Good addition John, completely true.... I should have written "universal ground"
Gert -----Oorspronkelijk bericht----- Van: John Woodgate [mailto:j...@jmwa.demon.co.uk] Verzonden: zondag 22 december 2013 23:19 Aan: EMC-PSTC@LISTSERV.IEEE.ORG Onderwerp: Re: [PSES] EMC Puzzle update In message <FCA549BE3ECF9D4CB8CB8576837EA48920A450@ZEUS.cetest.local>, dated Sun, 22 Dec 2013, "ce-test, qualified testing bv - Gert Gremmen" <g.grem...@cetest.nl> writes: >Dirty planes do not exist, unless there is a reference to be compared >to, ideally universal ground. While most of what you say is true, there IS no 'universal ground', not even a conducting sheet, if it's bigger in any dimension than about 0.1 wavelengths, and, at lower frequencies, has a surface resistivity larger than that necessary to reduce the voltage between any two points to a negligible value. (What is negligible depends on signal levels, of course.) The case in this thread is that there was a separate 'chassis plane' in the stack. In terms of emissions, it's probably misleading to call it 'dirty', but for immunity, it certainly is dirty, because it introduces into the internal circuits stuff picked up from incident emissions. With seasonal greetings to all my readers. (;-) -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus 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 <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 <emcp...@radiusnorth.net> 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
