Which brings up a point just to add for accredited labs that do this in-house. I agree that it is a characterization and not a calibration,
My understanding is that if you do this in house you may have make sure that you meet the Accreditation Body Traceability requirements as an in-house calibration, which would include uncertainty calculations for the characterization measurement and all other applicable requirements. Have witnessed some interesting discussions on this. Best regards, Mac Elliott [ ] Motorola Confidential Restricted (MCR), [ X ] Motorola Internal Use Only [ ] General Public From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Spencer, David H Sent: Tuesday, January 27, 2009 1:46 PM To: Price, Edward; emc-p...@ieee.org Subject: RE: Calibration Standards for LISN Ed, I've seen white board presentations at the IEEE Symposia, that suggest that the AC mains impedance does impact the final conducted emissions reading. A quick glance at Lab 34 (or CISPR 16-4-2) show that in terms of uncertainty the LISN impedance variations can account for as-much-as 3.6dB. All that being said, I didn't write the standard. I don't see any variation in my facility when I connect or disconnect the LISNs. BUT, as many lab are accredited these days and it is part of a standard that many use, it's worth at least taking a look at if for no other reason than quantifying the uncertainty rather than using the generic figures (which I'm sure no one does). Regards, Dave Spencer EMC Engineer Xerox Corp. From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Price, Edward Sent: Tuesday, January 27, 2009 1:25 PM To: emc-p...@ieee.org Subject: RE: Calibration Standards for LISN So I would have to deduce then that ANSI C63.4 is schizophrenic, in that it doesn't trust the specified LISNs to work as they say they should. If the standard wants you to measure the LISN plus your facility filter, then you are characterizing your facility, not just the LISN. Logically, where does it end? Surely the impedance of the local powerlines has a slight effect on the overall impedance, and then what about the generators at the power station? Of course, I'm being absurd here, but why can't they just spec a LISN that provides sufficient isolation under all conditions? Ed Price ed.pr...@cubic.com WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty > -----Original Message----- > From: Spencer, David H [mailto:david.spen...@xerox.com] > Sent: Tuesday, January 27, 2009 10:15 AM > To: Price, Edward; emc-p...@ieee.org > Subject: RE: Calibration Standards for LISN > > Ed, > > I agree, and I've verified that with the LISN(s) I use there is no > impact; however, ANSI C63.4, E1, b) states that unless it can be > shown that the RF filters do not impact the impedance then you must > perform the verification with the RF filters in circuit. > > Really it's a case for either performing the verification in house OR > sending the RF filters with the LISN out as part of the calibration > (at least once). > > I know some facility RF line filters are not easily removed! > > Regards, > > Dave Spencer > EMC Engineer > Xerox Corp. > > -----Original Message----- > From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Price, > Edward > Sent: Tuesday, January 27, 2009 1:04 PM > To: emc-p...@ieee.org > Subject: RE: Calibration Standards for LISN > > > > But isn't it the purpose of the AMN to present an impedance to the EUT > which is unaffected by whatever unknown impedance exists at the source > of the power? - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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