Hi All, A few years ago, I accidentally discovered during my research, that I can breakdown the AC mains barrier on many electronic devices with an 800 volt common mode pulse which appears to be due to the EMI line filter. After the pulse, the barrier was broken down several times in the next microsecond or so following my applied pulse. This happens in about 1/3 of the devices I have tested from small wall wart supplies to a 1.5 kW supply in a semiconductor fab. I published a portion of my results at an Institute of Physics symposium in England. My talk was as an associate of Oxford University and the paper went through the Oxford approval process. This information is taught in detail as part of my technical seminars now as well. The phenomenon was not described in the literature before my paper to my knowledge.
What I did not realize then was that breaking over the isolation barrier of a device on a regular basis, say a hundred times a day, could over time, damage the barrier, cause a Hi-Pot test failure, and the equipment would become a safety hazard unknown to the users of the device. So myself and an attendee at my class last week are setting out to see if this phenomenon is a hazard. If it is, then a large number of electronic devices in use, millions of them, are in fact safety hazards which would not pass a Hi-Pot test administered after a year in the field. My question is: have any of you looked into anything like this and would you like to join me? I have plans for measuring the breakdown of a barrier without significantly damaging it when testing it to breakdown. I have a coupe of ways of doing this. Then I need an appropriate pulse generator (with no moving parts). The only one that works to produce a pulse per second for days is made by Fischer Custom Communications in Torrance. CA. I have one so that is not a problem. If barrier damage is found, a significant rethinking of the Hi-Pot test is required and power supplies need to address this in their designs. I have some simple design changes that would accomplish this. Doug [https://lh4.googleusercontent.com/_HuR3Ky2TF_XhFHyxnYRmiq7nHQldnMsPNYFaLG6kb5T4y8MeCe-BDC_BscJtSFgszSSjssihHS-pjM3-jwNP8S0CwE-gN8fsRsPkojiAlmpBwb20vIVizS-siCUywW_jqrefbVr] - ---------------------------------------------------------------- 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
