The rationale for specifying the open circuit potential is at least partly due to the fact that the source impedance is 150 Ohms, not the 50 Ohms of the test equipment source. Also, there is then a cleaner relationship between the stated conducted stress and the radiated field to which it is related, namely 1:1.
The second question is about current drive. The specified Uo/150 is the current Uo with a 150 Ohm source impedance can drive into a dead short, which is what a tabletop shielded cable looks like. This value is twice the current that would be delivered into a matched 150 Ohm load. From: Bob Richards <[email protected]> List-Post: [email protected] Date: Thu, 12 Apr 2007 05:58:57 -0700 (PDT) To: ieee <[email protected]> Subject: Questions on 61000-4-6 conducted immunity I've been doing some research on the IEC 61000-4-6 standard, and have a couple of questions that hopefully someone here can answer. What is the rationale behind specifying the test level as Vemf (open circuit voltage)? The calibration is actually done to 1/2 the test level since the calibration fixture is terminated. When performing clamp injection according to section 7.4, the injected current is monitored and limited by the formula Imax = Uo/150. Since the test level Uo is specified as an open circuit voltage, and the terminated calibration level is 1/2 Uo, would this not allow the EUT to be overtested by 6dB? Bob Richards, NCT. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
