This is a response not only to Scott's message, but also in particular to Michael Sundstrom who wrote in a different posting, "...you might have V rms but not V/m in conducted immunity testing."
Conducted immunity testing of the bulk current injection or IEC 1000-4-6 type is a lumped element model of electromagnetic field-to-wire coupling and therefore there exists a direct relationship between the conducted stress (Amps or Volts) and the field intensity (V/m) which was responsible. For metallic platforms which route cable bundles a few centimeters above a ground plane, the conversion factor is 1.5 mA per Volt/meter at frequencies where the bundle electrical length is equal to or greater than a half wavelength. For cables run far from a poorly defined ground, as in a building, the conversion factor assumes a cable antenna factor of 1 with a source impedance of 150 Ohms (IEC 1000-4-6). This is a higher stress level than in the metallic platform case. This limit also assumes the cable is electrically long. Both coupling mechanisms become less efficient as the cable grows electrically short. For the case in point, an automobile, I assume the longest cable 5 meters. Five meters is a half wavelength at 30 MHz. Personally I am not aware of any requirements in the automotive world above 200 V/m, but I may be wrong on that as I haven't done any automotive consulting in at least five years. Based on 200 V/m, the bulk current injection limit would be 300 mA or 110 dBuA above 30 MHz, decreasing 20 dB per decade with decreasing frequency below 30 MHz. This is very much a worst case coupling assumption, since 1.5 mA per Volt per meter depends on plane wave illumination of a cable 5 cm above ground with the magnetic component of the field penetrating the loop formed by the cable above ground at right angles over the entire length of the cable run. For those who want to know, all of the analysis supporting the above statements is contained in a paper I presented at the 1997 EMC Symposium in Austin, TX. "On Field-To-Wire Coupling Versus Conducted Injection Techniques." Ken Javor on 1/10/02 7:41 AM, scott....@jci.com at scott....@jci.com wrote: > Ken and others, > > Yes, we have witnessed some very interesting deviations (as you may guess) > in product performance due to the intense RF Fields/Currents seen during > testing. Our designs are impacted by this test on a regular basis. We > would definitely entertain the idea of making the requirement more > reasonable, to better represent the vehicle environment. > > > Regards, > > Scott > > > > > > ken.javor@emccompliance > .com To: scott....@jci.com, > emc-p...@majordomo.ieee.org > Sent by: cc: > owner-emc-pstc@majordom Subject: FW: ISO 11452-4 Bulk Current > Injection Test Requirements > o.ieee.org > > > 01/09/02 04:40 PM > Please respond to > ken.javor > > > > > > > > Scott and other EMC engineers, > > I looked up the referenced spec and saw it was an AUTOMOTIVE spec. And the > injection level is near CONSTANT from 1 - 400 MHz, with an injection level > as high as 1 Amp at the low end (1 - 30 MHz). Keith Armstrong, pay heed. > The unalterable physics of field-to-wire coupling predict that this limit > implies a field intensity of at least 700 V/m up to 30 MHz and at least 150 > V/m and the vehicle is over 100 m long. If there are any design impacts to > meeting this requirement (and I am sure there are when every penny counts) > this spec is massive overkill and needs to be completely revised. > > Ken Javor > ---------- > From: Ken Javor <ken.ja...@emccompliance.com> > Date: Wed, 09 Jan 2002 16:23:21 -0500 > To: <scott....@jci.com>, <emc-p...@majordomo.ieee.org> > Subject: Re: ISO 11452-4 Bulk Current Injection Test Requirements > > Scott, > > I am not familiar with the standard you cite, but am quite familiar with > BCI > testing in general and the equipment used specifically. The injection > clamp > used to 400 MHz is only good to 400 or 450 MHz, depending upon > manufacturer. > The current probe used to monitor CUT-injected current will either be good > to 450 MHz or 1 GHz. To my knowledge, there are no current probes in > general use above 1 GHz and measurement of current on an unmatched > transmission line (the CUT) becomes quite problematical even at 400 MHz. > So > my answer, not authoritative in a specification sense, but based on the > physics of the situation and the test equipment available is that you > control harmonics up to 400 MHz, and don't try to measure beyond that. > > P.S. You should have no such problems regardless. The harmonic problem is > an issue when you are at the very low end of the frequency range of an > injection clamp and it is more efficient at the harmonics than at the > fundamental. The high power tube amps used up to 220 MHz do have high > harmonic content (-16 dBc), but you should be able to use a lower power > solid-state amp with better performance, and in any case you have an easy > out. There is a clamp that covers 0.01 - 100 MHz and another that covers 2 > - 400 MHz. If you use the lower range clamp to 10 MHz or thereabouts you > can > start using the upper range clamp at a frequency where its insertion loss > is > flat with frequency. The lower range clamp is flat from below 1 MHz and on > up. > > Ken > > > > > on 1/9/02 2:41 PM, scott....@jci.com at scott....@jci.com wrote: > >> >> To All, >> >> We are performing BCI testing according to the test method described in > ISO >> 11452-4 (Test Range 1MHz - 400MHz) >> >> We are unclear on the statement described in Section 3 - "Test > Conditions" >> regarding measuring the harmonics. >> The standard indicates that if a deviation in product performance occurs, >> the first 5 harmonics (relative to the carrier) must be measured. These >> harmonics must not exceed -9dBc. >> >> Here's where my question originates... The standard says "...it must be >> ensured that any of the first five harmonics (up to 400MHz) shall not >> exceed - 9dBc relative to the fundamental frequency....." >> >> >> I am looking for help with interpreting the text in the specification. >> >> >> 1. Does the text indicate that only harmonics with frequencies from 1 - >> 400MHz should be considered (carrier frequencies less than 80MHz)? >> >> 2. Does the text indicate that harmonics up to 2GHz (400MHz is the > highest >> test frequency - multiplied by 5 harmonics = 2GHz) SHOULD BE MEASURED.? >> >> 3. other? >> >> Any help would be greatly appreciated. >> >> Thank you. >> >> >> Regards, >> >> Scott Mee >> EMC Engineer >> >> Johnson Controls Inc. >> PH: 616.394.2565 >> EMAIL: scott....@jci.com >> >> >> ------------------------------------------- >> This message is from the IEEE EMC Society Product Safety >> Technical Committee emc-pstc discussion list. >> >> Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ >> >> To cancel your subscription, send mail to: >> majord...@ieee.org >> with the single line: >> unsubscribe emc-pstc >> >> For help, send mail to the list administrators: >> Michael Garretson: pstc_ad...@garretson.org >> Dave Heald davehe...@mediaone.net >> >> For policy questions, send mail to: >> Richard Nute: ri...@ieee.org >> Jim Bacher: j.bac...@ieee.org >> >> All emc-pstc postings are archived and searchable on the web at: >> No longer online until our new server is brought online and the old > messages >> are imported into the new server. >> > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > > > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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