In message <[email protected]>, dated Mon, 13 Apr 2009, "Kunde, Brian" <[email protected]> writes:
>John, > >I see your point and your position. I always appreciate your input. Thanks. > >I assure you I am not an EMC Crusader (I love that phrase, though). In >fact, I am a minimalist which gets me in trouble with the Accreditation >Crusaders :) You have my sympathy, but it won't help. > >The EMC Directive, Annex II (internal production control) point #8 >says, "The manufacturer must take all measures necessary to ensure that >the products are manufactured in accordance with the technical >documentation referred to in point 3 and with the provisions of this >Directive that apply to them." > >Note the requirement to assure compliance of what is manufactured, not >just a verification of the compliance of a golden unit. I also feel >that, "All Measures Necessary" does not mean test once than blindly >manufacturer forever. Indeed it doesn't. It's usually interpreted that each unit is subjected to simplified tests for major characteristics, e.g. measuring conducted common-mode instead of actual emissions on an OATS. The key point is that what is 'necessary' depends very greatly on the exact design of individual products, and it just isn't possible to do anything other than generalize. It may not even be 'design'. You specify the XYZ123 chip and your first 1000 units pass emissions with no problem. Then, without telling you, the manufacturer of XYZ123 does a die shrink, the chip get 30% faster and now there's a strong spectral line at 220 MHz that wasn't there before. > >All I am really saying is that it would be nice to have some set >guidelines for audit testing. It wouldn't have to be in a harmonized >standard. For me, I could go to my superiors with some documented >support for how much resources we should be spending on conformity >assessment. There are a few pages in the 4th edition of 'EMC for Product Designers' by Tim Williams, ISBN-10: 0-750-68170-5. But it's by no means a full treatment, and I would agree that there is an opportunity there for someone. > >With all the math involved in calculating Measure Uncertainty, there >should be something a lot less complicated to predict how often a >production product should be retested to insure compliance. The UK National Committee has proposed to IEC a project 'Guide to Uncertainty for Highly-Intelligent Dummies'. (;-) > -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. 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]>
