Doug,
Thanks for the explanation. If for example a capacitor is hit several times with a surge pulse of the same polarity, I believe it will be less stressed than when each consecutive pulse is of different polarity. When changing polarity, that capacitor must discharge first to 0 and will then be charged with the new pulse of the alternative polarity. I think the same phenomenon happens when just insulation is stressed with alternating polarities. Also the inrush surge current will be higher when testing with alternating polarities. I agree with you about the example of the 2 bipolar devices, then using 5 pulses of the same polarity will indeed be worse. I don’t understand why you say that an automated test system would be able to minimize test time when using polarities of the same kind. I would say that this depends just on how you program the test equipment. Fact is however that IEC61000-4-5 doesn’t specify the sequence while K.44 does with alternating polarities. And both standards are also meant for testing the same (AC mains) interface… Kind regards, Kris Carpentier Regulatory & Approvals From: [email protected] [mailto:[email protected]] On Behalf Of Powell, Doug Sent: woensdag 23 september 2009 16:51 To: EMC PSTC Subject: RE: IEC61000-4-5 reversed polarity or not All, I consider ten consecutive pulses of the same polarity as worst case. One reason for this is the possibility of some products accumulating charge between pulses. By alternating the polarity on each pulse, you theoretically “reset” any accumulated charge which has not returned to zero. Although I was not privy to committee discussions in this respect, I believe this may be part of the reason. Then again, it may be a simple question of expediency. Most automated tests I see do their best to minimize total test time by repeating tests in a single configuration many times (phases, polarity, angle). Alternating polarities would mean manual testing and is very inefficient for three phase products, which receive a minimum of 480 pulses. Also, if you use any bi-polar clamping devices such as MOVs, gas discharge tubes, or TSBs. These devices accumulate heat and if they are not sized appropriately to dissipate the energy seen in a series of pulses may cause them to fail. If for example, your design uses two uni-polar TSBs in an anti-parallel configuration and you alternate polarities, the total heat accumulation in each stage of the test is shared by both. By pulsing in one polarity at each stage, you are exercising only the one device which could then overheat if not sized correctly. -doug Douglas E. Powell Advanced Energy Industries, Inc. From: [email protected] [mailto:[email protected]] On Behalf Of Doug Kramer Sent: Wednesday, September 23, 2009 8:12 AM To: EMC PSTC Subject: RE: IEC61000-4-5 reversed polarity or not Kris, In my experience most follow the “+++++ then -----” pattern. We currently do and it is the way that at least 3 different automation software packages setup the test for 61000-4-5 by default. -Doug From: [email protected] [mailto:[email protected]] On Behalf Of Carpentier Kristiaan Sent: Wednesday, September 23, 2009 8:49 AM To: John J Radomski Cc: EMC PSTC Subject: RE: IEC61000-4-5 reversed polarity or not John, Cl 6.1.1 says “positive & negative” but not between consecutive pulses. I ask because some labs do testing +++++ then -----. Kind regards, Kris Carpentier Regulatory & Approvals From: John J Radomski [mailto:[email protected]] Sent: woensdag 23 september 2009 15:42 To: Carpentier Kristiaan Cc: EMC PSTC Subject: Re: IEC61000-4-5 reversed polarity or not Hi Kristiaan, > Is it common practice to reverse polarity in this standard as well? Yes it is. This can be found in Cl. 6.1.1. Regards, John "Carpentier Kristiaan" <[email protected]> Sent by: [email protected] 09/23/2009 09:22 AM To "EMC PSTC" <[email protected]> cc Subject IEC61000-4-5 reversed polarity or not Hi group, The lightning protection standard ITU-T K.44 clearly states that the polarity of the surges shall be reversed between consecutive pulses. IEC61000-4-5 does not state that requirement. Is it common practice to reverse polarity in this standard as well? Vriendelijke groeten, meilleures salutations, mit freundlichen Gruessen, best regards, Kris Carpentier - 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]> - 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, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. - 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]>
