Tuesday, Jul 22, 2008 at 18:52
Standard non halogen globes yes but halogen globes can have a mix of different gases to intensify the temp that the filament burns at, in these globes if the temp is not correct due to a lower or higher voltage being applied the filament will burn either to cold or to hot shortening the globes life.
+30, 50 and 80 globes have different combination of gas mixtures to generate more heat in the filament making it burn brighter, this is why +30, 50 and 80 globes use the same amount of current as a standard globe and the are not rated in watts but a percentage over standard globes whereby 55/60watts being standard (55/60+30, 55/60+50 and 55/60+80 ratings).
There is a limitation to how much heat versus output can be generated, if they made a 100watt +80 you will find it may generate to much heat for the globe design as the filament is already very thin.
If they made 100 watt globes bigger in dimension so the could use a thicker filament wire then you would not have a problem with reliability.
Much like H4 IPF Fat Boy globes, the glass section is much larger then other H4 globes so they can run a thicker filament wire for the higher temp they run at.
wikipedia says this
Principle of operation
The function of the halogen is to set up a reversible chemical reaction with the tungsten evaporating from the filament. In ordinary incandescent lamps, this tungsten is mostly deposited on the bulb. The halogen cycle keeps the bulb clean and the light output remains almost constant throughout life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some time it will reach higher temperature regions, where it dissociates, releasing tungsten and freeing the halogen to repeat the process. In order for the reaction to operate, the overall bulb temperature must be higher than in conventional incandescent lamps. The bulb must be made of fused silica (quartz) or a high melting point glass (such as aluminosilicate). Quartz being very strong, the gas pressure can be higher, which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so efficacy) for the same average life. The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail.
Regeneration of the filament is also possible with fluorine, but its chemical activity is so great that other parts of the lamp are attacked. .[1][1] [2]
The first commercial lamps used elemental iodine, were called Quartz Iodine Lamps,and were launched by GE in 1959. [3] [4] Quite soon bromine was found to have advantages, but was not used in elemental form. Certain hydrocarbon bromine compounds gave good results. [5] [6]. The first lamps used only tungsten for filament supports, but in some designs it has been possible to use molybdenum - an example being the molybdenum shield in the H4 twin filament headlight for the European Asymmetric Passing Beam.
High temperature filaments emit some energy in the UV region. Small amounts of other elements can be mixed into the quartz, so that the doped quartz (or selective optical coating) blocks harmful UV radiation. Hard glass blocks UV and has been used extensively for the bulbs of car headlights. [7] Alternatively, the halogen lamp can be mounted inside an outer bulb, similar to an ordinary incandescent lamp, which also reduces the risks from the high bulb temperature. Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.
For a fixed wattage and life, the efficacy of all incandescent lamps is greatest at a particular design voltage. Halogen lamps made for 12 to 24 Volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture). The range of MR16 (50 mm diameter) reflector lamps of 20W to 50W were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. More recently, wider beam versions are available designed for direct use on supply voltages of 120 or 230V.
Effect of Voltage on Performance
Tungsten halogen lamps behave in a similar manner to other incandescent lamps when run on a different voltage. However the light output is reported as proportional to voltage to the power of 3, and the efficacy proportional to the power of 1.3 [8] The normal relationship regarding life is that it is proportional to voltage to the -14. For example, a bulb operated at 5% higher than its design voltage would produce about 15% more light, and the efficacy would be about 6.5% higher, but would be expected to have only half the rated life.
Halogen lamps are manufactured with enough halogen to match the rate of tungsten evaporation at their design voltage. Increasing the applied voltage increases the rate of evaporation, so at some point there may be insufficient halogen and the lamp goes black. Over-voltage operation is not generally recommended. With a reduced voltage the evaporation is lower and there may be too much halogen, which can lead to abnormal failure. At much lower voltages, the bulb temperature may be too low to support the halogen cycle, but by this time the evaporation rate is too low for the bulb to blacken significantly. There are many situations where halogen lamps are dimmed successfully. However, lamp life may not be extended as much as predicted. The life span on dimming depends on lamp construction, the halogen additive used and whether dimming is normally expected for this type.
FollowupID:
582861