Hi Ted, Grace The only requirement on distance between the EFT generator and the coupling clamp is a recommended maximum of 1m in Fig 6 (no minimum specified).
As regards distance between the clamp and the EUT, the standard states in section 7.2.1 that 'when using the capacitive clamp, the minimum distance between the coupling plates and all other conductive surfaces, except the ground reference plane beneath the coupling clamp shall be 0.5m' so I believe the answer to Graces second question is yes. In relation to the 0.5m cable length specified, there appears to be a contradiction in the standard as in Fig 8 for rack mounted equipment it indicates a 1m cable length. Does anyone know the reason for this? Mike Hurley Mead testing ltd www.meadtest.com From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 30 October 2007 12:16 To: [email protected] Subject: Re: EFT Setup Hello Grace, I do not believe that there is a specific separation requirement between the EFT generator and the coupling clamp. I have a system from Keytek that came with a 0.5 m cable to connect the generator and the clamp. If anything, I find supplied cable to be too short for my needs. From what I know, the capacitive clamp should not cause interference with the EFT generator even if they are in close proximity. The coupling clamp should not create significant radiated noise. In this I mean that the noise radiated by the clamp will be far less than that coupled into the EUT through the cable under test. There should not be a significant problem with the test if the EUT is less than 0.5 m from the clamp as long as you have the 0.5 m length of exposed cable that is specified. I will admit that I am not an expert in EMC measurements. I have been working with susceptibility testing for about eight years, but it only a fraction of the work that I perform. I am posting my opinion (and it is only an opinion) because I have not yet seen a response to your inquiry. I would like to encourage the more experienced EMC professionals to let me know if my though process is sound on this issue. If I am wrong, let me know; I am eager to learn more about the rationale behind the test procedure. Ted Eckert American Power Conversion/MGE http://www.apc.com/ The items contained in this e-mail reflect the personal opinions of the writer and are only provided for the assistance of the reader. The writer is not speaking in an official capacity for APC-MGE or Schneider Electric. The speaker does not represent APC-MGE's or Schneider Electric's official position on any matter. "Grace Lin" <gracelinnj@gmail .com> To Sent by: [email protected] [email protected] cc Subject 10/29/2007 02:24 EFT Setup PM Dear Members, I have two questions and appreciate your inputs: 1. Is there any clearance distance/requirement between an EFT generator and a capacitive coupling clamp (ccc)? 2. Is there any clearance distance/requirement between EUT and a capacitive coupling clamp (CCC)? From Figure 1 of IEC 61000-4-4, the cable length between the capacitive coupling clamp and the EUT "should be 0.5m +/- 0.05 m". Does this mean the distance between EUT and CCC should also be 0.5m? We built a 4ft x 8ft table with the same size of metal sheet (reference to ground reference) on top of it. I would like to place an EFT generator, CCC, and EUT on top of the table. Thank you for your time and look forward to your help. Best regards, Grace Lin - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.12/1098 - Release Date: 29/10/07 09:28 No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.15.16/1102 - Release Date: 31/10/07 16:38 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
