Common sense says that as in ESD tests on isolated EUTs a bleeder resistor set
can be applied to discharge before applying next impulse. Otherwise the test could be carried out in DC mode. Not sure of the "committee" responsible for the standards text was aware of ESD practices. Seen the 0.0005 microfarad capacitor specification I don't think so. Gert Gremmen From: Nyffenegger, Dave [mailto:[email protected]] Sent: Monday 29 June 2015 21:07 To: [email protected] Subject: Re: [PSES] Optos for PELV isolation HI Rich, The standard also says 5 second interval between discharges. And the test must be run on 20 samples. We know UL likes to test. First edition of the standard is 1984, the test has probably been in there since the beginning. -Dave From: Richard Nute [mailto:[email protected]] Sent: Monday, June 29, 2015 1:51 PM To: Nyffenegger, Dave; [email protected] Subject: RE: [PSES] Optos for PELV isolation Hi Dave: "subjected to 50 discharges from a 0.0005 microfarad capacitor that has been charged to a potential of 20 kV between the short-circuited input and short circuited output terminals." Okay, 500 pF charged to 20 kV then applied to the opto isolation. The input-to-output capacitance is on the order of 1 pF. That means nearly the full 20 kV is applied across the isolation barrier, and exponentially decays by the insulation resistance. One opto specs the insulation resistance at 100 Gohms minimum! Time constant is 500e-9 x 100e+9 or 50000 seconds or 833 minutes or 13 hours! Repeated 50 times! 50 days to do the test, at 5 days per week, 10 weeks, 2-1/2 months! I must be missing something. Test does not make much sense. Best regards, Rich - ---------------------------------------------------------------- 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) <http://www.ieee-pses.org/list.html> 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]>
