The capacitance between EUT and 40 cm plane (be it V or H) Is the return path for the common mode current on the mains lead.
Make the capacitance smaller (d> 40 cm) then emission decrease, Make it higher (d < 40 cm) then emissions increase. 40 cm is a good compromise for EUT with irregular surfaces and common sizes. Only for CM current ! There are proposals to allow for measurement of house-hold equipments such as vacuum cleaners on a 10 cm from ground. This definitely means more conducted emissions. Rationale: Vacuum cleaners normally operate close to a conductive ground. Note that the LISN measures both CM and DM current, with a coupling factor of -6 dB There is discussion about the coupling factors when ground lead Is connected, so be aware of that. Gert Gremmen Ce-test, qualified testing bv Van: [email protected] [mailto:[email protected]] Namens Ken Javor Verzonden: woensdag 23 september 2009 17:24 Aan: [email protected] Onderwerp: Re: [PSES] Conducted emission measurements Rephrase the question: From an electrical point-of-view, how does the presence of a vertical ground plane at 40 cm separation affect conducted emissions? Ken Javor Phone: (256) 650-5261 ________________________________ From: <[email protected]> List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Wed, 23 Sep 2009 10:16:11 -0500 To: Ken Javor <[email protected]> Cc: <[email protected]> Subject: Re: [PSES] Conducted emission measurements Ken and List, It was explained to me as: to simulate a file cabinet next to a desk in an office environment type of setup. This is just one example I recall from the various audits I've been through over the years. Michael Sundstrom Electronic Lab Analyst Overhead Door TREQ Center, Dallas [email protected] OFC: 214-579-6312 CELL: 940-390-3644 KB5UKT Ken Javor <[email protected]> 09/23/2009 09:56 AM Please respond to Ken Javor <[email protected]> To [email protected] cc Subject Re: [PSES] Conducted emission measurements What is the rationale behind a vertical conducting surface for conducted emissions? Ken Javor Phone: (256) 650-5261 ________________________________ From: Wan Juang Foo <[email protected]> List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Wed, 23 Sep 2009 13:46:27 +0800 To: <[email protected]>, <[email protected]> Cc: Wan Juang Foo <[email protected]> Subject: Re: Conducted emission measurements Hello Tim, I may be missing. Is there such a 40 cm height? Here is my 5 ยข worth. These are some of the the special provision for conducted emission testing: To meet EN 55011, I suppose since 1999?? the measurement may be carried out: - on the radiated emission test site (same EUT configuration) - above a metal ground plane which shall extend at least 50 cm beyond the boundary of the equipment under test and have a minimum size of 2m x 2m - within a screened room; either the floor or one wall of the screened room shall act as the vertical ground plane .. CISPR 22 since (1993) and Amendment 1 (1995) Table- top EUTis to be placed 40 cm from a vertical metal reference plane (e.g. a wall of a screened room/enclosure) "The EUT, where intended for table-top use, shall be placed 0,4 m from a vertical metal reference plane of at least 2 m by 2 m and shall be kept at least 0,8 m from any other metal surface or other ground-plane not being part of the EUT. If the measurement. is made in a screened enclosure, the distance of 0,4 m may be referred to one of the walls of the enclosure." Floor- standing EUT on a horizontal metal ground- plane, not in metallic contact with the ground- plane. Metal floor of a screened room may replace the reference ground- plane best regards, Tim Foo Expert Witness, EMC and Product Safety ECE, School of Engineering, http://www.np.edu.sg/ece/ <http://www.np.edu.sg/ece/> <http://www.np.edu.sg/ece/> DID: +65 6460 6143 Ngee Ann Polytechnic, 535 Clementi Road, Fax: +65 6467 1730 Singapore 599489 [email protected] wrote on 23/09/2009 06:06:05 AM: > Hello Group, > > I have a question about the conducted emission measurements > performed in a semi-anechoic chamber. > > CISPR 22 requires the use of a vertical ground plane when testing > tabletop EUTs, unless you mount your EUT on a non-conductive table > 40cm above the horizontal ground plane (instead of the traditional 80cm) > > I did not find a requirement for a vertical ground plane when > testing floorstanding equipment. If one opts to use the alternative > method of not using the vertical ground plane, can floorstanding > equipment also be tested without the vertical ground plane? The > horizontal ground plane is always present since that is the chamber floor. > > What are most labs using? We have the option of making a removable > vertical ground plane "wall" or mounting the equipment on a 40cm table. > > Thanks, > Tim Pierce > - ________________________________ NOTICE: This message may contain privileged/confidential information. If you are not the intended recipient of this email, please delete it immediately and notify the sender . - 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] <mailto:[email protected]> <mailto:[email protected]> > All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc <http://www.ieeecommunities.org/emc-pstc> <http://www.ieeecommunities.org/emc-pstc> Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> <http://www.ieee-pses.org/> Instructions: http://listserv.ieee.org/request/user-guide.html <http://listserv.ieee.org/request/user-guide.html> <http://listserv.ieee.org/request/user-guide.html> List rules: http://www.ieee-pses.org/listrules.html <http://www.ieee-pses.org/listrules.html> <http://www.ieee-pses.org/listrules.html> For help, send mail to the list administrators: Scott Douglas <[email protected] <mailto:[email protected]> <mailto:[email protected]> > Mike Cantwell <[email protected] <mailto:[email protected]> <mailto:[email protected]> > For policy questions, send mail to: Jim Bacher <[email protected] <mailto:[email protected]> <mailto:[email protected]> > David Heald <[email protected] <mailto:[email protected]> <mailto:[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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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]>
