Re: Pole transformer ballast

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

Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bigfoo39-at-telocity-dot-com>

Tesla list wrote:

> Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<slwhite-at-zeus.ia-dot-net>
>
> I am thinking of using an arc welder as a pole pig ballast. The cheaper
welders
> (e.g. Lincoln AC-225)  that I have seen appear to use a multi-tapped
secondary
> with resistive current limiting on the primary. If so, then I question
whether
> using one of these would be much better than simple resistive current
limiting.
> The more expensive welders appear to use a crank mechanism to move the
primary
> and secondary of the transformer with repsect to each other. This seems much
> more desirable as no resistive current limiting is involved. Does anyone know
> for certain which welders use the movable transformer core method? I
think that
> Miller and Century do this but I am not sure. This entire ballasting issue is
> proving to be my most perplexing problem.

Hi Steve...

inductive ballasting was also my nemisis...  I spent months learning and
trying and frying things
before I came up with a working ballast.  Welders can be used as ballast
BUT you must take into
consideration that the current supplying the pig will be going thru the
primary of the welder... if
you make extended runs on this type of setup, the primary of the welder
will become quite hot and
meltdown. If you read the manual of the welder, they talk of something
called a duty cycle...  time
on and time off  ( in other words... you NEED to let the primary of the
welder cool off)  most
welders are rated at the secondary side for amps  if you see a welder rated
for 225 amps thats the
secondary side output, not the input side. The input side is probably rated
for 40 - 55 amps MAX
with a 1:10 duty cycle.  If you cant find any really big EI cores to
rewind, then look for welders
with copper wire on the primary side ( #10 or thicker). Also look for the
sliding style shunt bar
that lies between the primary and secondary ( for current adjustment).
Since you have mentioned
that this is intended for piggie use... make efforts to find the largest
core possible. Small to
medium sized cores will saturate around 20 - 30 amps depending upon the
number of windings on the
core. This will result in run away current and a fried variac along with
some blown fuses  ( but
the streamers are really great looking for about 1 second)   if you wish
... take a look at the
pictures at  HTTP://members.telocity-dot-com/~bigfoo39/  under Tesla coils and
under pics of the BIGPIG
coil. There you will see an inductor that works well ( up to 80 or so amps
with the piggie)


Scot D