[TCML] Primary Support Materials - surface tracking

[Peter Terren]

My observations about surface tracking:
Firstly, A spark will travel 3 times as far along a surface than through the 
air. Clearly shown here with an ignition coil with a 3 inch air gap and 9 
inch surface track.
http://tesladownunder.com/Ignitioncoilsinglesurfacetracking.jpg
So a piece of insulator placed where the field is greater than 10kV per inch 
(vs 30kV in air) will cause a short circuit. If that is a plastic then 
sustained sparking will burn.
Secondly, you can prevent the creeping carbon tracking by making sure that 
there is little e-field at the point of contact with an insulator so that no 
corona will form there.  If there is a conductor (eg a corona ring in air 
around the point of contact of conductor with insulator) then there is no 
corona in direct contact with the insulator and no nidus to start the burn.
I was getting carbon tracking down a 10 foot fibreglass fishing rod that I 
used to guide sparks in my Xmas 2007 project. I fixed the problem when I 
realised this and changed the end conductor to be at right angles rather 
than parallel with the rod.
http://tesladownunder.com/TeslaXmasRod.jpg
http://tesladownunder.com/Xmas.htm

Peter
www.tesladownunder.com

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From: "Bert Hickman" <bert.hickman at aquila.net>
Sent: Wednesday, August 25, 2010 3:48 AM
> Hi Gary,
> Unfortunately, PVC tends to track more quickly than many other polymers in 
> the presence of a corona discharge. ...
>
> Bert