I think it's worth bearing in mind that hipot tests, both routine and prototype, done to verify clearance are to use either the 1,2/50us voltage impulse or an a.c. steady-state voltage burden. Solid insulation is verified by application of a.c. steady-state and by the 1.2/50us impulse voltage test. This is covered well in IEC 60664-1 and the 1.2/50us "surge" impulse waveform is well defined in ANSI C62.45
To use a different impulse waveform may result in failure or solid insulation but that doesn't necessarily mean the equipment under test is in some way faulty or unsafe when used in the overvoltage category for which it was intended. Ralph From: Richard Nute <ri...@ieee.org> Sent: February 26, 2025 4:17 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] major safety issue possibly affecting 20% of the electronic devices in use Hi Doug: I am alarmed that you experienced breakdowns by an 800-volt pulse when the dielectric strength of the primary circuits is at least 1500 volts rms. I have a few questions: 1. What was the 800-volt waveform? You applied the pulse common mode, which I assume is to both line and neutral conductors connected together and to the ground wire. (This is the hi-pot test configuration.) Please confirm. 2. How did you detect breakdowns, especially in the next microseconds after applying the pulse? 3. Small wall-warts are typically two-wire with no ground. (The hi-pot test is to foil wrapped around the enclosure and to the secondary.) What was your test configuration? 4. Primary-to-ground and primary-to-secondary in a typical product consists of Y capacitors, solid insulation, and air insulation. Since the air insulation is 2 mm or more, this is unlikely the site of the breakdown. Solid insulation should easily withstand 800 volts (more likely 8,000 volts). So, this leaves the Y capacitors as likely suspects. What is your guess as to the EUT component that exhibits this phenomenon? 5. Were any of the units you tested malfunctional or permanently damaged due to your tests? 6. How can we get a copy of your paper? Thanks, 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 EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ <https://www.mail-archive.com/emc-pstc@listserv.ieee.org/%20> Website: https://ewh.ieee.org/soc/pses/ <https://ewh.ieee.org/soc/pses/> Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html> List rules: https://pses.ieee.org/wp-content/uploads/2024/12/EM-PSTC-List-Rules.pdf For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net <mailto:msherma...@comcast.net> Rick Linford at: linf...@ieee.org <mailto:linf...@ieee.org> For policy questions, send mail to: Jim Bacher at: j.bac...@ieee.org <mailto:j.bac...@ieee.org> _____ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &A=1 - ---------------------------------------------------------------- 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-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://pses.ieee.org/wp-content/uploads/2024/12/EM-PSTC-List-Rules.pdf For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
