Preowned Units
 

Dave Plowman ****ing Nutcase wrote:

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

** Where has the context gone ???

Dave snipped it all so he could invent a new one.



** 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.


** Dave missed the parentheses I use around the term.


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


** So ****ing what?



...... Phil

Preowned Units
 

Andy Burns 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?)


** Distribution is via 3-phase, like anywhere else.


...... Phil

Preowned Units
 

Don Pearce wrote:

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


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.


** In a 3-phase plus neutral supply, the max neutral current possible is when only one phase is loaded. Adding in a second phase reduces the neutral current and loading all three equally reduces it to zero.

The one exception to this is if all the loads use rectifier and capacitor PSUs without PFC. Then it is possible for all the current pulses to combine in the neutral without overlap - producing 3 times the heating effect of one phase current.

The above could never arise in a 3-phase trunk supply.


..... Phil

Preowned Units
 

In article ,
Phil Allison wrote:
Dave Plowman ****ing Nutcase wrote:

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

** Where has the context gone ???

Dave snipped it all so he could invent a new one.



** 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.


** Dave missed the parentheses I use around the term.

Parenthesis doesn't excuse using the wrong term - especially from a pedant
like you.

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


** So ****ing what?

A reason to use the correct term?



..... Phil

--
*I love cats...they taste just like chicken.

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

Preowned Units
 

In article ,
Huge wrote:
On 2017-08-21, Jim Lesurf wrote:

[19 lines snipped]

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.

Correct. (My parents have lived in the USA for 35 years and in recent
years I have worked on their house. Wire nuts are very scary.)

I guess this is for some 'historic' reason.

Large domestic appliances draw too much current on 110V supplies.
Combined with aluminium ("aluminum") wiring, wooden houses, volunteer
fire brigades and long distances, this is an incendiary combination.
Can't imagine that wire nuts help.

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

If a transformer, 110 and 220v?

--
*White with a hint of M42*

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

Preowned Units
 

On Tue, 22 Aug 2017 11:37:50 +0100, "Dave Plowman (News)"
wrote:

In article ,
Huge wrote:
On 2017-08-21, Jim Lesurf wrote:

[19 lines snipped]

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.

Correct. (My parents have lived in the USA for 35 years and in recent
years I have worked on their house. Wire nuts are very scary.)

I guess this is for some 'historic' reason.

Large domestic appliances draw too much current on 110V supplies.
Combined with aluminium ("aluminum") wiring, wooden houses, volunteer
fire brigades and long distances, this is an incendiary combination.
Can't imagine that wire nuts help.

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

If a transformer, 110 and 220v?

120/240 I believe is the nominal. But the geography of the country
means that many rural people are on the end of long lines. I'm sure
they use transformers with adjustable taps to get the voltage as close
as possible, but I reckon it's a bit of a lottery as to what you
actually get.

d

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Preowned Units
 

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:

"Following voltage harmonisation, electricity supplies within the
European Union are now nominally 230 V ±10% at 50 Hz.[6] For a
transition period (1995–2008), countries that had previously used
220 V changed to a narrower asymmetric tolerance range of 230 V
+6%/−10% and those (like the UK) that had previously used 240 V
changed to 230 V +10%/−6%. No change in voltage is required by
either system as both 220 V and 240 V fall within the lower 230 V
tolerance bands (230 V ±10%). Some areas of the UK still have 250
volts for legacy reasons, but these also fall within the 10%
tolerance band of 230 volts. In practice, this allows countries
to continue to supply the same voltage (220 or 240 V), at least
until existing supply transformers are replaced. Equipment (with
the exception of filament bulbs) used in these countries is
designed to accept any voltage within the specified range. In the
United States and Canada, national standards specify that 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."

Preowned Units
 

In article , Dave Plowman (News)
wrote:

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

If a transformer, 110 and 220v?

My recollection is that it was 110 and 220 where I visited. But it was
decades ago so my memory may well be faulty. Wasn't the purpose of my
trip(s) to the USA! 8-]

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

Preowned Units
 

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.

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

Preowned Units
 

Dave Plowman ****ing Nutcase wrote:

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

** Where has the context gone ???

Dave snipped it all so he could invent a new one.



** 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.


** Dave missed the parentheses I use around the term.

Parenthesis doesn't excuse using the wrong term


** My usage of the term was 100% correct - you ****ing moron.




..... Phil