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Abstract
A family of medium wattage ceramic discharge metal halide (CDM) lamps operating on magnetic ballasts was introduced several years ago to the North American market. These medium wattage (MW) lamps (175W – 400W) provide excellent color consistency, high color rendering properties, and long life. However, due to tungsten sputtering and evaporation, wall blackening and consequent lumen reduction is inevitable at late life. Moreover, the efficacy for these lamps is typically in the moderate range of 90 lumens per watt.
In this article we present the new technically advanced medium wattage ceramic discharge metal halide lamps that operate on new efficient electronic ballasts. The features and performance for these technically advanced MW ceramic lamps are compared with the three existing metal halide lamps; probe-start (also known as switch-start) quartz metal halide lamp, pulse-start quartz metal halide lamp, and the first generation ceramic metal halide lamp. By utilizing new chemical fillings and an optimized arc tube shape, the new MW ceramic metal halide lamps have high efficacy up to 123 lumens per watt, excellent lumen maintenance, and long service life. The typical color rendering index (CRI) is 90 and the saturated red color index (R9) is 40 or higher. Furthermore, the lamps are compact and suitable for universal operation, which are desirable for improving optical performance and overall fixture efficiency. The lamps are dimmable to 50 percent of the nominal power. With these new and improved features, the next generation of energy efficient MW CDM lamps is ideal for general lighting applications including outdoor, high bay industry, public spaces, and retail lighting.