While I had nothing to do with any CISPR limit setting or test methods, it seems intuitively appealing that the 80 MHz demarcation between conducted and radiated immunity is based on the efficiency of the biconical antenna, or any similarly sized antenna:
Ken Javor Phone: (256) 650-5261 From: "Ghery S. Pettit" <[email protected]> Reply-To: <[email protected]> Date: Thu, 25 Mar 2021 17:29:40 -0700 To: <[email protected]> Subject: Re: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6 Jeff, I¹m not sure what the technical rationale was back when CISPR 24 was originally published (yes, the 3 V limit dates back to then) but as I recall the idea was that above 80 MHz you could generate a uniform field and below 80 MHz this was far more difficult. Why 80 MHz? Because it was convenient (as best as I recall). When we wrote CISPR 35 the thought was that 3 V/m resulted in a lower voltage than was tested to in CISPR 24, so the limit was lowered. The test levels called out in IEC 61000-4-6 have no bearing on the levels actually called out in CISPR 35. The same goes for radiated immunity above 80 MHz. The IEC 61000-4-x documents are called out as test methods, the test levels are called out in the product family standards, in this case CISPR 35. If you (or the client) feel that the test levels are wrong I would suggest that you join the US CISPR I TAG and make your concerns known. Contact me privately and I¹ll be happy to provide you with the email address of the US Technical Expert who will (I¹m sure) be happy to have you join the TAG. I hope this helps. Ghery S. Pettit Chair, CISPR SC I From: Jeff Keyzer <[email protected]> Sent: Thursday, March 25, 2021 10:21 AM To: [email protected] Subject: [PSES] rationale behind conducted immunity levels in EN 55035 / IEC 61000-4-6 Hello all, I am looking for background information on the rationale behind the conducted immunity test levels defined in EN 55035 / CISPR 35 and IEC 61000-4-6. Specifically, in 55035:2016 table 2, clause 2.1 calls for a test level of 3V rms from 0.15 to 10MHz. It also defines a slope that reduces the signal level above 10MHz. What is the technical rationale behind 3V rms being the desired immunity level for ITE equipment? Second, why does the voltage level taper above 10MHz in 55035, as opposed to 55024, where the test remains constant from 150kHz - 80MHz? IEC 61000-4-6 also calls for 1V, 3V, 10V rms test levels and calls for 80% AM modulation "to simulate actual threats". Is the rationale behind this documented somewhere? What threats were considered? I suspect this is a rabbit hole, but curiosity (and a concerned client) has gotten the best of me. -- Jeff Keyzer MightyOhm LLC [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.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) <http://www.ieee-pses.org/list.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.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) <http://www.ieee-pses.org/list.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.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]>
