Thanks. The test is being done at a remote lab, so I can't witness it. In spite of that, I think their setup is OK.
What I don't understand is why this test standard would specify such tight measurement variation. The measured values are far below the limit, and if I calculate their standard deviation*3, it's still far below the limit. In my original example, the 13mA signal could vary no more than 13mA * 5% = 650uA before it would be considered a failure. In fact, it might be easier to meet the 5% repeatability test if my emissions were higher. A measured value of 285mA (just under the limit) would allow 285mA*5%=14mA of variation without exceeding the spec. To contrast, the EN 61000-3-3 voltage fluctuation/flicker standard has a procedure involving manually-switched equipment. This procedure requires 24 test measurements, with the high and low values discarded. The CISPR 22 emissions standard also has a detailed statistical procedure (the 80%/80% rule?) to determine whether emissions should be considered 'out of spec'. Pat Lawler pat dot lawler at verizon dot net On Mon, 19 Apr 2004 19:42:53 -0700, "Kurt Fischer" <[email protected]> wrote: >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 > >-----Original Message----- >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
