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Re: Ballasting a Pole Pig (Revisited)



Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>



You can get rid of the "thump" on variacs by using 0.450 Ohms of resistance in series with your
current limiting inductor.

The water resistor is a clever idea though!!!

Dr. Resonance




Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Let me share with you what *I* do, though it's
probably going to make some people point and laugh :)

Though it's terribly lossy, the ballast I presently
use for my TC and Jacob's ladder is just a 20 gallon
plastic garbage can filled with water that's been
doped with several table spoons of baking soda (add to
taste! :D )  Submerged in the can are two copper
pipes, about 6' long each, oriented vertically, with
about 3/16" space between them.  One of the pipes has
a piece of PVC over it.  Raising and lowering the PVC
varies the resistance smoothly from several hundred
ohms down to about five ohms (depends on the water
level and amount of doping, of course).  A PVC "T"
connector with another short length of PVC tube
creates a nice control handle.  Everything needed
(except the baking soda and water) can be found at
Home Depot for around $30.

I like it.

Again, I know it's terribly lossy, however it does
seem to work ok, and can run for quite a while before
the water begins steaming.  Also, operation is nice
and smooth; no big "thump!" noises when things are
brought up, and hence, I suspect, a bit less stress on
transformer insulation.  Down the road, I'll be
experimenting with a hybrid inductive/resistive
ballast, but for now, wholly-resistive does what I
need :)

To contrast with a similar ballast design that I heard
mentioned long ago, wherein the electrodes are
*lowered into* the water, the design above has the
following advantages (IMO):

1) Because the PVC shield is raised to reduce the
resistance, gravity is naturally working to *increase*
the resistance, which means that if you drop the
handle or something else breaks, the power is probably
going to be reduced automatically instead of the other
way around.  Definitely a good thing!

2) Because conduction starts at the bottom of the
garbage can, convection improves circulation of the
water, thereby permitting you to run the thing for
longer.  If you were to lower electrodes into the
water, conduction would begin at the top, and that's
where the heat would tend to stay; it would tend to
heat very rapidly!

I suppose electrolysis effects produce some H and O
while the thing is running, however from the bubbling
I see, I don't think the volumes of gas produced are
sufficient (particularly in my relatively
well-ventilated garage) to create an explosive
atmosphere.  At least I *hope* not!!

aaron


--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "C. Sibley" <a37chevy@xxxxxxxxx>
>
> David,
>
> I only have a 15A 220V circuit to play with, and am
> in
> the process of getting the electrical upgraded.  I
> can
> run the setup for longer periods with the welder set
> to a lower current.  But at the lower currents the
> voltage to the pig is essentially zero.  I have
> verified and cleaned all of the hookups.
>
> I'll try one of the other ballast methods and let
> the
> list know what I find.
>
> Curt.
>
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
>  > Original poster: "David Rieben"
>  > <drieben@xxxxxxxxxxxxxxx>
>  >
>  > Curt,
>  >
>  > It sounds almos

msnip...