HI Monrad – I think I see your point. The idea for redundant power is to provide (as Ghery says) fault tolerance so internal building power issues are mitigated. Scenario 3 is an extreme – but possible - case. As long as Sun
does not advertise fault tolerance during a Scenario 3 case – then I wouldn’t test for it. The spec does not provide guidance in this matter – rather the CE mark is intended to show that you (the manufacturer) meet the advertised performance of the product you are putting on the market. Chas ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Monrad Monsen Sent: Tuesday, March 10, 2009 5:57 PM To: emc-p...@ieee.org Subject: IEC61000-4-11 for Products with Redundant Power Is there anything in IEC61000-4-11 voltage dips & short interrupts standard that gives guidance on how a product with redundant power should be tested? In testing, we have always tested the product in two configurations: 1. One cord to dip/interrupt generator, the other cord to a steady power source. (Criteria A) Note: This condition shows that the redundancy works appropriately. 2. One cord to dip/interrupt generator, the other cord unplugged (no power). (Criteria as listed in EN55024) However, for those products that always are sold with power redundancy, the power supply designers working in constrained small packages have asked if we would not test with condition #2 but instead test in the condition #3 below. 3. Both cords going to power strip that is connected to the dip/interrupt generator. Both cords experience the immunity phenomena simultaneously. (Criteria as listed in EN55024) In defense of condition #3, the power supply designers point out that generally a power interrupt would occur from the power company to affect all cords, and it is not a normal configuration to not plug in both power plugs of a redundant power system. They like this approach because two power supplies would give the benefit of nearly double the holdup time before the product shuts down. Hence, I am looking for guidance in the standards on what the correct approach is for testing systems with redundant power. Thanks. -- Monrad L. Monsen Compliance Program Manager Sun Microsystems monrad.mon...@sun.com 303.272.9612 Office - 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 <emc-p...@ieee.org> 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 <emc-p...@ieee.org> 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 <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
