In message <[email protected]>, dated Thu, 28 Jun 2007, Gary Stuyvenberg <[email protected]> writes:
>In reference to your first comment, can you explain this further? That >sounds like circular reasoning to me. Does not the EMC Directive take >precedence and set the tone for the standards? I don't think I understand the question. The Directive just has two Essential Requirements: - not to cause interference, and - not to be unduly sensitive to it. The standards do not say 'no emissions' and 'infinite immunity'; they obviously set what a majority, at least, of the relevant national standards committees consider reasonable, practicable and economically supportable. > >Responding to your second comment, it was assumed any other products >experiencing interference were compliant. Also, by performing immunity >testing at specific distance and field strength, are you not defining >encroachment limits for your product? Again, I'm not sure what you mean. A test distance of 3 m should not be assumed to mean that below 3 m interference is certain. The test level is set higher than that. On the other hand, it isn't set so high that interference at 10 cm cannot occur. What you can't do is to calculate from the emission limit and test distance, and the immunity limit, the separation below which interference is inevitable. This is because many external factors influence the field strength at any point. A calculation would be valid in free space, provided the result gave a distance in the far field of the source. But not otherwise. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
