And we shouldn't confuse dielectric withstand rating with continuous working voltage rating. _______________________________________ _____________________________________________
Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: richardn...@comcast.net To: EMC-PSTC@LISTSERV.IEEE.ORG List-Post: emc-pstc@listserv.ieee.org Date: 06/22/2011 02:59 PM Subject: [PSES] Repeated Hi-Pot Testing - Destructive? ________________________________ Hi Richard: Insulation breakdown starts with partial discharge in very small voids. PD takes time to form. It usually won't get started in the typical 1-minute hi-pot test. After the voltage is removed, any ionized air in the void slowly dissipates, so the PD event starts from zero at the next test. At last year's PSES Symposium in Boston, there were two presentations on insulation breakdown mechanisms. Some years ago, I connected several power supplies in parallel to a hi-pot tester. I ran the tester for 8 hours/day, 5 days/week. After about 1-1/2 weeks, I detected some insulation abnormalities. At the relatively low voltages that we use for hi-pot testing, the very good typical insulations, and the low frequency of recurrence of the test, damage to insulation is not likely. Don't worry about it. Best regards, Richard Nute Product Safety Consultant Vancouver, Washington - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ http://product-compliance.oc.ieee.org/> Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> Instructions: http://listserv.ieee.org/request/user-guide.html <http://listserv.ieee.org/request/user-guide.html> List rules: http://www.ieee-pses.org/listrules.html <http://www.ieee-pses.org/listrules.html> For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. ______________________________________________________________________ - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
