Hi John and the group,
Thanks! The data I saw is in a paper that was submitted to the EMC
Symposium in Dresden and left me with the impression it was new. Having
read the paper, I set up an experiment in the lab and true enough, the
discharge current onto an insulator (amps for ns or so) is quite
different for - and + discharges, much greater for -. The application
was for the exposed parts of systems but looks like it could affect
nearby breakdown in air too.
I do a lot of this kind of thing. When I come across new (to me)
information, I set up an experiment to measure the effect. Sometimes I
find that there are a lot of caveats in published material that were
not mentioned. The first time I did this, I was around age 12 and I
recreated one of Marconi's experiments in my bedroom to make sure it
really worked.
Doug
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--------------------------------------------------------------
Doug Smith
P.O. Box 60941
Boulder City, NV 89006-0941
TEL/FAX: 702-570-6108/570-6013
Mobile: 408-858-4528
Email: [email protected]
Web: http://www.dsmith.org
--------------------------------------------------------------
On Wed, 5 Aug 2015 21:57:19 +0100, John Woodgate <[email protected]> wrote:
In message <[email protected]>, dated
Wed, 5 Aug 2015, Doug Smith <[email protected]> writes:
>Actually, discharges involving insulators appear to be polarity
>senstive from recently published data. I have confirmed this with
lab >measurements. Not sure how this effects safety.
I don't think this is particularly new, although no doubt it's much
better quantified these days. The chemical composition affects if,
and how much, ionization and consequent electron emission occurs at
the surface. So if the discharge path has different insulating
materials at each end, polarity sensitivity is to be expected.
-- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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