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Dave Plowman (Nutcase Moron) wrote:

------------------------------------



I'd expect anything to cope with a short term over voltage. But long term
may well be very different. Up to you if you want to risk it.

I have a Quad 405 on the bench at the moment. That has settings for
220,230 and 240v. Why would they bother if it didn't matter?


** Only matters so owners can get rated power output figure.

Very few other makers bother with such small corrections.


..... Phil

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"Mike Fleming" wrote in message
...
In article , "Dave Plowman (News)"
writes:

In article ,
Mike Fleming wrote:
In article , "Dave Plowman
(News)"
writes:

220v sounds very like a US etc standard.

Doesn't sound much like a US standard as their mains voltage is
around
half that.

They tend to have a higher voltage for things like electric cookers
and
heating, etc.

Hi-fi units would generally be run off common or garden mains rather
than the higher voltage (which IIRC is done by using opposite
phases,
so it's actually two 120V supplies in antiphase with a neutral which
is ignored to get 240V).


Well nearly. There is no such thing as antiphase on a three-phase
supply. You get (in the US) 120V between any single phase and earth
(which is connected to the star point) and 120(3e0.5) or about 208V
between phases - just as we have 240V single phase or 415V across two
phases in the UK, or 220V and 380V respectively in Europe.


--
Woody

harrogate3 at ntlworld dot com

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Woody wrote:



220v sounds very like a US etc standard.

Doesn't sound much like a US standard as their mains voltage is
around half that.

They tend to have a higher voltage for things like electric cookers
and heating, etc.

Hi-fi units would generally be run off common or garden mains rather
than the higher voltage (which IIRC is done by using opposite
phases,
so it's actually two 120V supplies in antiphase with a neutral which
is ignored to get 240V).


Well nearly.


** Exactly, really.

There is no such thing as antiphase on a three-phase
supply.


** But it is not, most premises in the USA have "2 phase" power.

240VAC is split by a transformer into a pair of 120VAC supplies with a common centre tap - usually grounded.

Ordinary appliances use the US flat pin 120V plugs while high current and permanently wired ones connect across the phases.




..... Phil

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In article ,
Phil Allison wrote:
Dave Plowman (Nutcase Moron) wrote:

------------------------------------



I'd expect anything to cope with a short term over voltage. But long term
may well be very different. Up to you if you want to risk it.

I have a Quad 405 on the bench at the moment. That has settings for
220,230 and 240v. Why would they bother if it didn't matter?


** Only matters so owners can get rated power output figure.

Very few other makers bother with such small corrections.


I remember seeing Quad 405s used with BBC monitor speakers with a label
added to all of them (Do not set to 230v - leave on 240) or somesuch,
after the 230v harmonisation. Presumably for a good reason. ;-)

--
*The hardness of the butter is proportional to the softness of the bread *

Dave Plowman London SW
To e-mail, change noise into sound.

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In article ,
Phil Allison wrote:
** But it is not, most premises in the USA have "2 phase" power.

240VAC is split by a transformer into a pair of 120VAC supplies with a
common centre tap - usually grounded.

Ordinary appliances use the US flat pin 120V plugs while high current
and permanently wired ones connect across the phases.

That isn't what's normally meant by phases.

If you go across two phases in the UK, you don't get double the single
phase voltage.

--
*Verbs HAS to agree with their subjects *

Dave Plowman London SW
To e-mail, change noise into sound.

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Dave Plowman wrote:

If you go across two phases in the UK, you don't get double the single
phase voltage.

Because our phases are 120° apart (all the way from generator to
premises that have 3-ph) but the way the USA phases are delivered
they're 180° apart (at least from the pole pig to the premises as 2-ph,
presumably they have 3-ph from generator to the street, with
transformers in general spread between the phases?)

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On Mon, 21 Aug 2017 11:14:29 +0100, "Dave Plowman (News)"
wrote:

In article ,
Phil Allison wrote:
Dave Plowman (Nutcase Moron) wrote:

------------------------------------



I'd expect anything to cope with a short term over voltage. But long term
may well be very different. Up to you if you want to risk it.

I have a Quad 405 on the bench at the moment. That has settings for
220,230 and 240v. Why would they bother if it didn't matter?


** Only matters so owners can get rated power output figure.

Very few other makers bother with such small corrections.


I remember seeing Quad 405s used with BBC monitor speakers with a label
added to all of them (Do not set to 230v - leave on 240) or somesuch,
after the 230v harmonisation. Presumably for a good reason. ;-)

I believe, and I'm sure someone will correct me if I'm wrong, the UK
spec is 230 V +10% -6%, so 253 V to 216 V.

Any time I've had occasion to measure it at home (Dundee) it's been
pushing the upper limit. A few minutes ago it was 248 V.

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On 21-08-17 14:38, John J Armstrong wrote:

I believe, and I'm sure someone will correct me if I'm wrong, the UK
spec is 230 V +10% -6%, so 253 V to 216 V.

Yes - it was a typical political compromise. UK is 230V +10%/-6%
(or 240V +6%/-10%) and Continental Europe 230V +6%/-10% (or 220V
+10%/-6%), so they get away saying both are nominally 230V...

Julf

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On Mon, 21 Aug 2017 11:39:45 +0100, Andy Burns
wrote:

Dave Plowman wrote:

If you go across two phases in the UK, you don't get double the single
phase voltage.

Because our phases are 120° apart (all the way from generator to
premises that have 3-ph) but the way the USA phases are delivered
they're 180° apart (at least from the pole pig to the premises as 2-ph,
presumably they have 3-ph from generator to the street, with
transformers in general spread between the phases?)

Three phase makes good sense. Local supply must be three phases plus a
neutral return, with as far as possible equal load on all phases. This
arrangement is called a star.

But trunk transmission doesn't require a neutral. The arrangement is
called delta and the neutral for each phase is a virtual one
comprising the vector sum of the other two phases. That's a big metal
saving, because a physical neutral would have to be three times the
area of a phase.

d

---
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https://www.avast.com/antivirus

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In article , Don Pearce
wrote:
On Mon, 21 Aug 2017 11:39:45 +0100, Andy Burns
wrote:

Dave Plowman wrote:

If you go across two phases in the UK, you don't get double the
single phase voltage.

Because our phases are 120° apart (all the way from generator to
premises that have 3-ph) but the way the USA phases are delivered
they're 180° apart (at least from the pole pig to the premises as
2-ph, presumably they have 3-ph from generator to the street, with
transformers in general spread between the phases?)

Three phase makes good sense. Local supply must be three phases plus a
neutral return, with as far as possible equal load on all phases. This
arrangement is called a star.

However my understanding of the USA is as Andy says. The power gets to the
street level as 220v. It is then split into two 110v supplies using a
center-tapped transformer. Each house may get a 220v and one of the 110v
volt feeds. I guess this is for some 'historic' reason. Having spent some
time in small Kansas town one of my old photos may show one of the
transformers on a pole that does this. Not looked, but I have to trawl them
for a webpage tomorrow so I may see if I can find an example.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html