Friday, November 24, 2006

Induction Technology: A New Generation of Light

This is one of the first articles I ran into that went into details with Induction Lighting Systems.

The original post can be found here

The main attraction of induction lighting is incredibly long lifetime. In a fluorescent lamp, the electrodes at either end are the weakest link, and the lamp usually fails when the cathode coating on one of the electrodes is depleted after 15,000–20,000 hours. Induction lamps have no such electrodes, so their rated lifetimes are as long as 100,000 (that's over 11 years, running 24/7!). They also have good vibration resistance and low starting temperatures, making them a good choice for rugged operating environments.

Induction lamps are discharge lamps, where the idea is to get mercury or other atoms to elevate their energy level, then discharge a photon as they fall back to normal. Induction lamps differ from fluorescents—their closest relative in the lighting family—in the way they energize the mercury atoms. Instead of striking an arc between electrodes in a tube, an electromagnetic field is generated by a carefully shaped coil. The field created by the coil induces a current flow in the gas/mercury blend within the lamp. This current excites the mercury atoms and starts the flow of photons. Mercury atoms emit UV photons; phosphors lining the lamp wall absorb the UV photons and in turn emit visible photons.

Like high-quality fluorescents, induction lamps offer instant strike, instant restrike, color stability, 80+ CRI, high power factor and low THD. A ballast—in this case called a field generator—is required to provide the power electronics that drive the induced current in the lamp. Finally, induction lamps have a coupling device that wraps the induction coils around some part of the lamp itself. Induction technology is not dimmable at this time, but it could be in the future.


The first lighting product to use induction technology was the Philips QL lamp, originally introduced in Europe in 1990 and in the U.S. in 1992. The QL is a globe-shaped lamp available in three sizes at 55W, 85W and 165W, and two color temperatures at 3000K and 4000K. With the coupling device at its base, it looks a bit like an overgrown A-lamp. The separate 2.65MHz field generator is rated for operation at or below 75 degree Celsius; its lifetime is cut in half for each 10-degree Celsius rise above that temperature. Lumen maintenance is 70 percent at 60,000 hours and 55 percent at 100,000 hours. Philips product specialist, Austin Cahill, says that the QL is primarily an OEM product and that the market is growing, particularly for outdoor installations such as tunnel and freeway sign illumination.

GE Lighting's Genura lamp was the next on the scene, although its emergence in the U.S. market was fitful. This 23W lamp is a self-contained induction lamp with a standard Edison screwbase. With its relatively low light output (1100 lumens) and 15,000-hour lifetime, the Genura is really more akin to a screw-in compact fluorescent. The Genura is available in color temperatures of 2700K and 3000K and is not dimmable. Gary Crawford of GE Lighting says that although the lamp is available in some retail stores, it is mostly a commercial product sold through distributors. Applications include downlights in hotel lobbies and hallways and retail fixtures where they can sometimes replace halogen PAR lamps. Crawford says that the Genura actually handles hot environments better than compact fluorescent alternatives.

Although it is now a forgotten chapter in history, in 1992, a media campaign blanketed the country, touting the "lamp of the future"—the so-called E-lamp from Intersource Technologies. The E-lamp was an induction lamp that was first targeted at the downlight market. Unfortunately, the company seemed to have spent more of its funds on marketing than on engineering, and the product never made it to shelves.

The next induction lamp to reach the market was the Osram Sylvania Icetron, introduced in 1996. The Icetron lamp has two cylindrical field sources at opposite ends of a rectangular tube and is available in 100W and 150W models; a 75W version is due for release. Color temperatures are 3500K and 4100K, and lumen maintenance is 70 percent at 60,000 hours and about 64 percent at 100,000 hours. Like the QL, Icetron has a separate field generator; its rated maximum temperature is 70 degrees Celsius.

"The product's acceptance rate was slow at first, but now we're finding applications that go beyond our initial focus," said Dwight Kitchen, manager of commercial engineering at Osram Sylvania. One such application is the Jefferson Memorial in Washington, D.C. where Icetron is used to light the portico area of the structure. Added Kitchen, "This increased demand for Icetron has resulted in our decision to launch a 75W version later this quarter."

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