There is a breakdown of a barrier for multiple times (I can see the conducted emission of the multiple breakdowns from each EFT pulse) there is no permanent damage. My worry is that since it can be triggered by EFT which is a burst if many pulses, and happens frequently on the ac mains (I have seen many in minutes) we quickly accumulate thousands of breakdowns and I worry about accumulating damage. I have seen this effect of accumulating damage in other settings before. In one case it took 10,000 hits to eventually cause permanent damage. I presented a DesignCon paper a few years ago on that case which was different than the current case.
In each of the many supplies I have tested I don’t know if the breakdown was an air gap not adjacent to an insulator or if the breakdown was along or through an insulator. I need it sacrifice some supplies to see but I expect both types. Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: d...@dsmith.org Website: http://dsmith.org ________________________________ From: Ralph McDiarmid <rmm.priv...@gmail.com> Sent: Friday, February 28, 2025 3:27:12 PM To: EMC-PSTC@LISTSERV.IEEE.ORG <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] major safety issue possibly affecting 20% of the electronic devices in use It’s always better to have a defined term. In this context IEC 60664-1 defines electrical breakdown as “failure of insulation under electric stress when the discharge completely bridges the insulation, thus reducing the voltage NkdkJdXPPEBannerStart Be Careful With This Message >From (Ralph McDiarmid ><rmm.priv...@gmail.com>)<https://godaddy.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f93819458848d9a29a43f49a778a0d338277d4c1db839919d89e15858c8c7ed35c6b8f0e12604b4642168ee357bd4edee384d2c3934cbba08342fdb9ffb81add53a5e72f0bac380b22c12798c162f837ecf51dda92428bdfcdc8557e64607fdc47b98f7cb028432e2259d4dd6ec3084f075e70d6d7aa79ca9b89988c781a424f2e3604544561ffe623097ba4228c7c752c4647f65cc1df99ce76952fb4d1957050203fb6f074fc3c0c2018d2abe2a0960510081e1c645b95bda01283c24a02c203218553498e15207274fbf789ce5ce9cb0b0afbfa14d1d58> Learn More<https://godaddy.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f93819458848d9a29a43f49a778a0d338277d4c1db839919d89e15858c8c7ed35c6b8f0e12604b4642168ee357bd4edee384d2c3934cbba08342fdb9ffb81add53a5e72f0bac380b22c12798c162f837ecf51dda92428bdfcdc8557e64607fdc47b98f7cb028432e2259d4dd6ec3084f075e70d6d7aa79ca9b89988c781a424f2e3604544561ffe623097ba4228c7c752c4647f65cc1df99ce76952fb4d1957050203fb6f074fc3c0c2018d2abe2a0960510081e1c645b95bda01283c24a02c203218553498e15207274fbf789ce5ce9cb0b0afbfa14d1d58> Potential Impersonation The sender's identity could not be verified and someone may be impersonating the sender. Take caution when interacting with this message. NkdkJdXPPEBannerEnd 1. It’s always better to have a defined term. In this context IEC 60664-1 defines electrical breakdown as “failure of insulation under electric stress when the discharge completely bridges the insulation, thus reducing the voltage between the electrodes almost to zero” 2. Doug, as far as I can tell from your previous message, you have not clearly defined the effect to which you have referred a few times. Is the effect a permanent failure of solid insulation causing a subsequent hipot test to fail? At my last employer before retirement, we always asked the question, “what is the problem we’re trying solve ?” If there wasn’t an obvious or definable problem, we moved on to more pressing matters so to avoid fixing what is not broken. Ralph From: Richard Nute <ri...@ieee.org> Sent: February 28, 2025 1:54 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 think that we hold different definitions for “breakdown.” In safety, “breakdown” signifies 1. failure of solid insulation (in ohms) to withstand the test voltage (for one minute), or 2. an arc through air insulation at a voltage less than the test voltage. In both cases, a hi-pot tester would trip, regardless of current setting. The failure of solid insulation can be verified by an ohmmeter (which, if good, would be near the upper limit of the ohmmeter). Your measurements do not appear to comprise a safety-related breakdown. The question I have is: What is the ohmmeter measurement before and after the pulse test? Well… we don’t know the “before” measurement. But, an “after” measurement should indicate whether or not damage to solid insulation has occurred (resistance is less than 5 megohms - say). Or, a leakage current test. Another question: Why did you choose to do the pulse test with the equipment under test not powered on? Best regards, Rich From: doug emcesd.com <d...@emcesd.com<mailto:d...@emcesd.com>> Sent: Thursday, February 27, 2025 6:30 PM To: ri...@ieee.org<mailto:ri...@ieee.org>; EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] major safety issue possibly affecting 20% of the electronic devices in use Thanks for the information. But in this case breakdown is occurring and the question is if it can be problematic. 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