Answers

Per IEC61373, long life test requires inputs of ASD .452 and .25, [is this g2/Hz? Yes] trans. and long., respectively, in the range of 5-20Hz, and at 3.9 and 2.9 RMS [how arrived at these numbers? Published in the test standard.] acceleration for trans and long, respectively. The test lab or supplier has opted to test in both x and y at 3.9 m/s/s, rather than use the lower 2.9m/s/s. Since this is a long life test as opposed to a resonance sweep, I'd guess the higher acceleration level is better (more stringent). However, is there a down side to testing at a more severe acceleration for this long life test? [Nothing obvious. How much stroke does this require of your shaker? I don't have the particualrs on the shaker, but, from further review of the report, I believe this was a time saving concession with the supplier having confidence that the unit would pass regardless.] The UUT is an inverter package with lots of power conversion components mounted within the enclosure. [Where is it located in service? Are your numbers based upon in-service measurements? The enclosure is mounted undercar, upside down - this hadn't occurred to me, the test oriented the enclosure in the right side up orientation which does not even closely represent the in-service condition. Yes, the test criteria and levels are based on numbers derived from in-service measurements.] Also, the resonance is defined as a doubling of the input vs output displacement amplitude, or a doubling of the g-level amplitude? [What has this to do with the earlier sentences? Practically nothing, different subject. My question should have been, is there any way to determine resonant frequencies using raw data of freq vs log g accelerations? In reviewing these reports in the past, I'm accusotmed to seeing plots of displacement in the vertical vs freq on the horiz, with a doubling of the reference amplitude at some measuring point on the UUT being defined as resonance. However, the test house did not provide this output format.]