High Pressure Metal Halide Lamp



       Metal halide lamps are similar to standard high pressure mercury lamps buy metal halides in the form of thallium, gallium and scandium, are added to the mercury. The inclusion of these halides improves efficacy and colour rendering properties when compared with the standard high pressure mercury lamps (Figure 1).

       One form of starting circuit (Figure 2) consists of a switching devices (ignitor) and ballast to produce the high starting voltage. When the supply is switched on, the mercury discharge produces a very high temperature and the metal halide additives serve to suppress the mercury spectrum. The result is a crisp white light.

High pressure metal halide lamp circuit data
. Lamp efficacy 80 – 108 lumens per watt
. good colour rendering.better than MBF lamps
. low power consumption and running costs
. lamp takes time to reach its full brilliance
. after switching off it will not restart until the pressure inside the lamp has fallen
. average lamp life 15000 hours
. application – suitable for any indoor or outdoor commercial and industrial uses where good quality lighting is required, for example, stores, exhibitions, sports stadia and TV lighting
. metal halide lamps should be used in enclosed luminaires
. lamp designation – MBI
. the additional fluorescent phosphor to the inside surface of the glass bulb (MBIF lamps) helps to improve the colour rendering properties of the lamp.

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