House wiring and transformer voltage regulation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Hydrogen18" <hydrogen18-at-bellsouth-dot-net> 

Although I have never done precise measurements per say let me say this. I
have a pc running in my room, with 3 monitors on it(current unknown) along
with 2-3 100 watt bulbs. If I plug in a hairdryer it drops voltage so far my
UPS kicks(I remember testing it with a variac and remembering that it cut in
at 110 volts).

I know shunts are used in welders to limit current, and the constant current
charateristics they provide are desirable. In terms of voltage regulation,
how does a transformer limited with a series inductor limiting current
differ from one with internal shunts(poor coupling)?

---Eric
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, August 03, 2004 8:04 AM
Subject: Re: Dr R's 16KV 300ma transformer


 > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >
 > On 2 Aug 2004, at 18:11, Tesla list wrote:
 >
 >  > Original poster: "Hydrogen18" <hydrogen18-at-bellsouth-dot-net>
 >  >
 >  > The 1600 watts isnt going to heat, it is magnetizing the core.
 >
 > I never said it was going to heat, somebody else did. I assumed (!)
 > that you were actually meaning VA.
 >
 >  > I thought the voltage drop relative to current draw was intrinsic to a
 >  > transformer. My mains voltage drops when current draw increases.
 >
 > By how much? (rhetorical question). Mind you, if it drops
 > significantly (Like more than a couple of volts or so) it might be an
 > indication of underrated wiring or the hint of some fault being
 > present. No transformer is lossless but unless they are specifically
 > designed to have poor regulation, they are usually pretty good.
 >
 > Malcolm
 >
 >
 >
 >  > ---Eric
 >  > ----- Original Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Monday, August 02, 2004 8:07 AM
 >  > Subject: Re: Dr R's 16KV 300ma transformer
 >  >
 >  >
 >  >  > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >  >  >
 >  >  > On 1 Aug 2004, at 19:15, Tesla list wrote:
 >  >  >
 >  >  >  > Original poster: "Hydrogen18" <hydrogen18-at-bellsouth-dot-net>
 >  >  >  >
 >  >  >  > I guess shunted transformers can be done right(although the only
 >  >  other >  > kind I can think of are welders, which dont really matter
 >  >  much as long >  > as they burn well). But with my 4 pack I have a
 >  >  HUGE magnetizing >  > current(1600 watts!). I guess part can
 >  >  attributed to bad power factor >  > and the fact that the cores are
 >  >  running at 70000+ lines of flux per sq >  > inch. But why dont all
 >  >  transformers have shunts? I know the winding >  > over winding method
 >  >  prevents the use of them, but I'm sure shunts >  > could save more
 >  >  than one small transformer which was accidentally >  > shorted/wired
 >  >  wrong/etc. > > Time for a bit of basic transformer theory perhaps.
 >  >  The reason most > transformers don't have shunts is because it would
 >  >  degrade their > regulation. NSTs and other current limited
 >  >  transformers are designed > to have poor regulation so that they
 >  >  don't deliver an unlimited load > current with a short circuit parked
 >  >  across the output. You can > imagine the mayhem that would be caused
 >  >  by shunted distribution > transformers - as soon as someone turned on
 >  >  a heater, the lights > would dim. The winding-over-winding method
 >  >  ensures that the coupling > between the primary and secondary is as
 >  >  high as possible given > insulation requirements. > >       Shunts
 >  >  *do not* prevent core saturation. Using enough pole area > so that
 >  >  the flux density is kept within the ratings of the core > material
 >  >  does. Any transformer which has an excessively high > magnetizing
 >  >  current flowing in its primary either doesn't have enough > pole area
 >  >  for the core material used or has too high a voltage > applied to it.
 >  >  > > Malcolm > > >
 >  >
 >  >
 >