You are right, as always, but for this specific subject, where a strictly (designed) 2 input line circuit (SMPS) creates a common mode current (implying a 3rd conductor) (be it earths, zero reference, enclosure or whatever), the term "real earth" may be sufficient accurate.
Take a look at most functional designs diagrams, I never saw an enclosure ground drawn, or an estimation of the parasitic caps, and any effort to cancel out there effects, but by brute force (EMC filter, however effective they may be) And where a 3rd conductor was designed, (enclosure, ground or whatever name), it was there for EMC or for Electrical safety: - as a center tap for Y caps (EMC: makes this discussion superfluous) - as Protecting earth for Electrical safety Regards, Ing. Gert Gremmen ce-test, qualified testing bv Van: [email protected] [mailto:[email protected]] Namens John Woodgate Verzonden: Monday, December 22, 2008 2:11 PM Aan: [email protected] Onderwerp: Re: Thevenin equivalent circuit for SMPS emission sources - issues In message <[email protected]>, dated Mon, 22 Dec 2008, Gert Gremmen <[email protected]> writes: >All designers (but the RF specialists) overlook the third connection to >any circuit , the real earth ! (sometimes represented by a conductive >enclosure) There is no such thing as 'real earth'. There are only purely local 'zero reference potentials'. I gave a talk on this recently to the UKRI section, and I'm trying to get time to write it up for the section web site. At 3 GHz, 'local' usually means 'REALLY local' (millimetres, even). At mains frequency, significant voltage differences can occur between points not many metres apart. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk All these closing-downs have been caused by dozing clowns John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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]>
