Re: Primary / Secondary Diameters

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Ralph, 

Tesla list wrote: 
>
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <Parpp807-at-aol-dot-com> 
>
> Hi List, 
> I posted a few days back a question about primary / secondary diameters for a
>
> bipolar 
> coil. I am getting ready to form the primary coil for my 48 inch, 4.5 inch 
> diam bipolar 
> secondary. Is there a way to determine what the diameter of the primary helix
>
> should be. My experience with a 20 inch bipolar is that the primary can get 
> no closer than 1.5 inches 
> from the secondary without arcover. But is this all trial and error, is there
>
> no way to 
> determine this? 
>
> Happy day, 
> Ralph Zekelman

In the past, trial and error and experience. But we now have Paul's excellent
program ACMI. I agree with Carlos that this would be a good place to check
coupling of your coil. You can use it to check various widths or positions and
what the mutual inductance and coupling will be for each. This should give you
a good idea of what the coupling will be at whatever diameter you use and can
therefore be a super tool. However, arc-over distance is horse of a different
color. 

Arcing between primary and secondary is primarily determined by the primary
wire radius of curvature, the distance between primary and secondary, and the
potential. The secondary should be seen as a large ROC at the size of the
secondary form due to the close proximity of the windings. I beleive there is a
paper at Terry's website identifying arc potentials in air using different
voltages and sphere's that could serve as a guide (or trial and error will do
the trick to). I'm not exactly sure where the paper is located at the site. 

Take care, 
Bart