Hi Chris, In general, due to length of wires (signal wires) and associated wavelengths of the frequencies assessed at conducted emi measurements ( 150 Khz- 30Mhz) conducted emi measurements are normally only required for those wires leaving equipment of which one may expect substantial length. This is true for mains wires, and miscellaneous types of network cables.
True due diligence however, may trigger a test procedure where signal lines which are known to be long due to the type of installation or other reasons,are being evaluated and their drivers possibly modified. We ran into such a situation where a roof mounted device was available in 2 variations, one mains supplied, and one 24 Vdc supplied. The earlier needed conducted testing, where the second did not. The mains supplied version had a mains filter, the 24 Volts version had not. One may imagine that the mains filter suppressed most of the conducted EMI (complied) and the 24 V version showed substantial interference on AM radio (due to an added SMPS and the omission of the filter) but was deemed to comply ALSO due to the absence of a conducted EMI test for DC supply ports. As the equipment was roof mounted, the supply cable was freely radiating harmonics of over 80 dBuV and interfering heavily with AM radio reception. On our suggestion customer re-inserted the same mains EMI filter in it's 24 V version , just to show due diligence. Regards, Gert Gremmen Manager Ce-test, Qualified Testing ce marking and more .. EMCD LVD R&TTED MDD MD www.ce-test.nl Electrical / Electronic Equipment -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Chris Maxwell Sent: Tuesday, April 23, 2002 7:24 PM To: EMC-PSTC Internet Forum Subject: Signal Line Emissions with Respect to EN 61326-1 Hi all, Recently, I have read quite a few threads regarding EN 55022 (European Emissions Limits for ITE equipment) and its newer requirements to measure signal line conducted emissions along with the typical power line conducted emissions. This caused me to go back and look at EN 61326-1:1998 (European EMC specs for Lab, Test and Measurement equipment) According to my copy of EN 61326-1, conducted emissions limits are only specified for "AC Mains". So apparantly, test and measurement equipment hasn't had this requirement placed upon it....yet. Does anybody know of any in-process amendments to EN 61326-1 that would add signal line conducted emissions? If so, is there any expectation of when the amendment is due to be processed? Thanks, Chris Maxwell | Design Engineer - Optical Division email [email protected] | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
