Another aspect: Part of internal insulation may be behind a semiconductor (diode) so the full DC potential would develop over the diode and not the insulation. In most cases the diode does leak more than the insulator, but in those cases where the insulator is bridged by a resistive circuit, the test would be incomplete.
Gert Gremmen -----Original Message----- From: John Woodgate [mailto:[email protected]] Sent: Thursday 6 August 2015 06:42 To: [email protected] Subject: Re: [PSES] Dual polarity DC electric strength test In message <[email protected]>, dated Wed, 5 Aug 2015, Doug Smith <[email protected]> writes: >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 -. If he discharge was from a metal electrode, the discharge with the metal negative would be expected to be greater because there are lots of electrons floating around in the metal and once they get to the surface they are repelled by the field. It might be interesting to look at the discharge between PTFE (tightly-bound electrons) and, say, polythene (less tightly bound). Again, polythene negative would probably give a stronger discharge, -- 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 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
