LED industry test standards inadequate life difficult to predict

In many applications, compared with the traditional light source, the duration of most of the LED lighting system for longer. However, some solid-state lighting (SSL) users may find the faults of speed choice of LED products is much faster than the statement in the data table of life. Life cycles will hurt consumer confidence. LED system fault can be fatal (product cannot luminescence) or data differences (light, but much less than the design value).

The LED system has many components (Fig. 1), any component failure may lead to system failure. However, the current industry practice test LED device, and the lumen depreciation time (such as 70% parameter failure) as LED system service life. As the industry standard only requires testing of a component in the system, and only consider one type of failure assessment system of LED life, so manufacturers report product life may be more than the actual use of the consumers in some applications are much longer. American Rensselaer Lighting Research Center (LRC) conducted a study, explain the problem, and put forward the potential changes in practice.

A ^ 1:LED system component diagram

Since 2009, Rensselaer Polytechnic Institute Lighting Research Center (LRC) has been in the research of LED system on the development of life, a short-term prediction of life test program. The solid-state lighting system and Technology Alliance (ASSIST) earlier research found that funding, is the cause of the failure duration by delta temperature or on / off temperature change cycle and the residence time or system working in the maximum steady state temperature (see Figure 2). In 2014, Bonner's Electric Power Bureau and the New York state energy research and Development Administration (NYSERDA) jointly funded the expansion of an earlier study. In this study, three types of LED system from the market to buy the test, including LED A, LED MR16 lamp lamp and LED downlight, tested a total of 277 kinds of LED products.

Figure 2:LED - temperature - cycle curve

Solid state lighting SSL test development

Overall, the results of the study show that, in order to more accurately estimate the LED life of the system, testing the new practice must include the system test and the on / off switch. In the report system of life, should be two kinds of failure modes (fatal or parametric) in a short time as a product life, because in the application, the LED system may have two types of faults, and according to the conditions, a type of dominant.

The results of the study show that, if the working temperature and the typical on / off mode are known, we can develop a test program to accurately predict the life of any application in the LED system. Through the testing of the entire LED system, including the power cycle sufficient residence time, and by considering the fatal and parameter fault, can accurately predict the life of LED system in the testing period 3000 hours.

At present, product specifications set incorrectly is expected by the industry to the LED product life cycle data caused by the test requirements. Therefore, the urgent need to modify the industry test standards, guide product manufacturers and consumers to better. (compiled: LEDinside James)

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