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Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>
In a message dated 5/30/01 12:04:32 PM Eastern Daylight Time,
> I am facing that thorny issue when using a pole transformer and that is
> ballast. I have read that one can ballast a pole transformer with a
> rated variac configured as a variable inductor. I have also read that this
> method is not ideal because the variac core does not have an air gap and is
> thus liable to saturate. Also, since the maximum number of variac wire
> may not be used, this does not fully utilize all of the core. I have read
> other people use this method and it works fine. I have also read that
> constant-current arc welder is an ideal ballast. If so, how is it
> the secondary left open or shorted? I assume that the pole transformer
> drawn through the arc welder primary in a series connection. Facts, not
> conjecture, would be greatly appreciated.
Many folks have had excellent results using a welder as a ballast.
The secondary is shorted, and yes, the welder primary is used in
series with the pig primary. It is also true that a variac is best used
with a slot cut in the core. Some folks said they had good results
using a variac without a slot, but when I tried it, the system drew
double the current compared with my other (homemade) ballast.
This may be because I was only able to use a few of the variac
turns as you suggested.
Some folks also like to add some resistive ballast, perhaps
a couple of ohms in series or parallel with the welder to smooth
out the operation. Other folks have found no difference either way.
Much depends on the break-rate, capacitor size, sync or non-sync