Bob, Some immunity tests we perform with margin, some we do not. Surge test, for instance, we do not perform with margin because the most likely parts to fail are power supplies and other purchased primary components. If we test higher than is specified, and one of these components fail, we really can't do anything about it. Most companies test surge only to the required 2kV line to earth, 1kV line to line, but I know a couple companies that test up to 6kV because they can have hundrends of products installed in one location and a single surge can take them all out, so they design for 6kV. They are forced to specify their primary components to pass a 6KV surge test which make them non-standard components in most cases. Most companies can not take the price hit for such custom products. We test Burst at 2kV, Radiated Immunity to 10V/m, and Conducted Immunity to 10Vrms. Some of our products can be installed in or near industrial environments so we test higher which gives us margin for most of our standard installations. I will be interested in hearing other's comments on this. The Other Brian
_____ From: Bob Richards [mailto:[email protected]] Sent: Tuesday, June 26, 2007 1:54 PM To: Kunde, Brian Subject: Re: Internal Margins for Emissions Testing I've always heard that 6dB is a reasonable margin for conducted and radiated emissions. What I would like to know, does anyone test for margin with immunity? If so, how much margin? If not, why not? Bob Richards, NCT. "Kunde, Brian" <[email protected]> wrote: 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 _________________________ 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 email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- 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
