This VDE application guide describes the procedure of limiting function for the prediction of reduction in luminous flux of LED packages which can later be used for the testing of LEDs. The procedure can be used in connection with the thermal acceleration method (Arrhenius model), if required.
Advantages of lighting with LED include their long service life compared with many other light sources. However, at present there is no international standard for measuring and predicting the service life and reduction in luminous flux of LEDs. Subject to certain conditions, this application guide provides an opportunity to predict the reduction in luminous flux. The procedure can thus replace the 6 000 h luminous flux test on the LED package of a module according to IEC/PAS 62717 or an LED lamp according to IEC/PAS 62612, going far beyond these tests in its statement by making Manufacturer declarations on the reduction in luminous flux of LEDs verifiable up to a range of approximately 50 000 h.
It should be emphasized that the procedure is unsuitable for higher integrated LED products such as LED lamps or LED modules. For these products the life expectancy of the other components used normally is the limiting factor, e. g. capacitors. The procedure neither covers the time behaviour of other parameters such as total failure, change in colour temperature and colour reproduction.
This VDE application guide is based on discussions in IEC/SC 34A which were not continued beyond the stage of committee draft in this international committee. Subcommittee DKE/UK 521.1 "Elektrische Lampen" of the DKE German Commission for Electrical, Electronic & Information Technologies of DIN and VDE (www.dke.de) has adopted this application guide for publication at its meeting in May 2012.