I tend to over react to huge open-ended questions. So, following text shall be consumed with several grams of a non-polyatomic binary ionic compound that is not a SVHC substance, or is listed in RoHS or JIG101 (CAS 7647-14-5) - just shoot me...
I do not understand "optimum" type test condition. The term "standard outlet" is not defined in IEC60950-1 other then for an ac outlet included in the equipment. I do not remember the term "typical circuit breaker" in BS7671. I do not remember any "standard outlet" defined in NFPA70 or NFPA75. The least favorable test condition is delimited by of the test standard description and the environment defined by the local electric code. The least favorable type test condition should be determined by the power supply designer and the NCB/NRTL/CBTL. The end-user can only guess at the least favorable type test condition for a purchased power source. About the test facility - a lab doing IT equipment safety tests should have, as matter of 'standard', 1000A peak fault current available. There is no reason to believe that a 1000A peak fault current will always open a 40A distribution breaker. If the wall-wart adapter is a switching power source, and you are having over 100A of fault current - find another supplier. If the wall-wart adapter is a linear power source - find another supplier, or ask for a more recent design that will meet the new efficiency requirements. Performing type tests on an incomplete construction is disallowed in 60950-1. I do not know if it is "common practice", but when I test a wall wart power supply, new plastic is assembled for each fault condition. I am not that familiar with BS7671 or BS1363, so will not comment - but suffice to say that these people have written some serious requirements for plugs and cords - read these standards. Finally, pluggable equip type B should never apply to a wall wart; and we have this little gem in 2.7.1 - "NOTE In the member countries of CENELEC, the protective devices necessary to comply with the requirements of 5.3 must, with certain exceptions, be included as part of the equipment." From: [email protected] [mailto:[email protected]]On Behalf Of Mark Gandler Sent: Monday, May 18, 2009 5:14 PM To: [email protected] Subject: IEC 60950-1 short circuit test criteria Hi, I would like to get your opinion on the test conditions applicable for sections 2.7 and 5.3, primarily for short circuit test. Let's assume it is direct plug-in equipment/AC-DC power adapter. What will be most appropriate power source requirement for performing s.c. test for UK ring? I can find the source which can go as high as 900A while shorted on the primary side and can adjust the phase (which we found at 0 degrees it has the highest effect). Assuming product is going to relay on building installation for backup protection. I would like to get opinions and examples on what would be considered optimum and worst case scenarios. Do you think it is reasonable to expect lab in China or US could adequately represent real life conditions let's say of the power ring in UK? We observed failures just by plugging in short circuited equipment in the standard outlet which could not be reproduced in the lab. what is the common practice for abnormal testing for ultrasoncly welded adapters? do you cut a window then reaseal it, do you test just open PCB? what is the typical circuit breaker in UK? 32A? does every outlet has build in 13A fuse? Last but not the least question: could you please recommend reliable brand name 60950 Safety Lab in UK? (would not hurt if near London)? Thanks a lot for any advise Mark Gandler - 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]>
