Monrad,
As one who used to work for a company that was BIG into fault tolerance (Tandem Computers) I understand your dual power cord model. And I agree that the likely scenario for a power failure would be a total loss of incoming power due to problems outside the site. Your scenario #1 looks like the case where a circuit breaker is tripped on the circuit feeding one of the inputs (I assume that your installation instructions say to feed the cords from separate circuits). For various reasons (best discussed on the phone as this message would get too long, otherwise) I would suggest that you continue as you have been, and add your 3rd option as well. All are legitimate operational scenarios for the test. It will add a little time, but would complete the picture. Ghery S. Pettit From: [email protected] [mailto:[email protected]] On Behalf Of Monrad Monsen Sent: Tuesday, March 10, 2009 4:57 PM To: [email protected] 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 [email protected] 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunitiesorg/emc-pstc 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[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.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[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.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
