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On Tue, 22 Aug 2017 16:55:39 +0100, Jim Lesurf
wrote:

In article , Johan Helsingius
wrote:
On 22-08-17 12:37, Dave Plowman (News) wrote:

So what are the nominal voltages - given everyone seems to say
different?

Maybe Wikipedia is clear enough:

"...
the nominal voltage at the source should be 120 V and allow a range of
114 V to 126 V (RMS) (-5% to +5%). Historically 110 V, 115 V and 117 V
have been used at different times and places in North America. Mains
power is sometimes spoken of as 110 V; however, 120 V is the nominal
voltage."

Maybe it is. However, clear or not, I've more than once found errors in
Wikipedia, so I'd regard it as a guide to what is probably correct rather
than a reference.

Maybe a bit more authoritative is the table published by the Pacific
Gas and Electric Company. Naturally it is more complicated than a
simple blanket tolerance.

Standard 120V
Service +/- 5% 114 to 126
Utilization -13% +6% 104.4 to 127.2
Nameplate Motor 115
NEMA +/- 10% 103.5 to 126.5


So the NEMA tolerance is taken from the Nameplate nominal of 115V.
Lots of new terms to look up, then.

d

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Maybe it is. However, clear or not, I've more than once found errors in
Wikipedia, so I'd regard it as a guide to what is probably correct rather
than a reference.

I agree. But usually Wikipedia also contains references to the
original sources (this is what the editors strive to). In this
case CENELEC Harmonisation Document HD 472 S1:1988, ANSI
C84.1 and BS 7697.

Julf

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On Mon, 21 Aug 2017 16:18:31 +0200, Johan Helsingius wrote:

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...


Absolutely spot on! It was simply a change in the regulations with
regard to the PSU's obligations to maintain end customer supply voltages
agreed between the UK and mainland Europe to allow the use of a 'notional
design voltage' for (essentially) domestic appliances (excluding tungsten
filament lamps which *do* need to be designed for the *actual* local
voltage used in the catchment area of the stores selling such lamps).

The advice note attached to those Quad 405s was simply a reminder that
the supply voltage would still remain 240v with very little danger of the
supply ever being matched to the notional 'Harmonised Supply Voltage' of
230v.

--
Johnny B Good

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In article ,
Johnny B Good wrote:
The advice note attached to those Quad 405s was simply a reminder that
the supply voltage would still remain 240v with very little danger of the
supply ever being matched to the notional 'Harmonised Supply Voltage' of
230v.

I don't know the history, but it seems it was the only bit of BBC
equipment marked thus. The inference being they didn't take kindly to
being set to 230v.

--
*Remember, no-one is listening until you fart.*

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

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On Wed, 23 Aug 2017 18:11:50 +0100, Dave Plowman (News) wrote:

In article ,
Johnny B Good wrote:
The advice note attached to those Quad 405s was simply a reminder that
the supply voltage would still remain 240v with very little danger of
the supply ever being matched to the notional 'Harmonised Supply
Voltage' of 230v.

I don't know the history, but it seems it was the only bit of BBC
equipment marked thus. The inference being they didn't take kindly to
being set to 230v.

One possibility might be Quad Acoustical taking advantage of the tighter
voltage tolerance required (for whatever reason) to save transformer
materials costs otherwise demanded by a "Universal" higher primary
voltage design supplying a voltage agnostic circuit (voltage regulators
and/or final output stage) in the form of extra iron and copper to keep
hysteresis losses at an acceptable level.

If you have to go to the trouble of closely matching a mains transformer
primary voltage to the supply voltage due to other considerations such
meeting a maximum output power for a given acceptable level of
distortion, you might as well extract the full benefit of minimising
transformer costs whilst you are at it. (i.e. Don't miss a trick! :-)

--
Johnny B Good

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In article ,
Johnny B Good wrote:
On Wed, 23 Aug 2017 18:11:50 +0100, Dave Plowman (News) wrote:

In article ,
Johnny B Good wrote:
The advice note attached to those Quad 405s was simply a reminder
that the supply voltage would still remain 240v with very little
danger of the supply ever being matched to the notional 'Harmonised
Supply Voltage' of 230v.

I don't know the history, but it seems it was the only bit of BBC
equipment marked thus. The inference being they didn't take kindly to
being set to 230v.

One possibility might be Quad Acoustical taking advantage of the
tighter voltage tolerance required (for whatever reason) to save
transformer materials costs otherwise demanded by a "Universal" higher
primary voltage design supplying a voltage agnostic circuit (voltage
regulators and/or final output stage) in the form of extra iron and
copper to keep hysteresis losses at an acceptable level.

If you have to go to the trouble of closely matching a mains
transformer primary voltage to the supply voltage due to other
considerations such meeting a maximum output power for a given
acceptable level of distortion, you might as well extract the full
benefit of minimising transformer costs whilst you are at it. (i.e.
Don't miss a trick! :-)

The other possibility - it was the BBC active crossover fitted inside, and
powered from the same PS. A weird and wonderful device.

--
*If at first you don't succeed, avoid skydiving.*

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

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Johnny B Good wrote:

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


The advice note attached to those Quad 405s was simply a reminder that
the supply voltage would still remain 240v with very little danger of
the supply ever being matched to the notional 'Harmonised Supply
Voltage' of 230v.

I don't know the history, but it seems it was the only bit of BBC
equipment marked thus. The inference being they didn't take kindly to
being set to 230v.

One possibility might be Quad Acoustical taking advantage of the tighter
voltage tolerance required (for whatever reason) to save transformer
materials costs otherwise demanded by a "Universal" higher primary
voltage design supplying a voltage agnostic circuit (voltage regulators
and/or final output stage) in the form of extra iron and copper to keep
hysteresis losses at an acceptable level.

If you have to go to the trouble of closely matching a mains transformer
primary voltage to the supply voltage due to other considerations such
meeting a maximum output power for a given acceptable level of
distortion, you might as well extract the full benefit of minimising
transformer costs whilst you are at it. (i.e. Don't miss a trick! :-)


** The Quad 405 and 405-2 were designed to accommodate a +/- 10% variation from the set voltage without change in performance - says so in the 405-2 manual.

However, the set voltage needs to match the typical incoming supply voltage for this to work out.

Quad 405s are *not* unusually sensitive to supply voltage.


..... Phil