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Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGSstandards | PROGRESS REVIEWof the testing regime. LM-80 does not predictlumen maintenance beyond the testingperiod. In the process of creating LM-80, furtherdiscussion around the extrapolationmodel was necessary, but it was importantto get the testing method out so that testingcould begun immediately across a widerange of devices. The more data we have,the more likely it is that we can develop agood prediction model. Another committee,TM-21, is in the process of developing sucha model now.LM-80 measures lumen maintenanceof LED light sources including LED packages,arrays and modules only. It does notinclude luminaires. LM-80 specifies a numberof electrical and thermal measurementssuch as voltage and current (AC or DC levels),voltage waveshape, etc.The case temperature is obtained from a testmeasurement point designated by the manufacturer.A key aspect of LM-80 is the value ofthe temperature measurement levels. Theyinclude 55°C, 85°C and a third temperatureselected by the manufacturer. During testingthe airflow in the region must be minimized,and any specifications for operatingorientation and spacing can be provided bythe manufacturer.LM-80 currently requires 6000 hours oftesting time, which is a long time. Some haveargued that this is too long, but unless a betterway comes along to predict lumen maintenancefrom a relatively short testing timethen there is no means with strong confidencethat provides an accurate measure oflumen maintenance. It is very likely, withouta lot of supporting data, that any predictionmethod will be limited to some multiplier ofthe testing period. The testing interval for thephotometric measurements is a minimum ofLINKSComing in part 2The next part of this article will coverfurther details on LM-80 as well aslooking at the various Guidelines (e.g.Title 24, Energy Star) that call on theStandards described above. The articlewill also look at the impressive array ofstandards that are currently in process,and the need for harmonization on aglobal basis. ◀1000 hours, so that sufficient data points canbe collected for a good sequence from whichtrends can be calculated.Webcast on photometry and standards: www.ledsmagazine.com/features/6/2/15More information and images: www.ledsmagazine.com/features/6/4/1_____________LEDsmagazine.com APRIL 2009 31Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next PageABE FMaGS