No disagreement with John but keep in mind that even the best test houses occassionally have unexpected problems with equipment so don't dismiss the possibility that their equipment isn't malfunctioning. They shouldn't have any real problems with verifying the operation. Over the years I've had a handful of situations like that and the test house is as anxious as your are to confirm good equipment and practices. Gary
From: [email protected] [mailto:[email protected]] On Behalf Of John Woodgate Sent: Friday, December 09, 2005 3:02 AM To: [email protected] Subject: Re: Problems with surge testing "White, Ian" <[email protected]> wrote (in <DE5AB3E5A2E9D6119B0F000802B2762630F335@UKCHEEX01>) about 'Problems with surge testing', on Fri, 9 Dec 2005: >Is there any way l can check the performance and set up of my surge >signal test equipment. I use a Schaffner Best EMC working in Surge >signal mode and a Schaffner CDN 117. > >The Schaffner has only just been calibrated but l am not getting the >same results from it, that a local test house obtained while testing >one of our products. Two general points: - If you have a question about a test gear product that is still supported by the manufacturer, ask the manufacturer first; - There is a LOT of uncertainty (and another, distinct phenomenon called 'variability', which IEC SC77A has had to introduce) in EMC measurements. You must EXPECT the results from tests done: - at different times, and/or - with different test equipment, and/or - on a different sample, and/or - at a different location, to vary. What matters is whether any of the test results show that the product does not pass the tests. Other differences may need explaining, and maybe some corrective action, but they are not in themselves of vital importance. -- Regards, John Woodgate, OOO - Own Opinions Only. Deadlines are 90% of deadliness. http://www.jmwa.demon.co.uk Also see http://www.isce.org.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 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
