HI Ralph, Nice "out of the box" thinking, however, I suspect spectrum analyzers in those earlier days would have had issues in capturing all components of the frequency spectrum of a pulsed signal. Just a guess, though.
Regards, Ken Wyatt Technical Services, LLC 56 Aspen Dr. Woodland Park, CO 80863 Email: [email protected] Web: www.emc-seminars.com LinkedIn: http://www.linkedin.com/in/kennethwyatt (719) 310-5418 On Jun 9, 2009, at 9:52 AM, Ralph McDiarmid wrote: > 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 > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of John > Woodgate > Sent: Monday, June 08, 2009 9:47 PM > To: [email protected] > Subject: Re: EN61326-1: 2006 > > In message > <[email protected]>, > dated > Mon, 8 Jun 2009, Ralph McDiarmid <[email protected]> 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. 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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]>
