Re: new power transformer (variac as ballast)

In a message dated 98-08-28 19:24:56 EDT, you write:

<< << As opposed to welders, you can also use large variacs as the ballast for
 > potential and pole transformers.  Bill Wysock suggested that I replace my
 > welder with a variac when I was having problems with my system.  I was
 > to find a 5,000 watt light dimmer (Luxtrol D-5000B rated at 40 amps) and it
 > works great.  I use this with 3.2 ohms of resistance in series.  This is
 > now I can leave the welder at work where it belongs.
 > Ed Sonderman >>
 Did you have to cut a slot in the core to prevent saturation?  I've always
 heard this was necessary.  Does the TC draw basically the same amount 
 of current with the variac as with the welder?
 John Freau


I haven't cut a slot in it - I didn't want to ruin it for possible future use.
Maybe I should as I think it does saturate sometimes.  I am guessing by the
occasional bumps and humming that it does.  If it is rated at 40 amps, then it
should not saturate with less than that through it, correct?  Of course I am
running all the current through only about one half of it.  I am running 35 to
40 amps through the pole transformer primary - about the same as with the
welder.  Only now my safety gap across the caps does not fire.  Possibly I
eliminated a 60 hz resonance problem by replacing the welder.

Ed Sonderman