Could the ESD discrete signal be verified indirectly from measurement in the frequency domain with a spectrum analyzer before the advent of GHz oscilloscopes?
Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Monday, June 08, 2009 9:47 PM To: emc-p...@ieee.org Subject: Re: EN61326-1: 2006 In message <de87437fe365cb458c265ea3d73b6f1d04aa7...@xbc-mail1.xantrex.com>, dated Mon, 8 Jun 2009, Ralph McDiarmid <ralph.mcdiar...@xantrex.com> writes: >It would at least bring it into agreement with the requirements of both >the residential and industrial 61000 generic immunity standards. (4kV >contact, 8kV air) But, as Doug says, that is not a sufficient argument. Unless 4kV air can be shown not to be adequate to prevent an unacceptable number of field failures due to ESD damage, it should not be raised to 8 kV. There may be an explanation. We know that in cold northern countries, humidity can fall to 20% and below and a charged human body can reach a potential in the region of 15 kV. But this is rare, and 8 kV is considered sufficiently severe. Note 'considered': the only proof is 'epidemiological' - how many field failures occur? I suspect that most equipment to which IEC 61326 applies AND is exposed to ESD is used in air-conditioned spaces where humidity is kept at medium values and ESD voltages do not reach extreme values. There is a further issue. Until recently, the methods of verifying the output of ESD test hand-pieces were subject to considerable doubt and much controversy. To check the output waveform, oscilloscope bandwidths of at least 6 GHz are required, and these were very rare. So a lot of historical data were collected using test equipment whose characteristics are subject to significant uncertainty. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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...@socal.rr.com> 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...@socal.rr.com> 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...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
