Hi John,
A mains frequency magnetic loop is numerically “well described” mathematically. All you should really need to do is take accurate physical measurements of the geometry and use a calibrated current meter to measure the input. The magnetometer is a nice check, but shouldn’t be necessary. I’ve used the argument with both NVLAP and NIST and they have agreed (at least one each auditor, YMMV). Respectfully, Brent G DeWitt Westborough, MA From: Flavin, John [mailto:john.fla...@teradata.com] Sent: Thursday, April 01, 2010 3:24 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Verifying magnetic field strength for 61000-4-8 Prior to running a 61000-4-8 magnetic power frequency test, we place a magnitometer at the center of the coil (no EUT), and adjust the voltage/current into the primary of the step down transformer until the field strength is correct. We then record the voltage and current levels, and use these for the test. We do this measurement for each of the 3 coil orientations (We have large floorstanding EUTs, so it's easier to reorient the coil rather than the EUT). The only problem we are encountering is that we have been unable to find any cal lab that will give us a traceable calibration for the magnitometer, (which I doubt our assessor will like). Our cal lab does not do this type of calibration, and of the several they contacted about sub-contracting this, more than one said that "they didn't want to go there". So, my questions 1) How are other people verifying the field strength, so that it's traceable? 2) Are there cal labs that can provide traceable calibrations for magnetometers? John D. Flavin Teradata TCP Engineering 17095 Via del Campo San Diego, CA 92127 john.fla...@teradata.com V: (858) 485-3874 F: (213) 337-5432 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
