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LighTimes: DOE Releases CALiPER Report about Dimming Performance of LED-based PAR38 Lamps.

24 Apr 2014
G&H OL IS-1800H 18-Inch Integrating Sphere

April 22, 2014…The US. Department of Energy has released its CALiPER report covering the dimming of PAR38 LED lamps. The report notes that not all LED lamps are designed to be dimmable, and the LED lamps that are designed to be dimmable can exhibit different characteristics. The DOE points out that components such as controls and devices and other LEDs on the same circuit can effect dimming performance of a given LED lamp.

The driver, which interprets the signal from a control device is often the source of differences in performance, especially in integral lamps controlled by phase-cut dimmers. Such systems often have compatibility issues, where phase-cut dimmer traits interfere with the intended operation of the LED sources, or the LED source’s performance characteristics interfere with the intended operation of the phase-cut dimmer.
According to the DOE, another issue is that “dimmable” has no standard definition and claims of dimmability cannot guarantee any minimum level of performance. In addition to the differences in the maximum and minimum light output in the dimming range, the rate of dimming may change during dimming. Performance attributes such as LED package efficacy, driver efficiency, complete product efficacy, chromaticity, flicker, and power quality may also change during dimming.
The DOE notes that some phase-cut dimmers change the behavior of some LED lamps, and vice versa.These compatibility problems can result in undesirable behaviors such as changes in dimming rate, dead travel (little or no change in light output despite changes in dimmer setting), pop-on or dropout (sudden change in output not corresponding to the limit of the dimmer signal), flashes or ghosting, audible noise, reduced lifetime or reliability of the dimmer, and reduced lifetime or reliability of the LED product. These challenges result in highly unpredictable LED dimming performance.