The point is that creepage distances are determined such as that within the limits of pollution degrees 1-3 , no substantial leakage current(eventually leading to breakdown of the insulation) develops. Yes the reaction starts immediately (salt/electrodes) but the deterioration takes time.
Testing with carbon would lead to infinite creepage distances. Apparently the relation between voltage and insulation deterioration was derived very experimentally .... read here: http://www.google.nl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=25&ved=0CE0Q FjAEOBQ&url=http%3A%2F%2Fwww.denverpels.org%2FDownloads%2FDenver_PELS_20 090915_Aldous_Insulation_Coordination.pdf&ei=9ftxU-nfKcSYyQP1-4CoDg&usg= AFQjCNF8HDOXxH04EA3m_dLXItAyT5CqKg&bvm=bv.66330100,d.bGQ&cad=rja Regards, Ing. Gert Gremmen, BSc -----Oorspronkelijk bericht----- Van: John Woodgate [mailto:[email protected]] Verzonden: Tuesday, May 13, 2014 12:54 PM Aan: [email protected] Onderwerp: Re: [PSES] Creepage and RMS In message <[email protected]>, dated Tue, 13 May 2014, "ce-test, qualified testing bv - Gert Gremmen" <[email protected]> writes: >That would always constitute a failure, as a creepage failure is not a >defined discharge as with clearance, but more a leakage current >phenomena. If you fill up the gap with a conductive substance there >*will* be a leakage current. I don't see the point you are making. The whole idea is that the pollution becomes a conductive substance even if it didn't start as other than a rather poor insulator (there must be some initial current, even if it's picoamps). -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus 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]>
