The IEC 61000-4-6 standard allows for calibrations to be done into 300 ohm or 100 ohm loops (or 150 ohm & 50 ohm terminations). Using the 150 ohm termination, the calibration is done by leveling from the formula Um=U0/6. This is done with the 6 dB attenuator in place. Performing this calibration, determines the power levels necessary of the amplifier to achieve the voltage Umr. But in the test mode, using the BCI clamp as well as the 6 dB attenuator, the test is performed while monitoring with a current measuring probe to avoid over-injection. As you mentioned, the formula U0/150 ohms will limit the current.
So during calibration using the 150 ohm termination setup, the voltage measured Umr= U0/6, so for level 3, Umr =1.66 V. This would yield 33 mA of current across the 50 ohm resistor. But during test, Imax= U0/150 yields 66 mA of current. Regards, Rodger Gensel AR RF/Microwave Instrumentation _____ From: [email protected] [mailto:[email protected]] On Behalf Of Bob Richards Sent: Thursday, April 12, 2007 8:59 AM To: ieee 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
