The U.S. Department of Energy's CALiPER program has released Report 20.2, which is part of a series of investigations on LED PAR38 lamps. Report 20.2 focuses on dimming, flicker, and power quality characteristics evaluated with a single dimmer.

The dimming, flicker, and power quality behavior of the LED PAR38 lamps evaluated in this study was less consistent than that of conventional halogen PAR38s. Among the trends that emerged from the performance of the 33 LED lamps that were listed as dimmable:

•Most LED products produced more relative light output at a given dimmer level than the benchmark halogen PAR38s.

•When operated by a switch, almost all of the LED PAR38s exhibited less flicker than a magnetically ballasted fluorescent lamp, and more than two-thirds exhibited flicker less than or comparable to that of a halogen lamp. However, when dimmed, about half of the lamps exhibited more flicker than a magnetically ballasted fluorescent lamp, and almost all of the LED products exhibited more flicker than a typical halogen lamp.

•While all of the LED lamps tested met the current ANSI-defined thresholds for power factor when operated by the switch, nearly one-third had a power factor less than 0.5 at some point over the dimming range, which would not meet the standard.

For a closer look at the findings, download the full report.