Re: Tracking inside secondary former

["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 Michael, 

A good example of carbon tracking occurred on a sparkgap I had built just to
see how it would perform (spinning copper pipes). During the testing, I had
found a great loss in performance and found that the wooden fixture used to
mount the stationary's to had carbon tracked. Obviously, this was due to
attaching the electrodes to the wooden frame rather than insulating them from
the wooden frame. Although the "gap" between stationary electrodes was huge,
the path provided by the wooden frame was conductive enough to conduct at the
high voltages. 

The same simple situation can occur on a secondary form, primary, etc... Where
there are voltage nodes large enough to conduct along a surface body (from one
node to the other), it will surely do so. Causes of this might be the form
material itself or even from the form being dirty. Once there is an arc from
point a to b, there will be carbon. This creates a conductive path until the
carbon track acts as a short (that's when the burning starts). 

I see basic principles involved here: voltage potential between two points and
if anything between the two points has a low enough resistance to arc at that
potential (air included). 

Bart 

Tesla list wrote: 
>
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <Clearspring1-at-aol-dot-com> 
>
> Hi David, 
>
> A clear success for your method!  I had been under the impression that the 
> disks had to be sealed to the secondary former, but obviously your method 
> works well in your setup. 
>
> I would still be most interested in hearing the theoretical underpinings of 
> how internal flashover and carbon tracking originate in the first place -- 
> the conditions and electrical dynamics that cause this phenomenon.  My 
> electrical background is pretty modest and some enlightenment on this would 
> help me and perhaps others.  Anyone? 
>
> Thanks! 
>
> Michael Tandy 
>
> > I have three spacers installed in my 12" Sonotube secondary tube. They are 
> >  cut out of a poly cutting board. They also have a 2" dia. hole thru the 
> > center 
> >  to pass the 1 3/4" electrical PVC conduit which also supports the toroid
> at 
> >  the top. I simply cut each spacer disc to where it was slightly smaller 
> than 
> >  the inside dia. of the Sonotube. They fit fairly snug, but can be slid up 
> > and 
> >  down inside the tube. Finally, I siliconed the disc spacers to the PVC
> con- 
> >  duit. This makes it easy to remove the toroid with the PVC conduit and the
>
> >  spacer disc in one piece for maint. or transport. As a result, the 
> secondary 
> >  coil is only 38" long, but I consistantly obtain 8 to 10 ft. sparks  with 
> >  occa- 
> >  sional hits near 11 ft point-to-point, and I haven't had any internal 
> >  flashover 
> >  or carbon tracking problems to date (been operational for over a year
> now). 
> > 
> >  David Rieben 
> >