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Proceedings Paper

Projecting LED product life based on application
Author(s): Nadarajah Narendran; Yi-wei Liu; Xi Mou; Dinusha R. Thotagamuwa; Oshadhi V. Madihe Eshwarage
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Paper Abstract

LED products have started to displace traditional light sources in many lighting applications. One of the commonly claimed benefits for LED lighting products is their long useful lifetime in applications. Today there are many replacement lamp products using LEDs in the marketplace. Typically, lifetime claims of these replacement lamps are in the 25,000-hour range. According to current industry practice, the time for the LED light output to reach the 70% value is estimated according to IESNA LM-80 and TM-21 procedures and the resulting value is reported as the whole system life. LED products generally experience different thermal environments and switching (on-off cycling) patterns when used in applications. Current industry test methods often do not produce accurate lifetime estimates for LED systems because only one component of the system, namely the LED, is tested under a continuous-on burning condition without switching on and off, and because they estimate for only one failure type, lumen depreciation. The objective of the study presented in this manuscript was to develop a test method that could help predict LED system life in any application by testing the whole LED system, including on-off power cycling with sufficient dwell time, and considering both failure types, catastrophic and parametric. The study results showed for the LED A-lamps tested in this study, both failure types, catastrophic and parametric, exist. The on-off cycling encourages catastrophic failure, and maximum operating temperature influences the lumen depreciation rate and parametric failure time. It was also clear that LED system life is negatively affected by on-off switching, contrary to commonly held belief. In addition, the study results showed that most of the LED systems failed catastrophically much ahead of the LED light output reaching the 70% value. This emphasizes the fact that life testing of LED systems must consider catastrophic failure in addition to lumen depreciation, and the shorter of the two failure modes must be selected as the system life. The results of this study show a shorter time test procedure can be developed to accurately predict LED system life in any application by knowing the LED temperature and the switching cycle.

Paper Details

Date Published: 14 September 2016
PDF: 8 pages
Proc. SPIE 9954, Fifteenth International Conference on Solid State Lighting and LED-based Illumination Systems, 99540G (14 September 2016); doi: 10.1117/12.2240464
Show Author Affiliations
Nadarajah Narendran, Rensselaer Polytechnic Institute (United States)
Yi-wei Liu, Rensselaer Polytechnic Institute (United States)
Xi Mou, Rensselaer Polytechnic Institute (United States)
Dinusha R. Thotagamuwa, Rensselaer Polytechnic Institute (United States)
Oshadhi V. Madihe Eshwarage, Rensselaer Polytechnic Institute (United States)


Published in SPIE Proceedings Vol. 9954:
Fifteenth International Conference on Solid State Lighting and LED-based Illumination Systems
Matthew H. Kane; Nikolaus Dietz; Ian T. Ferguson, Editor(s)

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