I have a question for experts on details of Conducted Immunity testing per EN61000-4-3 using Current Clamp (NOT EM clamp) injection method.
I am reading BS EN61000-4-6, 1996 with Amendments 1 and 2. Section 7.2 (Procedure for clamp injection application) says that the Auxiliary Equipment (AE) impedance should meet the requirement from 6.2 as close as possible. Section 6.2 requires the input impedance (including the decoupling network - a line of ferrite in my case) to have the input common-mode impedance higher than 260 or 150 Ohm (depending on frequency). I can do it easily by lining the cable under test with ferrites on the AE-side of the injection clamp. Section 7.3 (Procedure for clamp injection when the common-mode impedance requirements cannot be met) states that "When using clamp injection and the common-mode impedance cannot be met at the AE side, it is necessary that the common-mode impedance of the AE is less then or equal to the of the EUT port being tested." While I can meet the input impedance requirement (>150 ohm) looking into the AE, the input common-mode impedance of the EUT port I have is much lower than 150 Ohm, on the order of 20-40 ohm. That is because at my EUT input I have center-tapped transformer, with the center-tap capacitively connected to GND, which is effectively a low impedance for common-mode. It seems that formally the section 7.3 doesn't apply for my device (because I can meet the AE-impedance requirement), but then I question why is it stated that it is important that the EUT input impedance (common mode) is higher than the AE input common-mode impedance only if the AE input impedance cannot be met. I believe it is important in any case. It seems I might likely overtest, because most current will flow into the EUT port. Am I out of luck, or can I use the clause of 7.3 which allows for measuring current into the EUT using a current-measuring clamp and limit the testing level to no more than I= Uo/150? I have a product that is allegedly failing (not by much) a 10 V level, and I want to be sure that it is being tested correctly (and not over-tested). Thank you very much, Neven This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
