Re: thin wire

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/30/01 2:00:37 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> Original poster: "Jason Johnson by way of Terry Fritz 
<twftesla-at-uswest-dot-net>" <
> hvjjohnson13-at-hotmail-dot-com>
>  
>  How high of a bang size or overall power could 26 guage wire take on a
>  secondary? I can get a whole bunch of really nice 26 guage silver plated 
> copper
>  wire w/ kynar insulation for a secondary coil but I want it to go on my 
next
>  system which could run up to ~15 KVA, but I don't know if it will handle a 
> 20
>  joule bang size or 10000 watts and above. I know that thin wire works very 
> well
>  on small systems and I have run 28 guage wire on a secondary up to 2kva 
> without
>  any problems but that was only a 2 joule bangsize and several hundred bps. 
I
>  don't want to blow this thing apart on its first run! What do you all 
think?
>   
>  Jason Johnson

Jason,

My guess is that no one has ever tried that but Richard Hull used 
30 gauge (I think) Kynar wire
for his magnifier resonator, at 6kW, and the wire ran quite warm.  
So I suppose your wire would run warm or hot especially at the
bottom of the secondary.  It may be somewhat inefficient too.  
You could wind the bottom part of the secondary with a thicker wire, 
and use the thin wire for the upper part.  But I'd be leery of wire
that thin at that power level in general.

Richard used 18awg magnet wire on his Nemesis TC
which he ran at 11kW, and the wire ran cool, at a medium
break rate.  So I think you could use something thinner such as 
22awg maybe, and it would work OK.  I'm not sure if I'd want to use 
thinner than 22awg.  I'm not sure how the 26awg would perform.  

I like to use about 1400 to 1600 turns on my secondaries, so
I would use a wire thickness that gives that many turns.  I've
never built any high powered coils, but I don't see any reason why
they should behave differently than small ones, regarding the
number of turns.  After all, it's all proportional.  Space winding
with a somewhat thinner magnet wire may actually give lower 
losses, due to a reduced proximity effect.  Kynar insulation 
may give a good spacing for minimal proximity effects?

A secondary coil for 15 or 20kVA will need to be rather large
anyway, especially if you use a low break-rate.  The coil may
need to be 70" tall (?) for a low break-rate, in which case close-
wound 18awg magnet wire might be a good choice.

Perhaps someone will make comparisons of thick vs. thin
wire on large coils someday.

John Freau