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Re: Transformer Ballasting





---------- Forwarded message ----------
Date: Fri, 17 Oct 1997 01:54:42 -0500
From: "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Transformer Ballasting 

To: Gwyn

Try to scrounge the surplus yards or old theater groups to find a burned
out variac --the 30 amp variety has a good cross sectional area which is
the key ingredient.  Remove all the old windings.  Clamp the variac solidly
so it doesn't go "sprong" and carefully saw through with a fine hacksaw. 
In the gap epoxy a piece of plastic approx 0.100 inches thick (100 mils). 
Next hand wind the variac with 160 turns of #8 AWG insulated wire.  Tap at
150, 140, and 130 turns.  You now have a cheap and very good pole pig
current limiter -- save the welder for welding.  Use a 1/2 Ohm, 10 KW
resistor (about 12 feet of heater nichrome) in series with this limiter and
your coil will run even smoother --- eliminates the 100 kw peak surges.

DR.RESONANCE-at-next-wave-dot-net


----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Transformer Ballasting 
> Date: Thursday,October 16,1997 10:35 PM
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Thu, 16 Oct 1997 21:21:21 -0500
> From: Chuck Curran <ccurran-at-execpc-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Transformer Ballasting 
> 
> Hello Gwyn:
> 
> I would suggest you look at the method that has been used by quite a
number
> of the Coiler's who are using pole pigs or plate transformers.
> Specifically, a very effective method for limiting the short circuit
current
> is to place the primary side of a welder in series with the pole pig
> primary.  The result is a means of controlling your current draw, to the
> point where using the arc current adjustment system on your stick welder
> does a pretty decent job.  I would look for a welder with a rating around
> 225 amps output, if your intent is to work with higher power levels. 
When
> you do employ a welder, you must also take the welder output leads and
short
> them together.  I wouldn't be concerned with potential voltage drop.  The
> success of many of us with this technique pretty well proves it as a
> reasonable alternative.  You should also investigate using the inductance
> current limiting (welder) along with a auto-transformer to vary both the
> input current and the voltage.  I've always employed the auto-transformer
> to run things up slowly---I don't have anything big enough to hide under
to
> slam a new system with full line voltage right from the start!  :^)  Some
of
> the coiler's have also worked with hand wound inductors with different
taps
> for varying the current limiting, another possible solution.  The good
part
> about the welder is that it is fast and effective, with the bad part
being
> it will cost about $190.00.  Gee, mine is 18 months old now and it has
never
> welded!
> 
> Chuck
> 
> -----Original Message-----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
> Date: Thursday, October 16, 1997 4:21 PM
> Subject: Transformer Ballasting
> 
> 
> >
> >
> >---------- Forwarded message ----------
> >Date: Thu, 16 Oct 1997 19:43:35 +0100
> >From: Gwyn Zucca <gwyn-at-tcbod.demon.co.uk>
> >To: tesla-at-pupman-dot-com
> >Subject: Transformer Ballasting
> >
> >Hello All,
> >
> >I have tried searching the list archives for anything on the subject of
> >current limiting power transformers, but I did not find exactly what I
> >was looking for. The problem seems to be limiting the short out current
> >without reducing the output voltage of the transformer. Obviously any
> >resistance in circuit with the xfrm primary is going to develop a volt
> >drop across it, and so the primary voltage will be lower than the rated
> >output. The use of an inductive ballast, is going to have a similar
> >effect. I have been experimenting with various arrangements, but have
> >not yet achieved a satisfactory solution.
> >
> >Any thoughts, experiences on this subject would be welcome.
> >
> >See Ya...
> >
> >Gwyn
> >--
> >Gwyn Zucca
> >ng
> >