I'm afraid that one cannot assume that our ancestors were either all-knowing or idiots. They were people, just like us, and they got it right mostly, but not always.
With best wishes DESIGN IT IN! OOO - Own Opinions Only www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England UK is a sovereignty, not a Zollverein-ty -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Tuesday, September 12, 2017 12:37 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] LISN Calibration Measurement Uncertainty Perhaps all that is needed is to know is the Insertion Loss of the LISN. Some manufacturers provide this for every s/n. The LISN is only there to provide a known impedance to the source of emission so that RF current can be measured with repeatability. I do understand that CM and DM currents will have different (and unknown) source impedance and that those impedances will be a function of frequency, but I feel that's beside the point. I have to assume the folks at CISPR understood those topics and that they likely deliberated long and hard and did lots of measurements both in the lab and in the field before agreeing on the LISN as a standard transducer for the evaluation of conducted RF emission. If there were something fundamentally wrong with the method of measurement, I suspect it would have been uncovered long ago. Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Monday, September 11, 2017 4:10 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] LISN Calibration Measurement Uncertainty The point of the cm vs. dm discussion is that the effect of LISN impedance is not so important for dm as for cm, speaking very generally, so that the effect of uncertainty in LISN impedance on dm emissions is less than for cm. But we don't separately measure cm and dm, so we don't know, looking at any specific signal, what the uncertainty is, even if we have nailed down the uncertainty of the LISN impedance. And you don't need two LISNs to separate modes, but that is another discussion. Ken Javor Phone: (256) 650-5261 - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
