Re: RE- Secondary wire & insu

Subject:      Re: RE- Secondary wire & insu
       Date:  Thu, 12 Jun 1997 11:06:11 -0700
       From:  Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization: Greiner, Ltd.
         To:  Tesla List <tesla-at-pupman-dot-com>
 References:  1

Tesla List wrote:
> Subject:      Re: RE- Secondary wire & insu
>        Date:  Mon, 9 Jun 1997 09:42:03 +1200
>        From:  "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
> Organization: Wellington Polytechnic, NZ
>          To:  tesla-at-pupman-dot-com
> Re close-wound vs space-wound,
>                                There is actually not a huge
> difference between them. You can view a space wound coil as being a
> close wound coil wound with thinner wire. Spacewound has it all over
> closewound when it comes to well-bolstered turn-turn insulation, but
> as some recent experiments of mine show, voltage breakdown is
> probably the least of your worries in getting a good coil going.
> Consider: If the voltage is approaching that which will tax the wire
> insulation, the coil would be shooting sparks straight from top to
> bottom. IMO it is only because coils are typically run at voltages
> somewhat less than this limit that the streamers can reach out and
> grow to many times the "voltage length".
>     This last weekend I tried the now-bolstered 2.5" high litz coil
> on the minisystem I am playing with and the single shot length (low
> rep rate) exceeded the winding height - just. There was a faint
> corona visible on the outside of the coil varnish. Increasing coupling
> beyond that point made it shoot straight up and down with no hope of
> streamer growth.
> Malcolm

Hi Malcolm and All

I agree but only up to a point. As you know, I have a 24" high secondary
with only 192 turns of pvc insulated #16 machine tool wire. This coil
puts out in excess of 60" streamers. I have never had a turn to turn
insulation breakdown. There is no additional coating of any kind on the
insulation or the skeleton frame former. I don't know what the turn to
turn voltage holdoff voltage is since I cannot estimate the voltage in
60" streamers, but it must be pretty high. IMHO there is some other
factor at work in getting the energy to the top of the secondary, i.e.,
some kind of transmission line effect or some other as yet undefined