Re: Cap-driven x-former?

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

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

Power factor correction on a small extra winding makes since. Suppose you
have a transformer that stays live on the line 24/7. Being a buisness you
get billed for bad power factor. To correct this the power company says
install capacitors along with the transformer(A calculated value). It might
as well be some random number, perhaps 342 uF. However, if the voltage was
perhaps 600 volts in stead of 240, it would be the value of an off the shelf
capacitor possibly. Some manufacturers incorporate this into the design of
their transformers.

---Eric
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, June 11, 2004 7:28 AM
Subject: Re: Cap-driven x-former?


 > Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net>
 >
 > Hi all,
 >
 > This bit of info my help
 >
 > Many years ago now I worked for a company that made power units for either
 > GE or GEC (I don't remember which). The power units were for a
photocopying
 > machine.
 >
 > My understanding was that they were constant voltage (stabilized)
 > transformers.  They had magnetic shunts and an extra secondary winding
that
 > was connected to a cap. The secondary voltage was about 4kV and they were
 > used directly and via  doublers/triplers to supply the high voltages
 > required for the charging and discharging wires of the photo drum.  They
 > were big transformers as big if not bigger than an MOT. Although  now I
know
 > that it is unlikely they needed anywhere near the power of a MOT.
Possibly
 > they needed low resistance for good regulation.  This was back in the days
 > when a serious copying machine was built like a tank and approaching the
 > size of a small car.
 >
 > One more point it was my understanding that they used the magnetic
 > saturation of the main core as the stabilization effect and the cap and
 > shunts improved the wave shape of the output. The shuts may also regulate
 > the input current as the core saturates.  I believe because of the core
 > saturation effect and hence higher losses  most constant voltage
transforms
 > are much larger than for a given VA rating than a regular transformer.
This
 > may also have been why the GE/GEC units were so big given their probable
VA
 > rating but I suspect it was also impart a very conservatively rated design
 > and  no strong pressure to be small or light weight.
 >
 > Does it make sense to perform PF correction on the secondary of a
 > transformer? Unusual if nothing else.
 >
 > Bob
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Monday, June 07, 2004 6:54 PM
 > Subject: Re: Cap-driven x-former?
 >
 >
 >  > Original poster: Jim Lux <jimlux-at-earthlink-dot-net>
 >  >
 >  > Check out:
 >  >
 >  > http://home.earthlink-dot-net/~jimlux/hv/xfmrex1.htm
 >  >
 >  > This is basically the same transformer. (GE part 9T68Y5021G10 )
 >  >
 >  > C&H Surplus has them as TR9407 for $50.
 >  >
 >
http://www.aaaim-dot-com/u/web/aaaimc/cgi-local/shop991/shop.pl/SID=2385848520/p
 > age=TRFS.htm#TR9407
 >  >
 >  > It works just fine without the capacitor (except for the power factor
 > being
 >  > terrible).
 >  >
 >  > There are several flavors of it that I've seen: a 220V version, a 50Hz
 >  > version, etc.
 >  >
 >  > Yours is a 5022G10, which is probably a somewhat different
configuration,
 >  > but fundamentally the same.
 >  >
 >  > FWIW, I don't know that GE ever made ferro-resonant transformers.
 >  >
 >  > I haven't been able to find out how it was used in the copiers.
 > Originally,
 >  > I thought it might be used to run an arc lamp, but the voltage is awful
 >  > high.  So, my latest guess is that it was used to charge a reservoir
cap
 > to
 >  > fire some very bright flash tubes. Kodak had some very fast
photocopiers
 >  > back in the late 70's early 80s that used a fairly large array of flash
 >  > tubes, and looking over old EG&G literature, I think I found the tubes
 > that
 >  > they used.
 >  >
 >  > At 06:28 PM 6/7/2004 -0600, you wrote:
 >  > >Original poster: "Jim Mitchell" <Electrontube-at-sbcglobal-dot-net>
 >  > >Well I'd think it was ferro-resonant, because he says the output is
 > horrible
 >  > >without the capacitor.  Google could tell more then I could,  as I
don't
 >  > >know much about the ferro-resonant circuit.
 >  > >
 >  > > >  >  >      More specs: Seller advertised it as out of a copier
power
 >  > >supply.
 >  > > >  > Inked
 >  > > >  >  > on the side of the unit is "General Electric part #
 > 9T68Y5022G10".
 >  > >Made
 >  > > >  > for
 >  > > >  >  > Eastman Kodak (with an Eastman Kodak part #).
 >  > > >  >  >      Cap is a 10uF 1000VDC oil-filled type.
 >  > > >  >  >
 >  >
 >  >
 >  >