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Re: using an SS White x-ray transformer

Hi John,
    Reverse one of the windings and you have 45 kV at 14 mA.  I
unpotted two neon sign transformers.  I soaked their coils in toluene
and then ethanol to remove the hydrocarbon residue.  I then laid them
on a teflon sheet, to prevent sticking, and applied a coat of red
glyptol, available at electronic parts companies.  The gluptol soaked
through and formed a barrier that allowed the entire winding to be
filled with the stuff without leaking.  I baked it at about 150
degrees F for about a week until it got hard.  Then I peeled it off of
the teflon sheet.  I put it back on the core and surrounded it with
teflon sheets.  It has performed well for many years.   I haven't
assembled the 15 kV, 60mA transformer yet.

    I have an x-ray transformer also.  When I remove it I will soak it
in mineral oil to remove the old oil and then change out to fresh
mineral oil.  Above 20 kv I would recommend oil unless you want to pot
the windings in high thermal conductivity high voltage epoxy.  At the
higher voltages the insulation gets so thick that thermal problems
become great.  Oil solves these problems.

    Several times, I have had to refill the oil in a + - 100 kV, 300
mA, Maxwell power supply after I fixed it (I was having too much
fun!).  I followed Maxwell's procedures.  They said to let the
transformers sit in the oil for a few hours (a few days would be
better if you have the time).  Next, bring the voltage up to 10 kv and
let it buzz for about an hour.  Next, bring the voltage up to 20 kv
and let it buzz for about an hour (more of a massive humm-buzz sound).
This procedure is continued until full voltage is achieved.  I only
went up to 80 kv as I only used the transformer up to 70 kv.  It
worked fine.  The combination of the core vibration and the heat
worked the air out nicely.

Barry

----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, August 19, 1999 4:56 AM
Subject: using an SS White x-ray transformer


> Original Poster: "John" <jbowers1-at-jnlk-dot-com>
>
> Hello everyone, first time to post here.  Here's my situation:  I
have a 90 Kv,
> 7 mA transformer from an older 1978 SS White x-ray generator and I
want to
> readapt it for Tesla coil or other use.  With testing using a variac
and meter,
> I've found all the windings to be functioning properly.  Here's my
problem: The
> transformer was operated in transformer oil originally (which had
been drained
> out) and I've been told it is very difficult to remove all of the
air and
> moisture from the tyranny upon refilling without a vacuum pump and
jar.  Since
> I don't care to invest in the expensive equipment required for the
job, I'm
> wondering if I can operate this transformer at one half of its
output (50Kv, 3
> mA) either dry or just filling with mineral/ transformer oil (or
even kerosene)
> without vacuuming?  It was difficult to obtain this transformer and
I'd hate to
> burn it out, but I'm dying to experiment and I'm hesitant.  I
already know it's
> not current limited and that's one reason for the variac use.  Any
pointers
> would be appreciated.
>
> By the way, this transformer is set up kind of like a neon
transformer:  one
> leg has a maximum of positive 45 Kv-- the other leg negative 45 Kv.
>
> Thanks,
> John Bowers
>
>
>