Variac for ballast

["Oxandale, Terry" <Toxandale-at-SPP-dot-org> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi all;
Just a quick note to let some of you in on my experience with using a
variac for ballast. Originally I have limited my current to the pole pig
using a large solenoid coil from an old distribution breaker. This
solenoid coil (I'll call it a reactor from now on) is about 7" in
diameter and about 6" tall with a center hole for the plunger that is 3"
in diameter. The coil is wound with 10 ga magnet wire and weights about
30lbs. With a all air core, this has never given me the smaller currents
I really needed, so I made a make-shift core using welding rods to keep
the eddy currents (and heat) down. With this core, and also tapping the
coil at several places I was able to get small (usable) currents for the
pig. Anyway, I decided to try the 28amp variac as the ballast one day,
and was never able to get a smooth operation from the tesla coil.
Instead the coil would pop and sputter until I had the reactance turned
down so low that I was burning up everything else in the circuit with
the high currents. I then returned to the original reactor (many more
windings and very little iron) and was able to run the coil very well.

Question: Was my problem due to the magnetizing inrush of current to set
the core of the variac? It seemed that I was using an abnormal amount of
current but the tank circuit of the coil  wasn't using it. It was almost
like the dwell time on the SG was just enough to magnetize the variac
core, but not long enough to get past this to be used by the
transformer. As soon as I went back to the other reactor, I didn't have
the full scale spike in the ammeter every time I energized the circuit,
and the coil operated fine at about 1/3 the amperage. If this is true,
would wider contacts on the RSG alleviate this problem?

Terry