E-lamp

Schematic of the Genura induction lamp. The power supply converts ordinary 60 or 50 hertz current into high-efficiency power that is fed into an electrical coil. The coil excites a gas plasma inside the bulb, releasing UV radiation that strikes the bulb's phosphor coating and is converted into visible light.

"Whatever Happened to the E-Lamp?"

In an effort to build a better light bulb, three manufacturers are producing or developing electrode-less induction lamps. But, so far, these lamps have not made it into the residential market.

by

Barbara A. Atkinson

1994

November/December

Home Energy Magazine Online

In April 1994, General Electric (G.E.) Lighting announced that "the world's first practical compact high-tech induction reflector lamp" would be on the market in Europe within weeks. The lamp was on display at the European Hannover Fair in April and at Light Fair in New York in early May. It will be sold in the United States by the fourth quarter of 1994, according to G.E. At first calling it an E-lamp,* G.E. now simply designates their new reflector lamp by its trade name of Genura.

Haven't we heard of this technology before? Home Energy's Sept/Oct '92 issue reported the announcement of major investment funding for Intersource Technologies' E-lamp, an electrode-less induction lamp. Because of its compact size and longer life, the E-lamp would aim to replace the compact fluorescent lamp (CFL) as the state-of-the-art efficient light bulb.

Going Commercial

The news for households is that market research has convinced Intersource that the high price (about as much as a CFL) is a major barrier for residential consumers, for now. The company believes acceptance of the technology in the commercial market will be required before a strong residential market will develop. Meanwhile, G.E.'s product is not approved for use in the U.S. residential sector at all. Philips' "QL" induction lamp is a high wattage light source used only in the commercial and industrial sectors.

Intersource has continued research on its E-lamp, aiming toward a 1,500 lumen, 20-some watt replacement for the 100-watt PAR reflector lamp. Its efficacy is estimated at 60 lumens per watt (measured with center beam lumens). The company is looking for a prospective industry partner to produce prototype products by the end of 1994. While the lamp is approved by the Federal Communications Commission (FCC) for use in the residential sector, Intersource has moved away from a screw-in lamp design. Instead they plan to package the lamp inside a luminaire through OEMs (original equipment manufacturers) for the commercial/industrial market. Intersource has no plans to design an A-line version in the near future.

In the meantime, other manufacturers' research efforts on induction lighting has started to bear fruit. Thorn Lighting in the United Kingdom had a development program for electrode-less induction lamps. U.S.-based G.E. Lighting acquired Thorn in 1991 and continued the induction lighting program. The birth of the Genura lamp culminated an international collaboration among engineers in the United States, England, and Hungary. The lamps are produced at G.E.'s Tungsram plant in Hungary.

The first Genura model, now on sale in Europe, is a 23-watt reflector lamp that replaces a 100-watt incandescent reflector lamp. Because of voltage differences, the version sold in the United States will be the equivalent of a 75-watt reflector lamp. It will reportedly retail for about $20.

G.E. rates the lumen output of the 23-watt lamp at 1,100 lumens, compared with 940 lumens from the 75-watt incandescent reflector it replaces and 1,500 lumens from an electronic CFL 23-watt reflector. Thus, it is slightly less than 50 lumens per watt (Lm/W), much better than the 12.5 Lm/W of the incandescent reflector but less efficacious than the CFL's 65 Lm/W. G.E. will introduce Genura lamps in other wattages in 1995.

G.E.'s Genura is more compact than CFL reflector lamps and is actually smaller than the incandescent reflector lamp it replaces. The E-Lamp will also have size advantages over the CFL reflector lamp.

Interference?

The Genura lamp operates at 2.6 megahertz (Mhz), because Europe has standardized at this frequency for induction lighting. The lamp needs shielding for conducted and radiated electromagnetic interference (EMI) emissions. The reflector portion of the lamp provides enough shielding to meet FCC EMI requirements for 2.6 Mhz. However, residential FCC requirements are stricter and the Genura does not meet them. The company is now attempting to convince the FCC to permit use of the lamp for residences.

Intersource's E-lamp operates at 13.56 Mhz. This is within the Industrial/Scientific/Medical (ISM) band in which the FCC allows unlimited radio-frequency emissions. However, to meet the FCC's residential requirements, the lamp must be shielded to keep emissions in the 40-68 Mhz range (3rd through 5th harmonics of the operating frequency).

Since there is no filament to burn out or electrodes to fail, an induction lamp can be turned on and off without affecting lamp life. Product life is limited only by the lamp phosphor depreciation. G.E. states that the Genura lamp will still have 70% of its rated lumen output at 10,000 hours, and 50% at 20,000 hours. Intersource rates its lamp lifetime as 20,000 hours with 70% of rated lumen output. The color rendering index of the Genura is good at 82.

Both the E-lamp and the Genura have problems starting up at low temperatures, and neither is recommended for outdoor use. Neither can be used on dimming circuits either, but both G.E. and Intersource plan to introduce dimmable induction lamps in the future.

Intersource states that the E-lamp will have "high power factor and low total harmonic distortion." The power quality of the Genura lamp is similar to that of lower-end CFLs, and not as good as high-power-quality CFLs. The second generation of the lamp may be power- quality-corrected.

Is the compact induction lamp the revolutionary lighting product originally acclaimed by the press? The best induction lamps on the horizon will be less efficacious than CFL reflectors. Until G.E. can obtain FCC permission to open a residential frequency band in which the Genura can operate, people will be able to enjoy its benefits only at work or in other public places. The E-lamp can be used in the residential sector, but will not be available as a screw-in retrofit.

Size is the first advantage of these lamps, allowing them to fit in more incandescent sockets. Also, the beam spread or directional quality of the light, critical to the utility of a reflector lamp, is better than that of a CFL reflector. While it's not a point source (such as a spot light or an MR16 reflector), as a flood lamp its beam quality is more like that of an incandescent than of a linear CFL. The induction lamp certainly competes favorably with the incandescent reflector lamp on a life-cycle cost basis, and in many applications it has the design edge over the CFL reflector.

* E-lamp is a registered trademark of Intersource Technologies.

[Barbara A. Atkinson is a principal research associate in Lawrence Berkeley Laboratory's Energy Analysis Program. She performs analysis on lighting policy and building energy efficiency for the United States, Canada, Europe, and Central America.]