Understanding the reliability of LED luminaires

Abstract

The purpose of this paper is to educate both manufacturers and end users on what constitutes the overall reliability of an LED luminaire and the reliabilities of individual subsystems. Wide ranges of LED luminaires are available in the market to meet the needs of a specific applications, hence a potentially wide range of product performance characteristics exist. The different subsystems in an LED luminaire introduce other potential reliability issues that will be critical in deciding the overall system lifetime. The mutual dependency of subsystems and their interactions make the prospect of characterizing LED luminaire reliability challenging. Best design practices ensure that the overall luminaire reliability will be decided by a small number of subsystems, thus reducing the complexity. In this paper, a general theory of assessing the reliability of the optical, electrical and thermal subsystems of an LED luminaire is discussed. How the remaining useful lives of the subsystems are obtained from their degradation profile and how the remaining useful life of the entire system is derived from them are explained. The theory explained in this paper is useful in designing experiments to express the reliability of an LED luminaire and its subsystems in terms of remaining useful life.