Re: calculating safe primary turn-to-turn distance

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

On 25 Aug 00, at 23:43, Tesla list wrote:

> Original poster: "Stan" <sdarling-at-columbus.rr-dot-com> 
> 
> Greetings all,
> 
> I have been curious since I started doing Tesla coils about this:  how
> does one calculate the minimum air distance of turn to turn spacing in a
> primary for a given voltage?  I'm not an EE so my common sense tells me
> that current always favors the path of least resistance and that even a
> tiny distance of air would have a much greater R than the adjacent half
> turn of Cu tubing. So if the adjacent turns weren't touching, why would
> it ever arc over through the air?  I suspect it has something to do with
> the inductance of the Cu tubing coil(s) ....

You're right - and certainly not stupid. An easy approach is 
to divide the peak primary voltage you will ever run the coil 
with by the number of turns to get a volt/turn gradient. You 
can base spacing on that but there is a catch - turn-turn 
flashover will most likely occur at the insulating supports as 
tracking over the insulators is a favoured path for a spark to 
follow. So spacing should really take this into account rather 
than the airgap between the turns.

Regards,
Malcolm
 
> Feeling stupid in Ohio.
> 
> -Stan
> 
> 
>