All, Mr. Chileshe's response elicits one further comment. Although Mr. Price's customer called out EN61000-4-6 for an equipment to be installed on a passenger bus, and the customer is always right, at least in a good business sense, technically a requirement like MIL-STD-461 CS114, or the automotive equivalent makes a lot more sense. The reason for this is that the assumed transfer function from a radiated field to a coupled conducted stress is different between EN61000-4-6 and the automotive or military/aerospace "equivalents."
In fact the issue is not between commercial requirements and military or automotive, but between requirements based on the presence or absence of a well-defined ground plane. EN61000-4-6 is based on the absence of a ground plane, while MIL-STD-461, RTCA/DO-160, SAE J1113 and DEF-STAN 5941 are all based on the presence of a ground plane. And yes, EN 61000-4-6 requires a ground plane for the test, but that in no way alters the fact that the transfer function between field and coupled stress assumes the cable is an antenna, whereas the other standards mentioned assume the cable is a single wire above ground. Here is the math. Mr. Price's customer required a 20 Volt limit. Recall that this means 20 Vrms, open circuit, from a 150 Ohm source impedance. The 20 Volt limit means the assumed radiated field intensity impinging on the cable to cause the coupling is 20 Volts per meter (from the levels in 61000-4-3 compared to the same classes of equipment in 61000-4-6). The source will deliver 1/15 Ampere into a matched load. Compared to the assumed 20 V/m field, the transfer function is 1/300 Ampere per Volt/meter, or 3.3 mA per Volt/meter. That compares to 1.5 mA per Volt/meter for all of the platform based requirements. Also the driving potential for the platform-based requirements and a 20 V/m field would be on the order of 6 Volts open circuit, instead of 20. Ken Javor Ken Javor From: "Chileshe, Chris" <[email protected]> List-Post: [email protected] Date: Wed, 22 Feb 2006 09:30:57 -0000 To: "Ken Javor" <[email protected]>, <[email protected]> Subject: RE: EN61000-4-6:1996 Ken, You are absolutely right. I was not trying to put forward the audio frequency noise immunity test as a possible alternative to the CI test. I was drawing attention to the possibility that the wrong set of standards might have been called out, and should the customer choose to go the ISO route, might find themselves applying a new set of standards - most of which will have been cited in 2004/104/EC (ESD, supply line transients etc). For a passenger vehicle, it might be worthwhile assessing the suitability of the audio-frequency noise immunity test. In the event that the customer has indeed applied the wrong set of standards, then the likelihood they could miss this test altogether is high. Rgds - Chris From: [email protected] [mailto:[email protected]]On Behalf Of Ken Javor Sent: 21 February 2006 16:33 To: [email protected] Subject: Re: EN61000-4-6:1996 A couple comments. A strip line test might be a substitute for an rf conducted immunity test, if the stripline were long enough to illuminate the entire cable harness, which is at least within the realm of the possible for equipment slated for placement on a passenger bus. The 15 cm stripline height is commensurate with a CI requirement which stops at 80 MHz. However the audio frequency CI test mentioned below has nothing whatever to do with the original rf CI requirement mentioned by Mr. Price. The audio CI requirement is a differential mode test meant to simulate power-quality-related electrical bus ripple potential, whereas the rf CI requirement is common mode and reflects a concern with intentional rf transmissions coupling to cables within the passenger bus. From: "Chileshe, Chris" <[email protected]> List-Post: [email protected] Date: Tue, 21 Feb 2006 16:18:17 -0000 To: <[email protected]> Subject: RE: EN61000-4-6:1996 Ed, I'll state right the outset that this e-mail does not answer any of your questions. I am only commenting on the test request. It really sounds to me like your customer wants to perform the automotive equivalent to the conducted immunity test of EN 61000-4-6. The ideal candidate for the frequency range (presumed 150kHz to 80MHz) is the stripline test of ISO 11452-5. The severity test levels can be correlated with free-field according to Annex B of this standard (correct for 150mm stripline) I prefer the Bulk Current Injection (BCI) test method of ISO 11452-4 for equipment in plastic enclosures for reasons of the effects of fringe fields from stripline plates near the EUT. Unfortunately, the ISO standard specifies a 1MHz lower limit on the frequency range. Applying the ISO 11452 group of immunity standards offers your customer compliance with the radiated immunity requirements of automotive directive 2004/104/EC. Another test that could apply is the audio-frequency coupled noise immunity test of SAE J1113 SEP96 Sec 2 specified for 30Hz to 50kHz. The worst severity level I have received in a customer specification is 3V pk-pk for a piece of equipment specified for 100V/m immunity ( free-field). I just wonder if this is a case of the wrong standards - albeit more "familiar" ones - being applied to a product. Rgds - Chris O.O.Only. From: [email protected] [mailto:[email protected]]On Behalf Of Price, Ed Sent: 21 February 2006 15:13 To: [email protected] Subject: EN61000-4-6:1996 I have been asked to do a Conducted Immunity test per BS EN61000-4-6:1996 on a gadget that mounts on the inside wall of a bus (and is accessible to the passengers). First, I think this isn't the latest version of this specification, but it is what the customer requested. This device has a completely non-conductive outer case. The only conductive point is on it's rear, where a 15-pin "D" connector supplies vehicle power through a shielded, twisted-pair cable. The customer asked for a "direct connection" test, as shown in Figure 2a, with a test level of 20 Volts. It seems to me that I will need to be able to generate about 100 Vpp and 200 Watts from my RF amplifier. Does the requested test level seem a bit extreme for a passenger bus application? Further, I don't understand how to measure the voltage Uo. Is this the voltage across the output of my 50-ohm RF source, or the voltage from the test specimen injection point to ground? And finally, Figure 2a implies a conductive test specimen case. How do you do this test for a non-conductive case, where the only conductive surface available is the length of the shielded power cable? I'd appreciate any comments or guidance. Regards, Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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