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Re: Ballast ?



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Rich,

Are you sure the transformer doesnt have any builtin ballast. You can verify this using a variac driving the transfomer with secondary shorted. Start low on the output voltage of the variac and plot current vs voltage to see if it is as expected. If the slope is correct then take it up to where the transformer primary current is 150ma * turns ratio. If you get full 240Vac at this current level, the transformer is already ballasted. Just start out low and slow until you feel comfortable going to a higher voltage.

Gerry R

Original poster: "Rich & DJ" <rdj@xxxxxxxxxxxx>

Hi Gerry , it is junk as a NST , I had to remove a few windings on one
side to get continuity but the other side took half the windings to get
a reading so its scrap unless I use the primary core for a ballast , I
don't know all the electrical rules but here is a roll of 10ga wire with
an iron core , not much different from a roll of wire from home depot
with welding rods in it.
I need ballast on 240v, I have a transformer that requires 240v primary
, secondary is 13Kv, no MA listing on the tag but it is 1.95Kva so that
come in about 150ma. It should be about 8amps of 240v and all will be
OK.
 I need a way to control the current if I use it with a Tesla Coil. I
don't want to run a resistor as a ballast. I did test the transformer
with some high wattage 240v quartz bulbs as a ballast and made a Jacobs
ladder but I read an inductive ballast is better. It is all trial and
error at this end but I hope I only see sparks out of the coil and not
the power supply.

Rich , from the middle of Missouri

Subject: Re: Ballast?

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Rich,

The ballast use probably wont work on 240 since the NST was designed
for 120 in terms of core satuation.  Two in series might work
depending on what current you are after.  You might try to melt the
tar in an oven.  Often this will reflow any carbon tracking and
restore the NST (assuming that is what's wrong).  Also, you could
remove the tar and guts, clean it up, find what's wrong with it and
fix it, and then make a case to emerse it into oil (no more fragile NST.

Gerry R.

>Original poster: "Rich & DJ" <rdj@xxxxxxxxxxxx>
>
>I have a Jefferson/Magnetek transformer, 15Kv 60ma, 120v primary..
>The secondary is bad,  it has some nice 10ga wire for the primary.
>  Would it be possible to use just the primary as a ballast on 240v
> , with out the secondary?
>This unit has no removable shunts for adjustment that I can see.
>
>Rich
>
>