There seems to be something wrong with this standard or the interpretation of it. The repeatability test should be to ensure that there is a high probability that the units are really under the limit. Say the limit is 300 mA. And say we test ten units and get 10,10,20,20,30,30,40,40,50, and 50 mA. The MEAN is 30 while the standard deviation is 15. Not much chance that these units are above the 300 mA spec. Dave Cuthbert
When the 'Repeatability' clause in EN61000-3-2:2000 (clause 6.3.2.1) is applied, is the comparison value (reference value) the result from another test run, or is it the test limit? For example, the harmonic test limit is 300mA, and the values from two test runs are 7.4mA and 13mA. 1) If the comparision value is from the other test run: 13mA-7.49mA -----------*100=42.4% (failing the test) 13mA 2) If the comparison value is the test limit: 13mA-7.49mA -----------*100=1.8% (passing the test) 300mA From: [email protected] [mailto:[email protected]] On Behalf Of Ralph McDiarmid Sent: Tuesday, April 20, 2004 11:16 AM To: [email protected] Subject: RE: measurement repeatability Why is there a repeatibility requirement for this standard, when there is not one for the other EMC standards? Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. From: Kurt Fischer [mailto:[email protected]] Sent: April 20, 2004 7:43 AM To: 'Hall, Ken'; 'Pat Lawler' Cc: [email protected] Subject: RE: EN61000-3-2 repeatability test Hello, I do not have a copy of the standard so I am relying on memory: 1. The 5% repeatability requirement stated in the standard refers to Instrumentation repeatability and validation (as Ken referred to in his email). 2. The problem stated in Pat's email is that the EUT has different measurement results when measured at different times. It seems that the solution path is to determine why the EUT generates different LF emissions profiles and determine if these profiles meet the limits in a reasonable number of cases or trials per the standard. To the best of my memory, there is no requirement that the repeatability measurements of the EUT itself be +/- 5%. Regards, Kurt Fischer From: Hall, Ken [mailto:[email protected]] Sent: Tuesday, April 20, 2004 5:53 AM To: Kurt Fischer; Pat Lawler; [email protected] Subject: RE: EN61000-3-2 repeatability test Hello, We just purchased the York HFG01for Site reproducibility/RoundRobin testing and use the HPET ( the for cyclic checks. The HP59510A switch box is replaced by a solid state relay the load resistors are glowcoils. Regards, Ken Hall _____ From: [email protected] on behalf of Kurt Fischer Sent: Mon 4/19/2004 7:42 PM To: 'Pat Lawler'; [email protected] Subject: RE: EN61000-3-2 repeatability test You should use the same EUT (which must be stable and repeatable). If you are obtaining drastically different results then you do not know if it is the EUT or the test setup/instrumentation that is effecting the results. I would suggest using something like an incandescent light bulb to run the test and check the repeatability of the instrumentation and test setup. Just my 2 cents. Good Luck, Kurt From: [email protected] [ mailto:[email protected]]On Behalf Of Pat Lawler Sent: Monday, April 19, 2004 5:36 PM To: [email protected] Subject: EN61000-3-2 repeatability test When the 'Repeatability' clause in EN61000-3-2:2000 (clause 6.3.2.1) is applied, is the comparison value (reference value) the result from another test run, or is it the test limit? For example, the harmonic test limit is 300mA, and the values from two test runs are 7.4mA and 13mA. 1) If the comparision value is from the other test run: 13mA-7.49mA -----------*100=42.4% (failing the test) 13mA 2) If the comparison value is the test limit: 13mA-7.49mA -----------*100=1.8% (passing the test) 300mA Method 1 seems overly stringent, but I can't find anything in the standard covering the method. Is this detail covered in another standard (like 61000-4-7?) --- Pat Lawler pat dot lawler at verizon dot net This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
