You are right John, for low frequencies.
For everything above audible frequencies do not worry about ground loops inside enclosures , but make them small to increase any resonance frequencies above the range of problems. (PCB low above Chassis, many stud grounding points, not just 4 on a 4" x 6" PCB) Regards, Ing. Gert Gremmen [email protected] www.cetest.nl Before printing, think about the environment. -----Oorspronkelijk bericht----- Van: [email protected] [mailto:[email protected]] Namens John Woodgate Verzonden: Thursday, September 30, 2010 10:29 AM Aan: [email protected] Onderwerp: Re: [PSES] EMI issue with Ethernet In message <[email protected]>, dated Thu, 30 Sep 2010, deepak Engineer <[email protected]> writes: >In whole system, Chasiss ground and signal ground are >linked/communicating through only two points.. >1. throught zero ohms resistor between RJ45 jack and signal ground >2. through chassis, where ethernet cable ground will be passed to >chassis(thru mounting hole) and mix with singal ground... > >would it effect the system... >is it stable approach.. > The best technique is to have only one point of contact, like your item 1. If you have two points of contact you have created a low-impedance loop and all the local magnetic fields induce large currents in such loops. This means that points on the loop are NOT at the same potential - you don't have an equipotential 'ground' any more. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK If at first you don't succeed, delegate. But I support unbloated email http://www.asciiribbon.org/ - ---------------------------------------------------------------- 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]>
