Physical constraints on the performance of LED lamp replacements for A-19, PAR-38 and MR-16 configurations

摘要

Since the introduction of LED technology into the general illumination lighting market, one desired feature has been the ability to replace the luminaire lamp in a similar manner to conventional sources (e.g. screw or plug in). Due to thermal management issues, successfully implementing this feature has proven difficult with many manufacturers simply integrating the LED sources into the luminaire. However, there are LED replacement lamp products on the market that manufacturers claim to be the equivalent of their conventional source counterparts. This paper will examine the relationships between lifetime, light output, source efficacy, thermal management and physical size for three common lamps: the MR-16, the A-19 (standard incandescent shape) and the PAR-38 (standard floodlight shape). The author will evaluate the physical size envelope for the three lamp types. Next, a theoretical model for maximum thermal dissipation to ambient will be determined. Then using data from LED manufacturers, junction temperature limits versus lifetime will be evaluated and used to determine maximum input power. This input power limit combined with manufacturer's data and assumed optical and electrical losses will be used to evaluate potential light output of the lamp and compared to conventional lamp outputs. Upper limits for light output will be determined.