![]() Therefore, halogen lamps have been developed which can be directly used with the grid voltage. That increases the cost, requires additional space and may introduce significant losses of electrical power. However, one then requires an additional transformer or an electronic device for getting the required low supply voltage from a grid voltage of 230 V or 110 V. That also has the advantage of avoiding any electric shocks current-carrying wires may be touched by human beings without the risk. Halogen Lamps for Low and High Voltages Figure 1: A halogen lamp for operation with 230 V grid voltage.Īs explained above, the highest energy efficiency is achieved with lamps made for low operation voltages such as 12 V. The relatively low cost of production is then a more important factor. Therefore, halogen lamps are also gradually phased out, although tentatively later than ordinary incandescent lamps.ĭespite the moderate energy efficiency, such lamps can be a good choice for applications where only few operating hours per year are required. Note that other light sources such as fluorescent lamps and light emitting diodes (LEDs) are still far more efficient than halogen lamps. Halogen lamps with the same power but a lower operating voltage of 12 V can range substantially higher luminous efficacies around 20 lm/W, but the difference gets somewhat smaller when considering power losses in the required lamp power supply. Typical 230-V household halogen lamps with a power consumption of 60 W, for example, reach a luminous efficacy around 16 lm/W. Consequences of the increased filament temperature are (a) an increased luminous efficacy, leading to improved energy efficiency, and (b) an increased color temperature, which ironically gives it a “colder” appearance, which is closer to daylight. ![]() The advantage resulting from the explained halogen cycle is that such a lamp can be operated with a substantially higher filament temperature (around 2900 to 3200 K) while still maintaining a reasonable lifetime and avoiding metal deposition on the glass, which would lead to darkening. Energy Efficiency of Halogen Lamps Halogen lamps are significantly more efficient than ordinary incandescent lamps, but still far less efficient than some other light sources. Halogen lamps must not be confused with metal-halide lamps, which are based on an entirely different operation principle. Therefore, one typically uses relatively small bulbs (with the glass being closer to the hot filament), which are often made of quartz glass ( fused silica) because that material can withstand substantially higher temperatures than ordinary bulb glass.Īs the filament is typically made of tungsten, as for most other incandescent lamps, the term tungsten halogen lamp is frequently used. In order to avoid deposition of metal on the glass bulb, the bulb needs to become relatively hot during operation temperatures around 250 ☌ are appropriate. When it gets close to the hot filament again, it dissociates, and the released metal is deposited on the filament. The halogen chemically reacts with evaporated tungsten metal from the filament, forming a halide which moves around in the bulb. That gas filling can establish the so-called halogen cycle. Halogen lamps are a special type of incandescent lamps, where the bulb is filled with a gas mixture which contains a small amount of a halogen such as iodine or bromine.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |