CHAPTER 09 : EXPANDING KNOWLEDGE OF LED TECHNOLOGY
Figure 9.5: Examples of excellent thermal management
Other features of LEDs Lighting professionals are able to select the perfect lamp and beam angle for any application. LED lamps are now available in a range of beam angles from 10â ° to 120â ° with a full range of intermediate beam angles. Similarly, a range of colours is available to suit any particular application or architectural requirement. The range of lamps and luminaires which are now available from manufacturers will meet the stringent requirements of lighting professionals and their clients. Perception that LEDs are inherently directional Manufacturers of earlier LEDs made use of epoxy optical lenses in order to focus the available light forward. High quality LED lamps now make use of hardened optical glass lenses to provide accurate beam angles. Other top quality LED products make full use of the fact that a LED can emit light in any direction which enables the manufacture to use sophisticated reflector technology in order to achieve specific light distribution appropriate for the particular product type such as for flood lights and street lights.
LED Life Expectancy There is no standard industry life expectancy for a LED. The lamp life definition for traditional light sources is the time at which 50% of the test sample has burned out. Quality LEDs generally do not fail by burning out but will slowly reduce in light output over time. As solid state devices they will continue to operate even after 100 000hrs continuing to use electrical power even if they produce little useful light. In a comparison of lumen maintenance near the end of the rated life for traditional light sources shows that with the exception of metal halide lamps, they still have 90% of their initial light output by the time that they have operated after 10 000hrs. In recent time, quality LEDs maintain their light output at 90% of their initial light output at 20 000hrs. This is an indication of the constant improvement and advancement in LED technology. In a number of instances this improvement is directly attributable to the advancements made in thermal management.
THE SUSTAINABLE ENERGY RESOURCE HANDBOOK, VOLUME 2
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