Re: [PSES] test setup for table top ungrounded equipment 61000-4-2 IEC:2008 figure 6 page 20

[Douglas Smith]

I don't think 1 or 2 MOhms will make much difference for one second application of ESD pulses. Tc = RC = 10**6 x 100*10**-12 = 10**-4 seconds (100 pF estimated, not calculated between HCP and GRP. Even 10X that capacitance would still yield a Tc of 1 ms, or 2ms for 2MOhm). Doug ------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 60941 ========= Boulder City, NV 89006-0941 _ / \ / \ _ TEL/FAX: 702-570-6108/570-6013 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: d...@dsmith.org \ _ / ] \ _ / Website: http://www.dsmith.org ------------------------------------------------------- On 3/6/13 4:48 PM, McInturff, Gary 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:danp...@verizon.net] Sent: Wednesday, March 06, 2013 4:44 PM To: McInturff, Gary; EMC-PSTC@LISTSERV.IEEE.ORG 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:dan.ro...@ieee.org     From: McInturff, Gary [mailto:gary.mcintu...@esterline.com] Sent: Wednesday, March 06, 2013 6:20 PM To: EMC-PSTC@LISTSERV.IEEE.ORG 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. Wilbur Avenue Coeur d’Alene, ID  83815-9496 Toll Free: 800-444-5923 X1XXX Tel:  (208) 635-8 Fax: (208) 635-8   www.esterline.com/interfacetechnologies   Technology, Innovation, Performance…   Click here to read disclaimer     - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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