A note about MIL-STD-461. Obsolete versions (basic release through -461C) controlled conducted emissions to 50 MHz. But they did this by limiting the power cord length to a maximum of one meter from test sample to 10 uF feedthrough capacitor, the latter used instead of an inductive LISN. At 50 MHz, the power cord would be one-sixth wavelength, and there were instructions in MIL-STD-462 to physically scan the current probe looking for a current maximum. For radiated tests, the power cord length was increased to two meters. Unfortunately a lot of lazy people used one length or the other for all tests, to the point that when MIL-STD-461D/-462D came along, they scrapped the two different power cord lengths for a single length of 2.5 meters. The upper frequency limit was lowered to 10 MHz because of the longer leads. There is wording in the appendix to the effect that if control is desired to higher frequencies, the power cord length needs to be shortened.
RTCA/DO-160 controls conducted emissions over exactly the same frequency range as CISPR, namely 150 kHz to 30 MHz, although they used to mandate a 5 uH LISN and nowadays it seems like you could use any LISN impedance from 5 to 50 uH. Is that a correct interpretation? It doesn't seem right, but that's how I interpreted the latest curves. From: "Kurt Fischer" <kurt.fisc...@hyperinterop.com> Reply-To: <kurt.fisc...@hyperinterop.com> List-Post: emc-pstc@listserv.ieee.org Date: Thu, 29 Sep 2005 16:03:49 -0700 To: <emc-p...@ieee.org> Subject: RE: Measuring Conducted Emissions above 30 Mhz Hi all, A few standards come to mind depending on product application: MIL - STD 461/462 has conducted power line emissions measurements to higher frequencies (do not remember how high?). Also RTCA DO-160 for aircraft products / environments. Also consider CISPR 14 (absorption clamp method) for Household Products (or motors). This test method covers at least 300 MHz. Good Luck. Kurt Fischer From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Ken Javor Sent: Thursday, September 29, 2005 10:21 AM To: emc-p...@ieee.org Subject: Re: Measuring Conducted Emissions above 30 Mhz If you are going to make repeatable measurements two things have to hold true. The LISN has to continue to provide its function, and the LISN has to be close enough to the EUT that the mismatch between EUT, power cord and LISN doesn't cause vswr errors. At 30 MHz, the power cord should be l/10, or one meter. Of course that isn't the case, so there is already some question as to the accuracy of the present measurement stopping at 30 MHz. It is pretty easy to design a 50 uH LISN to 100 MHz, but you should check. Also, there are 5 uH LISNs that have been designed to 400 MHz. Above about 2 MHz, it doesn't matter whether you use a 5 or 50 uH LISN, so you have that possible alternative. If it were me, and I wanted to make accurate and repeatable CE measurements, I would either shorten the power cord to one-tenth wavelength, or I would go to a current probe measurement and slide the current probe up and down the power cord looking for peaks (spectrum analyzer in max hold while scanning frequencies and scanning the probe). I also think it would be very important to discriminate between different conduction modes, dm or cm or super-cm (current flowing same sense in phase, neutral and safety ground). From: "Garnier, David S (GE Healthcare)" <david.garn...@med.ge.com> List-Post: emc-pstc@listserv.ieee.org Date: Thu, 29 Sep 2005 10:55:58 -0500 To: <emc-p...@ieee.org> Subject: Measuring Conducted Emissions above 30 Mhz Hello EMC Guru's, I am looking for some guidance... Is there an established Standard & Test Method for measuring AC Power Conducted Emissions above 30 MHz (say to 150 MHz?) ((Obviously, CE limits for CISPR11 only go to 30 Mhz.)) Thanks for your time, Dave Garnier David Garnier e GE Health Care ___________________________________________ David S. Garnier Senior Technician Functional & CT Engineering 3000 N. Grandview Ave - M/S W-1250 Waukesha, Wi. 53188 Tel: 262.312.7246 Cel: 414.899.7580 - 2005 IEEE Symposium on Product Safety Engineering 3-4 October Schaumburg, IL http://www.ieee-pses.org/symposium ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - 2005 IEEE Symposium on Product Safety Engineering 3-4 October Schaumburg, IL http://www.ieee-pses.org/symposium ---------------------------------------------------------------- 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - 2005 IEEE Symposium on Product Safety Engineering 3-4 October Schaumburg, IL http://www.ieee-pses.org/symposium ---------------------------------------------------------------- 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 emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
