How about the return path of the esd gun ? Part of the ESD effect is the H-field during discharge in the ground loop.
The highest frequencies discharge to the internal “air”capacitor (single plate capacitor) in the gun, but eventually a (still high frequency) current (10Amps or so) flows through the ESD gun’s ground cable to the ground plane of the setup. A different lay-out of the return cable produces a different loop and EUT H-field. I agree with Douglas that the discharge resistors (if not to parasitic) do not impact the impulses at all. (unless they are SMD ;<)) ). Gert Gremmen Van: [email protected] [mailto:[email protected]] Namens McInturff, Gary Verzonden: donderdag 7 maart 2013 17:00 Aan: 'Ken Wyatt' CC: '[email protected]' Onderwerp: RE: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20 Agree, but nothing I can do about that, so I’m making sure what I can control is in fact controlled. (It has been tested during earlier development at two different sites, and different ESD guns with similar result acceptable results, and in fact margin tested. But by the time it got to the customers lab I first noticed that they were not actually following the specification. I pointed that out and they made some corrections per the standard, but I still think there is a difference. Whether or not the difference is part of the problem or not is undetermined at this point, but as that part of the equation can be handled if we just had a definitive definition of setup up so that we can just not have to worry about that while finding and solving the root problem. Thanks Gary From: Ken Wyatt [mailto:[email protected]] Sent: Wednesday, March 06, 2013 5:36 PM To: McInturff, Gary Cc: [email protected] Subject: Re: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20 Are you both using the same ESD simulator? There's a huge difference between different brands, with some producing large radiated E-fields. Kenneth Wyatt Wyatt Technical Services LLC Woodland Park, CO [email protected] www.emc-seminars.com (Sent from my iPad) On Mar 6, 2013, at 5:48 PM, "McInturff, Gary" <[email protected]> wrote: The problem is I don’t know if it makes a difference Dan. We certainly were getting different results from a lab – and I trust the lab itself. But it didn’t match what I had here nor the results from my normal certification lab. We tested two units and got the same results, and now the customer uses yet another lab with different results. Even given the vagrancies of ESD testing I can’t put my finger on the problem. That’s what got me to verifying the setup. Incidentally during the original successful tests I actually tried it both ways, with the bleed cables in parallel, and with the HCP cable removed – as I suspect should be the case (maybe) and that didn’t make a difference at that time. But as I said I’m trying to eliminate the easy stuff first – test setup, both mine and the lab that is failing the equipment. Thanks Gary Gary From: Dan Roman [mailto:[email protected]] Sent: Wednesday, March 06, 2013 4:44 PM To: McInturff, Gary; [email protected] Subject: RE: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20 Interesting. I have done the testing with the bleeder cable as described connected in parallel, not in series with the HCP bleeder. Maybe I was doing it wrong though? But as you said, it does not make sense—but does it make a difference? Is it shown as set up that way merely as a closer more convenient connection to the EUT? Reading the text and ignoring figure 6 would lead me to believe it was in parallel. ______________________________________________________ Dan Roman, N.C.E. VP of Communications Services IEEE Product Safety Engineering Society mailto:[email protected] From: McInturff, Gary [mailto:[email protected]] Sent: Wednesday, March 06, 2013 6:20 PM To: [email protected] Subject: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20 Ladies and germs I was confirming this set-up and found something confusing. The picture shows the cable which is used to remove charge from the EUT between successive ESD discharges and having 2 470k Ohm resistors, the same basic setup as between HCP and ground plane or VCP and ground plane. Not surprising, but in looking at the picture it implies that this cable ends up being in series with the HCP/GP bleeder cable. That would make the series resistance during discharge to be rough 2 Mohm rather than 1 Mohm. That doesn’t seem right to me. The reference text doesn’t really what happens to the hcp discharge cable either. In fact the cable for the VCP would seem to be placed in parallel with the HCP bleeder cables during indirect contact discharges to the VCP. I don’t believe that is true either. I believe for the VCP setup the HCP cable is disconnected from the HCP and then hooked up to the VCP. I kind of expected the bleeder cable for the ungrounded equipment bleeder cable would do the same thing. The HCP cable removed and it could be used as the EUT bleeder resistor wire as well. In the first case the bleeder and the HCP bleeder cable appear to be in series, and in the second the bleeder and the HCP would be in parallel if it wasn’t disconnected from the HCP. I do have a pdf of the figure but not allowed to attach to this email. Thoughts. Gary McInturff Reliability/Compliance Engineer Esterline Interface Technologies Featuring ADVANCED INPUT, GAMESMAN, LRE MEDICAL, and MEMTRON products 600 W. 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To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
