Very-Low Voltage Halogen Lamps
Tungsten halogen incandescent lamps operating at very low voltage by means of a voltage transformer.
Performance: Being incandescent lamps, they have a much lower efficacy than any other families of lamps (e.g. fluorescent lamps, high intensity discharge lamps). However, thanks to the halogens, their efficacy can typically be up to 20% higher than standard tungsten lamps, and their luminous properties are more constant over time. Moreover, newest halogen lamps are also available with infra-red coating that is said to increase their luminous efficacy by 25-30% compared to conventional halogen lamps.
Compared to compact fluorescent lamps, their efficacy is much lower but on the other hand their performance is independent of temperature and orientation. They also project light efficiently over long distance, and they present no power quality or compatibility concerns. In addition, they provide optimal colour rendering.
In addition, their small, strong bulb with robust internal construction allows luminaires and optics to be miniaturised and made less expensive.
Applications: Accent lighting and display lighting has traditionnaly been achieved using tungsten spotlights. A wide range of tungsten-halogen lamps is now available and these can be used effectively for this purpose, especially where tight control of beam spread is necessary. Other good applications include high-ceiling downlighting and “instant-on” power floodlighting. They should be used sparingly in rooms with low ceilings. They are expensive and the concentrated filament is too dazzling to expose to the direct view of occupants.
Prior to using tungsten halogen lamps, the use of compact fluorescent lamps (better efficacy) should be investigated.
Because very-low voltage halogen lamps require a voltage transformer to operate, their use as direct substitution of standard tungsten lamps is not possible.
Lifetime: 5-150 Watt
12 – 22 lm/W (typical: 18 lm/W)
2000 – 4000 hours