In message <c5557365.32493%ken.ja...@emccompliance.com>, dated Fri, 28 Nov 2008, Ken Javor <ken.ja...@emccompliance.com> writes:
>For instance, we control RE at three meters so that at typical BCB >reception levels, we have clear reception. That is EMC. If we move the >culprit emitter closer to the radio receiver than three meters we no >longer have a legitimate expectation of clear reception. Agreed: the effect of this distance factor is almost entirely not mentioned in EMC standards. > >With this sloppy terminology, rife in the commercial world, we are >raising a generation of EMC engineers who have no clue why they do what >they do, other than they have to meet some legal requirement before >marketing a product. Similarly with safety. >It is bad enough that I have seen in this forum otherwise well-regarded >engineers claiming that radiated emission requirements are there to >protect all electronics from interference, as opposed to radio >receivers, which are the sole victim protected by radiated emission >limits. That's not entirely true. IEC SC77C deals with immunity of the electrical infrastructure to high-energy phenomena, and one could consider the work on protection against lighting also to be EMC work. In addition, CENELEC has just started to look at the subject. A recent committee Minute reads: The committee considered the wording of a questionnaire to National Committees on the adequacy of current EMC standards for the protection of non-radio communication services [yes, that's ambiguous, but I think it means 'services other than radio communication services'], and agreed the content in principle. The committee has asked its Working Group to prepare the final wording, prior to circulation. >Non-antenna-connected electronics don?t require that level of >protection. That is generally true, but some medical equipment and scientific instruments are exceptions. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Either we are causing global warming, in which case we may be able to stop it, or natural variation is causing it, and we probably can't stop it. You choose! 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.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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
