I am quite familiar with 61000-4-6. But it is an immunity requirement and has nothing to do with the current thread, which is about controlling cm EMISSIONS on cables.
I suppose one could use a CDN designed for injection as a measurement tool, but the absorbing clamp is so superior - it can be used on all types of cables, and it works up to 1 GHz, whereas CDNs are designed for no more than 230 MHz. The fact that the CDN works well below 30 MHz, all the way down to 150 kHz is immaterial - RE requirements start at 30 MHz, and in any case the absorbing clamp makes a superb current probe at 150 kHz - anyone wanting a transfer impedance for that device let me know. For those interested, my website includes a quite complete discussion on the pros and cons of using conducted techniques to simulate radiated immunity coupling, with a discussion of the corresponding emissions discussion in the introduction. Go to www.emccompliance.com, push the EMC INFO button, select the download page, and skip to the last selectable item, which is a paper I presented at the '97 IEEE EMC show in Austin, "On Field-To-Wire Coupling Versus Conducted Injection Techniques." Ken Javor ---------- >From: "CE-test - Ing. Gert Gremmen - ce-marking and more..." <[email protected]> >To: "Ken Javor" <[email protected]>, "Cortland Richmond" <[email protected]>, "ieee pstc list" <[email protected]> >Subject: RE: Site Correlation >Date: Sun, Jan 14, 2001, 1:10 PM > > > Hi Ken, > > Again you should definitely study EN 61000-4-6. > It assumes cable to have an impedance level (CM) of 150 Ohms, a > good average for many situations. It uses a coupling/decoupling network > matched to 150 ohms that feeds RF interference from or to the cable in > common mode. > Many CDN's exist therefore adapted to the cable type. The CDN approach > makes > high reproducibility possible, as it is not very difficult to maintain a > stable > 150 Ohm real impedance up till say 100 MHz. For complex cable types > a current clamp is used in a special version. Using low generator voltages > high level immunity test are allowed, due to the resistive coupling. > The basic CDN consist of only 3 components 1 R, 1 C and 1 L. > > Due to the well defined CM impedances and because cables leaving the EUT are > lead > over a ground plane at 30 mm height, the wire part up till the CDN is not > much losing it's power (characteristic impedance) over the 30 cm allowed to > the CDN. > > > > > Regards, > > Gert Gremmen, (Ing) > > ce-test, qualified testing > > =============================================== > Web presence http://www.cetest.nl > CE-shop http://www.cetest.nl/ce_shop.htm > /-/ Compliance testing is our core business /-/ > =============================================== > > >>>-----Original Message----- >>>From: [email protected] [mailto:[email protected]]On Behalf >>>Of Ken Javor >>>Sent: Sunday, January 14, 2001 12:45 AM >>>To: Cortland Richmond; ieee pstc list >>>Subject: Re: Site Correlation >>> >>> >>> >>>I think you misunderstood a couple of my arguments. A CE limit on cables >>>would not pre-empt the RE test, it would simply remove the cables as >>>radiation sources, thereby eliminating the need to arrange them >>>for maximum >>>radiation. A cable CE limit would be based on an ideal maximum radiation >>>orientation, therefore in practice measured radiation from a CE compliant >>>cable would always be below the RE limit. >>> >>>The size of the EUT would not play a role, since you would always perform >>>the RE test. >>> >>>And finally, I specifically talked about the absorber clamp >>>because it damps >>>out standing waves - the only issue, as Ing. Gremmen pointed out >>>earlier, is >>>how close can you get the clamp to the EUT - it must be within a small >>>fraction of a wavelength - say 0.1 lambda. >>> >>>Ken Javor >>> >>>---------- >>>>From: Cortland Richmond <[email protected]> >>>>To: "Ken Javor" <[email protected]>, ieee pstc list >>><[email protected]> >>>>Subject: Re: Site Correlation >>>>Date: Sat, Jan 13, 2001, 5:34 PM >>>> >>> >>>> Ken, >>>> >>>> When you ask how members "feel," you open a Pandora's box! >>>> >>>> We must still meet some kind of installed bottom line; our >>>equipment must >>>> not generate fields above some limit. (We can argue what that should be >>>> some other time.) >>>> >>>> However, when _designing_ an EMC solution, we can estimate >>>field strength >>>> based on some arbitrary gain, current and impedance for cables. >>>By assuming >>>> all common-mode currents flow in the worst possible directions -- here's >>>> our cable arrangement -- we come up with a conservative solution. >>>> >>>> But cables coming from a (say) two-meter square EUT cannot take all >>>> possible configurations. GR-1089 assumes a limited cable arrangement >>>> representative of a Central Office installation. And when an >>>EUT gets large >>>> enough, it's no longer enough to know what current flows in the cables >>>> anyway, because the EUT may be a principal radiator by itself. >>>> >>>> So I'd not want all radiated tests replaced. We sill need a >>>size limit to >>>> tell when we must use antennas, and when current probes. We also need a >>>> more flexible definition how and where cable current is to be >>>measured. Not >>>> al cables can be run along the floor on a reasonable test site. >>>If we must >>>> reach a current maximum with a probe, we may have to get five >>>meters from >>>> the EUT. That might require a ten meter diameter ground plane -- which >>>> brings to mind the saying: Be careful what you ask for; you >>>might get it! >>>> >>>> Regards, >>>> >>>> Cortland >>>> >>>> (Whose posting here reflect none of his employer's opinions) >>>> >>>> >>>> >>>> ====================== Original Message Follows ==================== >>>> >>>> >> Date: 13-Jan-01 00:50:16 MsgID: 1077-20414 ToID: 72146,373 >>>> From: "Ken Javor" >INTERNET:[email protected] >>>> Subj: Re: Site Correlation >>>> Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1 >>>> >>>> Date: Sat, 13 Jan 2001 02:43:51 -0600 >>>> Subject: Re: Site Correlation >>>> From: "Ken Javor" <[email protected]> >>>> Reply-To: "Ken Javor" <[email protected]> >>>> >>>> >>>> I must say that this thread has been a refreshing alternative to the >>>> EMC-law/regulations questions that typically occupy this service. Not >>>> complaining either, because If I suddenly found myself working >>>commercial >>>> EMC issues I would likely be flooding this line with those self-same >>>> questions. >>>> >>>> Almost as an aside, Mr. Heald raises an issue of enduring interest to >>>> myself >>>> and others. >>>> >>>> "Another important factor... is to manipulate the cables during testing >>>> (oh, >>>> how much easier our job would be without cables)." >>>> >>>> The same issue was raised parenthetically in my answer to the question >>>> about >>>> GTEM polarization. The issue is control of cable-sourced radiated >>>> emissions. I am now about to allegorically take a baseball bat to a >>>> hornets' nest... >>>> >>>> Bela Szentkuti pointed out almost twenty years ago that it would be much >>>> more efficient and accurate to analytically/experimentally determine the >>>> relationship between cable common mode currents and the >>>resultant radiated >>>> field based on the maximum possible radiation efficiency of >>>that cable, and >>>> use that relationship to derive a common mode current limit for >>>cables from >>>> 30 MHz to 1 GHz, using the absorbing clamp as a measuring tool. >>> This would >>>> speed up OATS or any other kind of RE testing by deleting the >>>requirement >>>> to >>>> maximize cable radiation. >>>> >>>> So this question is a poll. How do the subscribers to this service feel >>>> about cable common mode current control in lieu of direct measurement of >>>> cable-sourced RE measurement? The idea being that first you >>>would measure >>>> and bring cable cm CE into compliance with a cable-type limit >>>and only then >>>> would you make the RE measurement. The cables would only be support >>>> equipment which did not contribute to the RE profile, hence any measured >>>> emissions at or near the limit would be guaranteed EUT >>>enclosure-related. >>>> >>>> Polite responses only, please!!! >>>> >>>> Ken Javor >>>> >>>> >>>> >>>> ---------- >>>>>From: David Heald <[email protected]> >>>>>To: "Tudor, Allen" <[email protected]> >>>>>Cc: "EMC-PCST (E-mail)" <[email protected]> >>>>>Subject: Re: Site Correlation >>>>>Date: Fri, Jan 12, 2001, 9:36 AM >>>>> >>>> >>>>> >>>>> Greetings again. >>>>> I received some questions about this off list and there has >>>been more >>>>> discussion in this direction, so I thought I would throw my other two >>>>> cents in. >>>>> For small fully anechoic chambers with little room for >>>antenna height >>>>> adjustment, you should be able to have uncertainty of about 6dB or so >>>>> (10dB is much safer realistically) when you apply correction >>>factors for >>>>> a 10m site. The reason for this is, as John Barnes pointed out, the >>>>> absence of reflected waves being received in addition to the direct >>>>> waves. The key importance to a fully lined chamber (including the >>>>> floor) is that destructive waves are not present. With a reflective >>>>> floor, destructive waves can lower your readings by more than >>>30dB. Add >>>>> this to the 6 dB or so of uncertainty for additive waves and your total >>>>> error could be enormous. With an absorber lined floor, the >>>influence of >>>>> the destructive waves is eliminated or reduced, so a correlation of 6dB >>>>> (again 10dB is safer) should be achievable (this simply >>>accounts for the >>>>> absence of constructive interference). >>>>> Another important factor to ensure you don't have any surprises when >>>>> moving from precompliance to a compliance run is to manipulate the >>>>> cables during testing (oh, how much easier our job would be without >>>>> cables). Large signal strength changes can be achieved just by moving >>>>> cables a few inches. >>>>> I also have to agree with Gert's and Ken's comments on far field >>>>> measurements. I mentioned this in my original message, but didn't >>>>> elaborate at all. These are very important considerations that can >>>>> greatly affect any expected correlation to a 10m OATS. >>>>> >>>>> -- >>>>> David Heald >>>>> Senior EMC Engineer/ >>>>> Product Safety Engineer >>>>> >>>>> Curtis-Straus LLC NRTL >>>>> Laboratory for NEBS, EMC, Safety, and Telecom >>>>> Voice:978.486.8880x254 Fax:978.486.8828 >>>>> www.curtis-straus.com >>>>> >>>>> >>>>> Tudor, Allen wrote: >>>>> >>>>>> Greetings: >>>>>> >>>>>> What's the best way to correlate a pre-compliance chamber >>>(smaller than >>>> a 3m >>>>>> chamber) to a 10m anechoic chamber? Should I use a signal >>>generator and >>>>>> antenna or should I use a comb generator? >>>>>> >>>>>> Would the answer be different if I were correlating the pre-compliance >>>>>> chamber to an OATS? >>>>>> >>>>>> Thanks in advance. >>>>>> >>>>>> >>>>>> Allen Tudor, Compliance Engineer >>>>>> ADC DSL Systems Inc. >>>>>> 6531 Meridien Dr. >>>>>> Raleigh, NC 27616 >>>>>> phone: 919.875.3382 >>>>>> email: [email protected] >>>>>> >>>>>> >>>>>> ------------------------------------------- >>>>>> This message is from the IEEE EMC Society Product Safety >>>>>> Technical Committee emc-pstc discussion list. >>>>>> >>>>>> To cancel your subscription, send mail to: >>>>>> [email protected] >>>>>> with the single line: >>>>>> unsubscribe emc-pstc >>>>>> >>>>>> For help, send mail to the list administrators: >>>>>> Jim Bacher: [email protected] >>>>>> Michael Garretson: [email protected] >>>>>> >>>>>> For policy questions, send mail to: >>>>>> Richard Nute: [email protected] >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>>> ------------------------------------------- >>>>> This message is from the IEEE EMC Society Product Safety >>>>> Technical Committee emc-pstc discussion list. >>>>> >>>>> To cancel your subscription, send mail to: >>>>> [email protected] >>>>> with the single line: >>>>> unsubscribe emc-pstc >>>>> >>>>> For help, send mail to the list administrators: >>>>> Jim Bacher: [email protected] >>>>> Michael Garretson: [email protected] >>>>> >>>>> For policy questions, send mail to: >>>>> Richard Nute: [email protected] >>>>> >>>>> >>>> >>>> ------------------------------------------- >>>> This message is from the IEEE EMC Society Product Safety >>>> Technical Committee emc-pstc discussion list. >>>> >>>> To cancel your subscription, send mail to: >>>> [email protected] >>>> with the single line: >>>> unsubscribe emc-pstc >>>> >>>> For help, send mail to the list administrators: >>>> Jim Bacher: [email protected] >>>> Michael Garretson: [email protected] >>>> >>>> For policy questions, send mail to: >>>> Richard Nute: [email protected] >>>> >>>> ====================== End of Original Message ===================== >>>> >>> >>>------------------------------------------- >>>This message is from the IEEE EMC Society Product Safety >>>Technical Committee emc-pstc discussion list. >>> >>>To cancel your subscription, send mail to: >>> [email protected] >>>with the single line: >>> unsubscribe emc-pstc >>> >>>For help, send mail to the list administrators: >>> Jim Bacher: [email protected] >>> Michael Garretson: [email protected] >>> >>>For policy questions, send mail to: >>> Richard Nute: [email protected] >>> >>> > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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