Well said, Derek! I am always amazed that EMC people worry about the measurement uncertainty of the coax cable that connects the target to the scope yet ignore factors, like lack of reasonable waveform definition, that have orders of magnitude more effect on the EUT.
Doug Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected] Website: http://dsmith.org ________________________________ From: DEREK WALTON <[email protected]> Sent: Tuesday, October 15, 2019 11:51:15 AM To: doug emcesd.com <[email protected]> Cc: EMC-PSTC <[email protected]> Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) Hi All, Well, this seems like here we go again. Not you Doug, just to be clear. I have long since had a problem with the standards world where they focus on a “test” rather than addressing the REAL PROBLEM. I’ll give $100 right now to the three people who can shuffle the carpet, discharge into an ESD Target and get the 61000-4-2 wave-shape. Seriously,, I’m waiting for the first lawsuit against someone that says a products good because it passes the “std test”. To attempt to drive a standard to anally specify a naturally occurring random event is ludicrous. At best what should be done is a range of parameters specified and the simulator lie within them. Why? Well who benefits when the standard is made more specific TO THE WRONG QUANTITY!!!??? Certainly not the consumer, who is the main reason we are doing this. To quote a good friend Harry Hodes, we are trying once more to increase the accuracy of measuring Jelly with a micronometer. If the standard needs improving, it would be a change to reflect more what happens in the real world not further restrict a clinical lab test. Back to my coffee, Derek. On Oct 15, 2019, at 12:33 PM, doug emcesd.com<http://emcesd.com> <[email protected]<mailto:[email protected]>> wrote: A few years ago I evaluated eight ESD simulators over a year’s time at Bob Vermillon’s lab at the NASA Ames campus, https://esdrmv.com<https://esdrmv.com/>. All had current cal stickers and two of the eight produced very non-compliant waveforms! This is a good argument that calibration one a year does not guarantee much and that validation need to be performed every day. There are several articles on ESD simulators on my website around the same time including this one: https://emcesd.com/tt2010/tt120210.htm 25% failure rate is not good and adds to the problem of repeatable testing. I have spent nearly 30 years now investigating ESD and ESD simulators! My first foray into high power/high voltage was 58 years ago with a pair of 811a vacuum tubes generating 600 watts of power at 300 kHz which I fed to a resonant air core transformer to make a high powered Tesla coil (at age 14). I figure I played in a field of more than 10,000 Volts/meter for hours on end, occasionally letting the 811a tubes cool down before they melted. Brought the FCC to my house, a story for another time. Pieces of metal in the vicinity got hot from induction heating as well as an incandescent bulb held by the base would light up, not to mention fluorescent tubes nearby, with or without wires attached. I have been fascinated by high voltage ever since. Doug Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected]<mailto:[email protected]> Website: http://dsmith.org<http://dsmith.org/> ________________________________ From: John Woodgate <[email protected]<mailto:[email protected]>> Sent: Tuesday, October 15, 2019 9:27:08 AM To: doug emcesd.com<http://emcesd.com/> <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) I take your point, but I wasn't proposing a full replication of the earlier work. A confirmatory paper or two, citing the earlier work and using modern measuring instruments, and indeed looking at the environment factor, would support the case for improving the standard. By 'environment factor' I refer to the recent report that different results with the same equipment were obtained in an absorptive environment and in a screened room. Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk<http://www.woodjohn.uk/> Rayleigh, Essex UK On 2019-10-15 17:18, doug emcesd.com<http://emcesd.com/> wrote: That is true, but only after the author was familiar with all previous work. The work was comprehensive and it is hard to imagine a different result happening. Anyone who wants to restudy the subject will need a BIG budget, just for all the round robin testing that was done. Bell Labs contributed more than one million $ to the effort by my calculation, not to mention many other companies. I bet the total effort was ten million $! Doug Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected]<mailto:[email protected]> Website: http://dsmith.org<http://dsmith.org/> ________________________________ From: John Woodgate <[email protected]><mailto:[email protected]> Sent: Tuesday, October 15, 2019 00:52 To: doug emcesd.com<http://emcesd.com/>; [email protected]<mailto:[email protected]> Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) No doubt it was very good work, but its OLD. One or two new papers would be a good thing. Best wishesJohn Woodgate OOO-Own Opinions OnlyJ M Woodgate and Associates www.woodjohn.uk<http://www.woodjohn.uk/>Rayleigh, Essex UK On 2019-10-15 06:39, doug emcesd.com<http://emcesd.com/> wrote: This was pretty much done in the 90s with many round robin tests. The culprit is the lack of di/dt control and lack of control on EM radiation from the simulator. The two factors dominate everything else. No need to duplicate previous work. Just read the papers on the results from the significant amount of research that was done, of which I was a part. Doug Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected]<mailto:[email protected]> Website: http://dsmith.org<http://dsmith.org/> ________________________________ From: Ken Javor<[email protected]><mailto:[email protected]> Sent: Monday, October 14, 2019 8:17:52 PM To: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) No insight into what Doug mentioned, but before tightening up on equipment performance requirements, with attendant cost impact to test facilities, I would want to know that the variability between test facilities due to practice are not the dominating factor. I would want to improve test procedure controls to where everyone does the test close enough to the same that if there is still unacceptable variability, then, and only then, do we look at the test equipment. In order to assess that, you would round-robin using the same model of gun. Perhaps that is one of the many things to which Doug referred. Ken Javor Phone: (256) 650-5261 ________________________________ From: "doug emcesd.com<http://emcesd.com/>" <[email protected]><mailto:[email protected]> Reply-To: "doug emcesd.com<http://emcesd.com/>" <[email protected]><mailto:[email protected]> Date: Mon, 14 Oct 2019 19:41:42 +0000 To: <[email protected]><mailto:[email protected]> Conversation: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) Hi Montara, There are more stories than I can type here. The standard as written is not very good. We addressed this in the early to mid-1990s and determined what was necessary. We also did a lot of round robin testing. Probably most of what you want has been published in the 1990s. Look at the ESD Association papers from the era. Look for authors like myself (we were all involved with revising 61000-4-2), Jon Barth, Ken Hall, Hugh Hyatt. Everything you need was done back then and rejected by the EU members for various reasons that I do not consider valid. Sent from my iPhone IPhone: 408-858-4528 Office: 702-570-6108 Email: [email protected]<mailto:[email protected]> Website: http://dsmith.org<http://dsmith.org/> ________________________________ From: Monrad Monsen<[email protected]><mailto:[email protected]> Sent: Monday, October 14, 2019 9:43:54 AM To: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> Subject: [PSES] Any Different Results in ESD Testing when Changing Brands of ESD Simulator (IEC 61000-4-2) Hi! Does anyone have any stories that can be shared of a product getting a different ESD test result when changing the brand/model of ESD simulator? I am a member of the US Technical Advisory Group (TAG) for CISPR/I international standards committee (Electromagnetic compatibility of information technology equipment, multimedia equipment and receivers). There is a proposal that SC77B begin work on changes to IEC 61000-4-2 (ESD) to improve the ESD waveform verification (some call this “calibration”) because under today’s rules different simulators create different levels of high frequency signal content which some believe is the primary reason for different test results. Some believe that the IEC 61000-4-2 waveform requirement fails to include any evaluation of the slope (dV/dt or dI/dt) of the impulse, and that uncontrolled parameter directly affects spectral content. I would like to know if anyone has experienced any actual ESD test result consistency when using different Brand/model ESD simulators even though they are all calibrated simulators under today’s rules. I admit that our company uses the same brand & model ESD simulator as local labs, so I have never observed this issue myself. My initial preference is to not add cost to testing and avoid forcing labs to buy new ESD simulators, but perhaps this cost is warranted if there are actual wide variations in ESD test results depending on the brand of ESD simulator. Thanks. Monrad Monsen | Hardware Compliance Strategist Phone: +1.303.272.9612 Oracle Market Access & Hardware Compliance Strategy 500 Eldorado Blvd | Broomfield, CO 80021 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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