Robert Bonomi wrote:

In article ,
Ulysses wrote:

"Me" wrote in message
...

In article ,
"Ulysses" wrote:


"wmbjk" wrote in message
m...

On Thu, 16 Jun 2005 15:43:10 GMT, "Pete C."
wrote:


Not necessarily. Home welding tends to be short duration. The hardware
to supply that kind of power is actually affordable, and if one is
designing the power system from scratch for what most would consider a
normal home, then the extra inverter capacity isn't a big deal. In our
case, for the house loads alone we could have gotten away with a
single SW4024 plus a transformer for the 220V loads.

How is this done, getting 220V from 110? How do you get the two "hot"
wires? Are there 2 secondary windings on the transformer? Wouldn't

they

need to be out of phase with each other?



Now here is a fellow that asks an inteligent question. If you take
a dual winding secondary with 120 Vac on each winding, feeding it
with a 120 Vac Primary, and connect the dual 120Vac windings in series
you get 240Vac. The phase is determined on how you connect the two
series windings. and they will either be inphase or 180 out of phase,
depending on the connection.

Me

Something else I've wondered about is why is it sometimes called 220, other
times 230, and also 240VAC? Do the different voltages imply single or
double phase or is it just a matter of different voltages in different
geographic locations? My little Honda generator is rated at 125 VAC which
seems to be unusual and that would give us 250 VAC if it was ran through the
step-up transformer.


It's a matter of history. The "standard" -- for what was expected at the
outlet in a residence -- changed over the years as power distribution got
better.

Circa WW II line voltage was 110VAC. by the mid 50's, this had climbed to
115VAC. by the early 60's, 117VAC. By the late 60', 120V. The 'two hots'
circuit was frequently called "220", even when the actual voltage was as high
as 235 (2x117). "240" does seem to have mostly displaced the old name.

Anyway, if somebody mentions a number in the 110-120 "or so" range, they're
talking about the same thing. Ditto for anything in the 220-240 range.
"208" is a "special" value. as is "277". Both having to do with specific
arrangements of 'three-phase' circuits.


Your Honda is probably at claimed 125V because of *lousy* voltage regulation.
125V at 'no load', dropping to 120V (or lower) as the load increases.



I've seen 125V used in high density housing - simply to lower the current in
the same wires.

Our house in the mountains of No. Ca. was a few miles from a swinging transformer.
Under low load, the transformer was at one voltage, as the current increased,
the transformer switched in another set of windings up until it hit an end.
The swinging transformer had massive make-before-break contacts that always rang
(voltage hits) as it moved. I called the power company when it started hitting
my lines heavy (I was logging them on my APC's) and they found a burnt contact.

So at one time or another, depending on load and speed of the swinger - it could
be many voltages.

Martin

--
Martin Eastburn
@ home at Lion's Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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