Thanks David for bringing that detail into focus. Edition 2 writes about "unwanted voltage drops from coupling/decoupling networks", while Table 6 allows for a shorter front time for higher line currents, presumably to reduces impedance required by the decoupling network ( a smaller inductance). I think that's right because of the 10% voltage drop limit stipulated in clause 6.3.1. At some point, the impedance of the decoupling network becomes so small, (Z=Vdrop/current), it can no longer effectively decouple the surge wave front, and so less surge energy gets coupled into the EUT port. For line currents in excess of 100A, the standard goes all the way to allow testing a non-powered EUT, and so no decoupling network burden.
Perhaps large EUTs (those rated > 100A) can be left powered at 100A for a "live" test. I don't know if that's better than a de-energized EUT with no decoupling load burden. Partial testing of large EUT (e.g. testing the control circuits alone) seems inadequate, but a diligent discussion in a Technical File could accompany the test results. Some assessors might have trouble with the arguments though. There is lots of "grey". _______________________________________________________________________________ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: "Schaefer, David" <[email protected]> To: [email protected], Date: 08/21/2015 12:30 PM Subject: Re: [PSES] Different surge test equipment, different results Peter, Are the open circuit waveforms identical out of the surge generator, or out of the coupling decoupling network? -4-5 relaxes the waveform limits for the rise time and duration at the output of a CDN, based on amperage. Check out tables 6 and 7 of the 2nd Edition for more information. Two generators should produce identical waveshapes out of the generator itself, but the CDNs could have drastically different durations. Thanks, David Schaefer EMC Chief Technical Advisor TÜV SÜD America Inc Office: 651 638 0251 Cell: 612 578 6038 Fax: 651 638 0285 -----Original Message----- From: Peter Tarver [mailto:[email protected]] Sent: Friday, August 21, 2015 1:51 PM To: [email protected] Subject: [PSES] Different surge test equipment, different results Good morning. I'm wondering if others have experienced cases where different manufacturers' surge test equipment (ANSI/IEEE C62.41 ring and combination waves) with nearly identical open-circuit voltage and short-circuit current calibrations have led to very different results. In these cases, other than addressing the issue by using the surge generator that produces the worst-case result, what were thought to be the causes for the different results (ignoring the real possibility of a marginal design). Regards, Peter L. Tarver - ---------------------------------------------------------------- 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.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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 email has been scanned by the Symantec Email Security.cloud service. ______________________________________________________________________ - ---------------------------------------------------------------- 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.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
