Hello George, The 1000-4-6 is a test standard for immunity, by injecting current into the cables of the equipment. This current is defined by a voltage thought to flow through a 150 Ohms resistor. This resistance of which part is in the generator (50 Ohms) consists of N x 100 Ohms in which N is the number of UNSCREENED wires in a cable. The whole cable is well decoupled from the environment by a L/C filter. As this is a common mode filter one may wind the whole cable around a ferrite core, and add capacitors to ground at the cold site. To prevent short circuiting signal added common mode filters may be placed in series with the CAPS, so as not to attenuate the Differential signals and to let pass the Common mode RF current tha has to be decoupled.
Coupling mode of the injected current is thus in Common Mode, referenced to ground which is just a metal table top plate that the EUT is placed upon at 10 cm of height. Cable lengths from coupling/decoupling network (CDN) must be shorter then 30 cm. ( 12") running at average 3 cm height Not injected cables (if more then one) should be loaded with Nx100 + 50 Ohms, using the same type of CDN network, but no generator but load resistor. Any cable/ connector combination may require a separate type of CDN, and of every type of CDN you may need more then one part, to accommodate your EUT. Imagine our storage of CDN's as a test house !!! ;<) Several type of CDN are standard, and defined in the IEC 1000-4-6. To create 10 V of emf voltage at the EUT port (which is 5 Vrms in a 50 ohm system), you will actually need much more for the following reasons: - One requires 80 % AM modulation at 1 Khz, so actually 18 (9) Volt max. - As the load of the generator is 150 Ohms and it's output is 50 Ohm, a impedance adapting network (broadband) is required. To guarantee stability and flatness, most set ups use an 6 dB attenuator. As this att is not loaded with 50 Ohms, but with an average impedance of 100 + 150 Ohms, the voltage attenuation to the EUT ports is approx 2 times. To create 18 V emf here one needs 18 V of rms output at the amplifier, approx, 7 watts. output. Most of this will be dissipated in the 6 dB attenuator. At the output of the attenuator a voltage monitor is handy; one might consider using an 1 M oscilloscope probe using a BNC adapter jig on a T-bnc part , connected to an oscilloscope or spectrum analyzer. Please note that only 5/6 th of the voltage , so 15 volts is to be monitored here. This is a tricky thing, as no one guarantees the actual 150 Ohms average load, and the voltage here depends on this 150 ohms value ! If your amp is within 1 dB flat , consider just setting the output level. One should inject all cables in turn, while loading the others with 100 + 50 ohms. Other possibilities of current injection (EM-clamp) may be considered, but they require much more money, also because the 176 watt of power amp required. Current transformers can do the job too, if assisted with current clamps to verify the injected current. Please read the standard too ! Regards, Gert Gremmen Ing. == Ce-test, Qualified testing == Consultants in EMC, Electrical safety and Telecommunication Compliance tests for European standards and ce-marking Member of NEC/IEC voting committee for EMC. Our Web presence: http://www.cetest.nl List of current harmonized standards http://www.cetest.nl/emc-harm.htm 15 great tips for the EMC-designer http://www.cetest.nl/features01.htm -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Sparacino,George Sent: woensdag 16 december 1998 20:10 To: [email protected] Subject: IEC1000-4-6 ... Hello All, I'm looking for general design guidelines for meeting the 10V level requirement for conducted immunity on the power & I/O lines as specified in IEC1000-4-6.. I have not dealt with this requirement (yet) and would appreciate any design tips to help make my first experience a more pleasant one. If you know of any recent articles on this subject, please let me know. Thanks, George --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
