Re: air bubbles (fwd)
---------- Forwarded message ----------
Date: Tue, 19 May 1998 07:36:45 -0500
From: RODERICK MAXWELL <tank-at-magnolia-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: air bubbles (fwd)
Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Wed, 20 May 1998 00:12:02 +0300
> From: Harri Suomalainen <haba-at-cc.hut.fi>
> To: tesla-at-pupman-dot-com
> Subject: Re: air bubbles (fwd)
> >I am in the process of building one of two large capcitors that I
> >will use in series on the new coil I'm building. The problem is two of
> >the six sheets of poly I ordered have small air bubbles in them. Does
> >anyone know If this will cause the cap to breakdown? I'm using two
> It will cause problems. Depending on size and shape of bubble the
> electrical field in the bubble is many times the field on insulator.
> The answer is that instead of normal 20kV/mm (PE) you might
> need to derate it to perhaps 2-4kV/mm or it will fail pretty soon.
> Note that air is better insulator than this :)
As I have said in a reply to an earlier response I'll just use the
poly in some smaller caps so if they blow I won't lose to much! In the
mean time I ordered fresh poly to replace the defective sheets. I also
told the sales person I wanted it without holes or defects this time.
Thank you for your response, and help.