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Re: Figure this out.
In a message dated 97-01-22 03:41:24 EST, you write:
> ANY time we Coilers use a Neon
> Transformer we are Gamblin' with the Odds because of that Case Center Tap
> Problem. It is the Single Greatest Cause of Grief and Frustration, because
> just when you think you've got the Perfect Neon... ZAP! Your Neon's Fried!
I have come to the conclusion after using many types of transformers from
many different manufacturers that the problem is not one so much of centertap
grounding as it is with hot spots and corona that form wihin and between the
windings of the neon secondary. The first transformer that I ever used I
still have and it still works flawlessly (its a 15kv 60ma.) The reason is
that early on I removed it from its case and melted the tar off by soaking it
a week in paint thinner. I then built a plexigalss case for it which I then
filled with synthetic refridgeration compressor oil (which has excelent
dielectric strenght and cooling properties). I have run a medium sized coil
with that transformer flat out (3to 4 ft arcs with minimal terminal
capacitance and a 4"diam by 18" high secondary) continuously for 15 to 20
minutes at a time for a total of nearly *20 hours* of operation both with and
without saftey chokes and *without* a saftey gap.
The reason that I orriginally repotted the transformer in oil is that early
on (after about an hour total of operation) I began to hear a "buzzing" noise
eminate from the trans and saw the output begin to deminish (the beginning of
a short, I suspect). After repotting in oil, the buzzing went away and the
outpur returned to its former intensity and has remained so ever since....
Excelent emperical evidence about what a good dielecrtic cooling medium can
do for a stressed coil.
I have also recently begun work on smaller coils and have found (after
destroying several of them after just a few minutes of operation) that a
company called "newtown" here in Illinois produces an open core and coil line
that uses a specially potted secondary winding that is vacuum imregnated with
epoxy. These are the only transformers that I have been able to run
continuously without breakdown so far (about two hours total). Because of
the vacuum impregnation of the secondary, there are no air bubles in the
epoxy which acts as an excelent insulator and also as a good conductor of
heet away from the secondary (much as an oil bath would).
The removal of heet and the improvement of dielecrtic strenght between the
windings is, from my point of view, *the* key to reliable neon transformer
operation in tesla coil service.
By the way, the newtown open core transformers are vastly superior in
construction to most of the other transformers that I have used and examined.
The fit, finish, and overall design and manufacturing precision is
exceptional, better than even France transformers which were my previous
favorite, they are also half the price!!! The newtown open cores also
employ a totally floating secondary (not grounded to the core) for thoes who
are interested. Newtown will be the company that I will pruchase all of my
future open core transformers from and I would recommend them highly.
Other thoughts welcomed.
-DavidF-