Technical Note: Dimming LED Integral Lamps Prepared by: Rachel Taranta, Lighting Research Center Date: March 2, 2011 Introduction: Incandescent A‐lamp and PAR lamp replacement with LED integral lamps is recently a topic of widespread interest. During the past year, several integral LED lamps, intended to replace incandescent lamps, have entered the marketplace. One of the requirements for these lamps is compatibility with dimmers designed for incandescent lamps. This has raised several questions:  Are the existing dimmers used with incandescent A‐lamps suitable for dimming LED integral lamps?  Is the dimming performance of LED integral lamps acceptable on existing residential dimmers to end‐users?  Do all commercially available household dimmers dim different lamp technologies in a similar manner?  Are there any negative effects caused by using LED integral lamps with these dimmers? Objective: To survey triac‐based dimmers and understand their dimming characteristics with incandescent A‐
lamps, dimmable LED integral lamps and dimmable CFLs. Methodology: Seven commercial LED lamps (6–12 W range) and various replacement lamp types (incandescent PAR, incandescent A‐lamp, etc.), procured from retailers during the latter part of 2010, were tested with several dimmers in the laboratory to understand their dimming behavior. All lamps tested clearly stated on packaging that product is dimmable. Results: NEMA LSD‐49 (2010) identifies several key parameters in comparing performance of lamp/dimmer combinations. Some of these parameters include:  Minimum light output*  Maximum light output**  Change in dimmer setting for which there is no change in output  Pop on/drop out† Each of these parameters can be depicted by graphing light output as a function of light level control. Figure 1. Relative light output as a function of light level control for seven different dimmable LED integral lamps, an incandescent, and a dimmable CFL on the same triac dimmer. http://www.lrc.rpi.edu/assist The results in Figure 1 show that:  The tested CFL had the highest minimum light output at 28% of non‐dimmed output.  The lamps exhibited a range of maximum dimming behaviors, all above 90% light output when undimmed.  In the range from 82% to 100% light level control, Lamp 7’s output exceeded the undimmed output.  All lamps exhibited some change in light output throughout light level control.  Lamps 4, 6 and 7 popped on at 18%, 22%, and 4%, respectively. Figure 2. Relative light output as a function of light level control for seven different LED integral lamps, an incandescent lamp, and a CFL on the same triac dimmer. As seen in Figure 2, several lamps performed markedly different with this dimmer:  Lamp 6 had its minimum output at 66% of light output when undimmed.  Lamps 1, 2, and 3 showed a reduction in maximum light output with this dimmer, with their maximum light output now at 87%, 90% and 85%, respectively.  Lamp 3’s light output did not change from 0% to 80% of dimmer actuation, and more than 90% of its dynamic range took place within the last 5% of the dimmer’s travel.  There were no dimmer settings for which any of the lamps did not emit light. In summary, a lamp’s performance with one dimmer does not predict its performance with another. Any of the four parameters discussed are subject to variation based on different lamp/dimmer combinations. *“Minimum” light output is the lowest quantity of light the lamp emits when dimmed, as a percentage of light output when the lamp is connected to line voltage (i.e., with no dimmer). ** “Maximum” light output is the quantity of light the lamp emits on the highest dimmer setting, as a percentage of the light output when the lamp is connected to line voltage (i.e., with no dimmer). † When a lamp emits no light below a certain dimmer setting, and “pops on” suddenly while ramping up, or when a lamp suddenly turns off when ramping down, this is called “pop on” or “drop out.” Note: All data shown is for “ramp up”; that is, lamps are started with dimmer off and ramped up to their maximum light output, except the CFL, which exhibited no change in light output during ramp up. For the CFL, the dimming profile shown is for “ramp down.” Reference: NEMA LSD 49‐2010. 2010. Solid State Lighting for Incandescent Replacement – Best Practices for Dimming. Rosslyn, VA: National Electrical Manufacturers Association Contributors: N. Narendran, Terence Klein, Martin Overington, and Jennifer Taylor, Lighting Research Center About ASSIST: ASSIST was established in 2002 by the Lighting Research Center at Rensselaer Polytechnic Institute as a collaboration between researchers, manufacturers, and government organizations. ASSIST’s mission is to facilitate broad adoption of solid‐state lighting by helping to reduce major technical and market barriers. ASSIST members include: Acuity Brands Lighting; Amerlux Global Lighting Solutions; Bridgelux; China Solid State Lighting Alliance; Cree; Everlight Electronics Co., Ltd.; Federal Aviation Administration; GE Lighting Solutions; ITRI, Industrial Technology Research Institute; Intematix Corp.; LG Electronics; LG Innotek; Lighting Science Group; Lite‐On; NeoPac Lighting; New York State Energy Research and Development Authority (NYSERDA); OSRAM SYLVANIA/OSRAM Opto Semiconductors; Permlight; Philips Lighting; Sharp Laboratories of America; Seoul Semiconductor; United States Environmental Protection Agency; WAC Lighting. http://www.lrc.rpi.edu/assist 2