed a
>common busbar but could provide its own DC "in cabinet". A 28V DC busbar
>was retained, but just to provide emergency battery backup.

Thanks for that, very interesting,

I wonder what the electricity bill for a Jumbo comes out at;-))
--
Tony Sayer

Tony Williams

2006-03-22, 8:21 am

In article <1NtudgHuySIEFwNU@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:

> I wonder what the electricity bill for a Jumbo comes out at;-))

An alternator assembly bolted to each engine, and
one on the auxiliary power unit (APU) in the tail.
Each alternator will probably be capable of over
100KVA. The alternators will be 2-pole, spinning
at 24000rpm. A 100KVA 400Hz alternator is not that
large, something like a very large starter motor.
Driving the alternator is the hydraulic constant
speed gearbox, with splined input shaft and bell
housing for attachment to the auxiliary take-off
point on the side of the engine.

That hydraulic constant speed gearbox has a large
power loss and a huge weight penalty for an aircraft,
which is the motive for the moves to variable
frequency aircraft mains, or to that 270Vdc bus
in recent helicopters.

--
Tony XXXXXXXX.

David Hansen

2006-03-22, 8:21 am

On 21 Mar 2006 17:19:21 -0800 someone who may be meow2222@care2.com
wrote this:-

>A dc switch requires faster
>opening, larger contgact separation and bulkier contacts.

Precisely.

>But none of these are in any way difficult to do!

Nowhere did I claim that it is difficult to produce DC switchgear.
However, it is bulky compared to an AC only version. Certainly not
worthwhile installing in residential properties.

--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Derek ^

2006-03-22, 3:21 pm

On Sat, 18 Mar 2006 18:03:02 -0700, "SQLit" <sqlit@qwest.net> wrote:

>
>Please provide documentation for "230v standard does have significantly
>lower fire risk".
>

Well in the UK the body which writes the standards for electrical
appliances including cables , flexes, plugs and sockets is the
"British Standards Instiution".

http://www.bsi-global.com/News/Information/index.xalter

"BSI British Standards is the National Standards Body of the UK and
develops standards and standardization solutions to meet the needs of
business and society. They work with government, businesses and
consumers to represent UK interests and facilitate the production of
British, European and international standards."

In the US it is the UL, "Underwriters Laboratories". The Laboratories
of the Fire Insurance Companies.

Reading a few UL standards quickly reveals that their primary concern
is that electrical appliances don't start fires. ISTR that <such and
such> appliance must not release molten metal under any fault
condition.

That's what in the UK we don't get.

meow2222@care2.com

2006-03-22, 10:21 pm

Don Kelly wrote:
> Remember the old switches w