Lighting A to Z

Halogen OperationReflectorHalogen CapsuleCut-away view ofa PAR38 HalogenHalogen Bulbs are technically incandescent bulbs, butthey have three features that make them superior tostandard incandescent.They are Brighter, Whiter, and Last Longer.A Halogen lamp has a thin filament. A thin filament producesmore light than a thick one. This makes it brighter and whiter.But how does it last longer with a thin filament? The answer is…The Halogen CycleThe filament is in a glass capsule. The glass capsule containsan incandescent bulb, but before the tungsten deposits onthe bulb wall, the halogen gas transports it back to thefilament—replenishing it and keeping the bulb clean and bright.The halogen gas actually regenerates the filament. This is whyHalogen bulbs last much longer and stay bright throughout theirlife. However, the tungsten does not go back exactly to the samespot on the filament, so eventually it gets weak at one point andfails, ending the cycle.VoltageHalogen lamps are available for low-voltage operation (for whicha transformer is needed) or for 120 volt as direct replacementsfor incandescent lamps.Lighting A–Z 5