I've seen it both ways. Some large manufacturers do not retest, preferring I suppose not to know if there is bad news. Another pulls a couple of units off the line every quarter and retests. Either way it is good practice to require some margin to the limits at the certification of initial samples to allow this and other variation in production.
In consumer electronics this issue becomes less prevalent as product life times are getting shorter and shorter. Gary Tornquist Director of Product Safety MICROSOFT [email protected]<mailto:[email protected]> Own Opinions Only From: Luke Turnbull [mailto:[email protected]] Sent: Thursday, July 11, 2013 2:35 AM To: [email protected] Subject: [PSES] Production Assurance Tests for EMC Dear Group, I have familiarity with how the aerospace and automotive industries deal with testing and manufacture of systems, but am less familiar with products tested to commercial standards. What is the custom and practice for demonstrating continued compliance to EMC requirements for products that are in production for a long time? I assume that over time, the construction of e.g. capacitors may change - leading to different stray characteristics, even for the same manufacturer and component value; and that IC's may be functionally similar, but again have a different internal construction. Do system suppliers generally re-test for EMC when components become obsolescent? Do system suppliers generally re-test periodically in case components have been unknowingly changed, or in case production processes have been changed without considering their effect on EMC compliance? Thanks for your help. Dr Luke Turnbull EMC Technical Manager TRW Conekt Stratford Road Solihull West Midlands B90 4GW United Kingdom Tel: +44 (0)121.627.3966 email: [email protected]<mailto:[email protected]> web: www.conekt.co.uk<http://www.conekt.co.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]<mailto:[email protected]>> 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://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]<mailto:[email protected]>> Mike Cantwell <[email protected]<mailto:[email protected]>> For policy questions, send mail to: Jim Bacher <[email protected]<mailto:[email protected]>> David Heald <[email protected]<mailto:[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.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://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]>
