🚀 go-pugleaf

In article <1992Oct9.153551.12624@infonode.ingr.com>, brantley@infonode.ingr.com (Dwight D. Brantley) writes...
>I am experiencing a breakdown of the insulating properties of a high
>voltage wire which seems to be related to several possible causes.  ...
>The anode wire insulation is breaking down either under the grommet or
>right at the edge of it resulting in high voltage arcing to the metal
>box.  The arcing leaves a hole in the insulation and can occur either
>inside the box or outside but is always associated with the grommet.

	Many hears ago, we did some study on some breakdown problems similar
	to yours. What we generally found was that if unexplained breakdowns
	were occurring it was because:

	For a wire in free space, with air at ground and reasonably humid
	air, (not the sahara,) you got a constant voltage gradient across
	the insulator.

	When you did anything (in our case, it was bending back the outer
	braid of a coaxial cable on itself, and attaching a ground wire,)
	you ended up with a 2 or 3 capacitor circuit, consisting of the
	various items there. In your case, the grommet is forming part of
	the 2-capacitor divider, (one cap is the material of the grommet,
	the other the material of the insulator of the wire.) What often
	happens is that high voltage goes across the grommet, causing
	corona, which causes ozone, which breaks down the chemical properties
	of the insulator, which breaks down, which shorts out.

	Main suggestion. Best insulator is air, other than that, you should
	have a hight voltage grommet. They look more like donuts with a thin
	membrane in the hole, and are maybe 1/2 or 1 inch in diameter, to
	reduce high voltage gradient.

   Frank R. Borger - Physicist    __       Internet:  Frank@rover.uchicago.edu
Michael Reese - Univ. of Chicago |___      Phone : 312-791-8075 fax : 567-7455
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