HI folks,
I guess I finally had to weigh in on this one. We need to keep a few things in mind here: 1) The use of the EM Clamp is for when a CDN cannot be used, that doesn't mean when you don't own one. It means when it's impractical. 2) The clamp construction, described in one of the CISPR 16 documents, includes a capacitive line section. If you look in the clamp this is at the bottom. What this specifically means is that the clamp cannot be thought of as just another current injection probe. 3) The Clamp should be constructed so that the cable under test is pushed down against the capacitive line section: this is different to the CISPR 14 clamp where centering is desired. The assessor should have not asked for that, but, you should have known enough to argue back. 4) As for the height, I have to disagree. The EM Clamp has to be used over a ground plane, indeed, there is a mechanism for it to connect to the ground plane. I believe ( and stand ready to corrected ) that this is all part of forcing the clamp impedance, of which the capacitive strip plays a role. It would seem to me that the distance between this "plate" and the GRP is important. Maybe not so much at 150 kHz, but by the time we get past 200 MHz as required by some standards it will certainly be an influence. I don't believe an accredited lab or unaccredited lab should do this any differently, or with different equipment. The test is the test: period. Accreditation simply means 3rd party observation of what they do. In defense of assessors that do a fine job, if the standard calls for something, they will expect it. If the committee thought it important enough to define ( if there is leeway one would hope there are explanatory notes like in MIL STD 461 or DO-160 ), then it's appropriate to enforce. Shall Vs should, may, could etc. My 10 cents worth. Derek Walton L F Research. -----Original Message----- From: Wendy Nya <wendy...@yahoo.com> To: Cortland Richmond <k...@earthlink.net>; EMC- PSTC <emc-pstc@LISTSERV.IEEE.ORG> Sent: Wed, Nov 21, 2012 1:25 am Subject: Re: Fischer CC EM Clamp F-203I-32mm I think we have to give due respect to IEC and the many Experts who co-authored the standards. By giving more detail to the test setup and the equipment to be used, reduce the uncertainty and improve repeatability. I do agree that 30-50mm vs 75mm height has no significant impact. However, as an accredited lab, we do have to follow the standards rigorously. There are some assessors who will ensure that the standard is followed exactly, or be prepared to submit a 'method deviation' document. We bought a TESEQ clamp - it complies to the height requirement. The maximum diameter of the cable feeding is 20mm. From: Cortland Richmond <k...@earthlink.net> To: EMC- PSTC <emc-pstc@LISTSERV.IEEE.ORG> Sent: Wednesday, 21 November 2012, 7:26 Subject: RE: Fischer CC EM Clamp F-203I-32mm I've noticed that when people don't understand a test, they often try to make it conform to every detail in the standards, prescripitve or or not. If it really mattered, I suppose one could turn the clamp sideways... Cortland Richmond -----Original Message----- From: "Kunde, Brian" Sent: Nov 20, 2012 12:15 PM To: EMC- PSTC Subject: RE: Fischer CC EM Clamp F-203I-32mm Wendy, Who makes an EM Clamp that has a cable entry of 30mm? The size of the cores needed to handle a cable diameter of any size will be large enough to make this difficult if not impossible. Plus you have to have room for the input ‘N’ connector mounted under the cores. I have never seen an EM Clamp where the cable entry wasn’t 50mm or greater though I’m not saying one doesn’t exist. Typically they are more like 75mm. I don’t know where your supplier got this requirement. I don’t have the latest version of the 4-6 standard but the copy I have only states in section 7.2, “The cable between the AE and the injection clamp shall be kept between 30mm and 50mm above the ground reference plane”. The text doesn’t say anything about the height of the clamps or the cable height between the clamp and EUT, though the picture in figure 6 shows it as 30mm. I don’t see where the short distance the cable has to run higher than 30-50mm coming in and out of the clamp would have much impact on the test results. The Other Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Wendy Nya Sent: Tuesday, November 20, 2012 7:50 AM To: EMC- PSTC Subject: Fischer CC EM Clamp F-203I-32mm Dear All, We have a very old Fischer CC F-203I-32mm EM Clamp. A supplier pointed out that it does not comply to the 61000-4-6 standard's requirement - the height of the cable entry is more than the standard's requirement of 30-50mm. I just checked Fischer CC website. They are still selling this model. Is anyone still using it? Regards, Wendy - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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