I read in !emc-pstc that ITL-EMC User Group <itl-...@itl.co.il> wrote (in <2D1037012914D4118DB8204C4F4F5020275AD1@ITLLTD01>) about 'Use of Voltage Probe' on Sun, 25 May 2003:
>According to Section 4.1.3 Voltage probes of ANSI C63.4, "A voltage probe >may be used for radio-noise voltage measurements when measurements are made >at a user's installation (see 5.6) or when the ac current level exceeds the >current-carrying capability of commercially available LISNs. For such >measurements, the method shown on Figure 4 may be used. Special precautions >shall be taken to establish a reference ground for the measurements." This is an example of useless wording in a standard. What 'special precautions' did the authors have in mind? To achieve or avoid what? They don't tell us, and coyness is definitely not a virtue in such a case. All it does is create confusion, as we see here. >Accord to Section 5.6 Testing at manufacturer's location or user's >installation, "The voltage probe (see 4.1.3) shall be used for ac powerline >conducted emission measurements. (See IEEE Std 13-1988 for additional >information.) Neither a reference groundplane nor an LISN shall be installed >for user's installation testing unless one or both are to be a permanent >part of the installation." >The above sections seem to me to contradict one another regarding the >reference groundplane. No, because you have no 'grounds' (ouch!) for assuming that the 'special precautions' imply 'use a ground plane'. >Can we interpret the above (Section 4.1.3 "Special precautions shall be >taken to establish a reference ground for the measurements.") to be >applicable only when testing in the laboratory and the ac current level >exceeds the current-carrying capability of commercially available LISNs? >Please comment. No, it is reasonable and technically correct to pay attention to where you ground the voltmeter connected to the probe, wherever the measurements are carried out. It would be logical to connect it to the enclosure of the EUT, if it is metal, with the shortest practicable lead. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
