Brian, I think the answers covered most of the topic quite well, but I have still something to add:
When you have to deal with modular systems (e.g. VME, CPCI, etc.) and you test individual boards within representative configurations, you want to have some margin, especially when you get one board for testing and you know that a customer wants to put 10 boards in one system. (This would be one answer to Patrick's first question) The same happens when you build a product which becomes part of a bigger installation sold by a customer. In this case the customer wants quite often to have some margin to ease integration EMC-wise. The reasons for the margin asked for are not always clear in this case, but when you are aware of it right from the start, much of it can be accomplished during the development without expensive shielding etc. Best regards, Michael Michael Nagel Senior EMC Engineer Motorola GmbH ECC Embedded Communications Computing Lilienthalstrasse 15 85579 Neubiberg/Muenchen - Germany Ph.: +49-89-9608-0 Fax: +49-89-9608-2376 e-mail: [email protected] info: http://www.motorola.com/computers Vorsitzender des Aufsichtsrates: Fred Irwin Geschäftsführung: Roland Duerr, Dr. Christoph Hollemann, Heinrich Korte, Ralf Gerbershagen (Vorsitzender) AG Wiesbaden, HRB 16024 VAT/USt.-ID: DE 113866163 From: [email protected] [mailto:[email protected]] On Behalf Of Kunde, Brian Sent: Dienstag, 26. Juni 2007 19:13 To: [email protected] Subject: Internal Margins for Emissions Testing Good people of the EMC-PSTC Group, I once again seek out your wisdom. We are an internal corporate EMC/Safety test lab. Most of the EMC testing we do are either Pass or Fail. But with Emissions testing (Radiated and Conducted) we want to pass with enough margin to insure our production stays compliant. The amount of margin that is accepted is always in debated between our department and engineering. I'm sure many of you have had similar problems. My question is how do you convey the desired margin on your test reports or other documents so the standard limits and internal limits (with margin) are properly documented and hopefully understood. Do you show two limit lines on your graphs an/or multiple limits and margins in your data tables? How does your Measurement Uncertainty factor into your data and how it is reported/documented? How are emissions requirements conveyed to engineering so they know what they are to design to (Limit plus some margin)? I know this seems like a newbie questions, but I am hoping that some of you have found cleaver new ways of dealing with this problem which has been around since the beginning of time. Thanks in advance for any and all replies, The Other Brian. LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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 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 ______________________________________________________________________
