But it does if I apply 10,000 pulses (EFT normally on the power line) and after that the Hi-Pot test fails! That is what I am speaking of.
Doug Smith Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected] Website: http://dsmith.org ________________________________ From: Ralph McDiarmid <[email protected]> Sent: Wednesday, February 26, 2025 10:13:09 PM To: [email protected] <[email protected]> Subject: Re: [PSES] major safety issue possibly affecting 20% of the electronic devices in use 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 NkdkJdXPPEBannerStart Be Careful With This Message >From (Ralph McDiarmid ><[email protected]>)<https://godaddy.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f3eea39c9dcdb3e55709c86928fd287aa750d20c3d1b68f58aec9921440876d1afc1301618b606c6e469008ed70ac1eff69023cd22e7d736d68a4e4f8d6aeb598a7aa83a28168f278342343d621b0b5fbd8f131d264b499b29d0a5b6832840d6de5be908efb5d8711678aadcfaa150a49aa1b6ff416d61aea997541f9407bf30529a98793365435f03ab3af05b30cc798789d5fd4cdc55c916f851d5e028392fd09faea3b5ee4f8416062d29c84fbceac9b2a4f0d0fcce410511e2da2d84a433cb00585c8892ed27808c4138b81b3631b31eb396c9a5c404d> Learn More<https://godaddy.cloud-protect.net/email-details/?k=k1&payload=53616c7465645f5f3eea39c9dcdb3e55709c86928fd287aa750d20c3d1b68f58aec9921440876d1afc1301618b606c6e469008ed70ac1eff69023cd22e7d736d68a4e4f8d6aeb598a7aa83a28168f278342343d621b0b5fbd8f131d264b499b29d0a5b6832840d6de5be908efb5d8711678aadcfaa150a49aa1b6ff416d61aea997541f9407bf30529a98793365435f03ab3af05b30cc798789d5fd4cdc55c916f851d5e028392fd09faea3b5ee4f8416062d29c84fbceac9b2a4f0d0fcce410511e2da2d84a433cb00585c8892ed27808c4138b81b3631b31eb396c9a5c404d> 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 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 <[email protected]> Sent: February 26, 2025 4:17 PM To: [email protected] 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. 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