1355 Induction Lighting

Electrodeless Induction Systems

Since the introduction of the first electric light, a search has been on for long-life lighting. The reason for this search is to reduce the cost associated with changing lighting components at or near their end of rated life—maintenance cost.

The lamps used in induction systems have no electrodes to wear out as other lamps, such as fluorescent and HID lamps do. The lamps can last much longer without electrodes. Long life is the primary advantage of these systems. These systems can provide a good payback where maintenance labor cost is high. When compared with other light sources, electrodeless induction systems will operate 5-8 times longer than fluorescent and metal halide systems and about 4 times longer than HPS systems. In addition, induction lamps come ON relatively quickly and have short re-strike time compared with HID lamps.

Instead of using electrodes to generate electrons as is done in fluorescent lamps, electrodeless systems produce light by means of induction—the use of an electromagnetic field to induce a plasma gas discharge into a tube or bulb that has a phosphor coating. No electrons are needed, since the gas discharge is induced into the bulb or tube by a high-frequency electronic generator that supplies the electromagnetic field. These systems provide white light with a minimum color shift and CRI

and lumen depreciation values are similar to fluorescent lamps.

Each of the two primary electrodeless system lamps has a unique size and shape and require new fixtures that are designed to optically match each unique shape. There is no common electronics package for these products since they operate on much different frequencies. The electronics package must be fairly close to the glass envelopes and the maximum mounting distance is restricted to the wire length supplied on the electronics package. These are independent systems and are designed so that both the glass envelopes and the electronics are changed out together at end of life.

Genura™ Lamp

GE Lighting developed an electrodeless induction lamp labeled Genura™ and introduced it in the US in 1995. Genura™ is a compact R30 reflector lamp with a standard medium base that is intended for use as a retrofit lamp (in place of a 100-watt A lamp, a 75-watt R30 lamp or a 65-watt R30 lamp) in recessed downlights (cans). This product is a lamp and not a system, so it is covered here before the induction systems.

QL Induction Lighting System (Figure 13.10)

Philips Lighting developed this induction system and introduced it to the European market in 1991. In 1992 the QL was introduced to the US market. The QL system is comprised of three components. 1) a high-frequency generator, 2) a power coupler and 3) the glass bulb. The high-frequency generator is in a separate electronics package that provides the 2.65 MHz current to the power coupler (antenna) through a coax cable. The power coupler sits inside the enclosed glass discharge bulb shaped like a large A lamp. The bulb, which contains an inert gas

Figure 13.10 QL Lighting System (Source: Philips Lighting)

and a small amount of mercury is attached to the power coupler by a plastic lamp cap that uses a click system. Like fluorescent lamps, the inside walls of the bulb are coated with a phosphor coating. When the high frequency electromagnetic field is applied to the bulb, the gas is ionized and the lamp produces photons at UV frequency and visible light in the same manner as a fluorescent tube. The photons collide with the phosphor coating and cause the lamp to glow. Full brightness is achieved in 10-15 seconds. The system meets FCC requirements as a low EMI design.

There are three models—55-w, 3,500 lumens, 85-w, 6,000 lumens, and 165-w, 12,000 lumens—with lumen efficacy of 64-73 LPW. The 55-watt model has a maximum overall diameter (MOD) of 85 mm (~3 3/8"), the 85-watt model has a MOD of 111 mm (~ 4 3/8"), and the 165-w model has a MOD of 131 mm (~5 5/32"). QL bulbs are available in two color temperatures—3000K (warm) and 4000K (cool).

The main advantage of the QL system is its long life—average rated life is 100,000 hours. Philips rates life as 20% failures at 60,000 hours. This long life advantage is especially important where maintenance cost is high. The current emphasis in the U.S. is in outdoor lighting systems—street, roadway, and tunnel lighting systems. Several fixture manufacturers have incorporated the QL in their designs.


The Inductively Coupled Electrodeless system— ICETRON™—was developed by Sylvania. This electrodeless system consists of three parts: 1) a unique rectangular 'donut' shaped bulb—filled with an inert gas and a small amount of mercury, 2) two ring-shaped ferrite core couplers—one at each of the short sides of the bulb, and 3) a separate high-frequency (200-300 KHz) generator. A plug-in connector attaches leads from the couplers to the electronic generator. The driver may be mounted up to 66 feet away from the lamp.

When the high frequency electromagnetic field is applied to the donut-shaped bulb between the ferrite cores at each end, the gas inside the bulb is ionized and produces light by inducing a circulating current in the bulb, which generates photons at UV frequency. These photons collide with the phosphor coating and cause the lamp to glow. ICETRON™ lamps strike and re-strike instantly.

There are three ICETRON™ lamps—70-w, 100-w, and 150-w—and two drivers. Table 13.16 shows the combinations of lamps and drivers and the resulting system performance.

The mercury in the glass envelope is in the form of an amalgam, providing a universal burn situation.

Table 13.16 ICETRON™ System Performance (Source: Sylvania)






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