IAEEL newsletter 1/96
1000-watt sulfur lamp now ready
The 1-kW version of the electrodeless microwave sulfur lamp is now available in both the European and US markets, and the number of sulfur lamp installations is growing. In May 1996, a dimmable compact version of the lamp had been developed for the (European) 230-V market.
In IAEEL Newsletters 3/94 we reported on the first prototype 3.4-kW sulfur lamp made by the US manufacturer Fusion Lighting (See: "Sun on Earth"). The prototype lamp was installed in a few remote source lighting installations, in both the US (with light pipes) and in Sweden (with a reflector-based distribution system) (See:A Systems Approach to Remote Light Sources, IAEEL 4/94). The first prototype had a rather poor system efficacy, ~85 lumen/watt, and the extremely high-output bulb required cooling with compressed air, which made the lamp very noisy.
During 1995, Fusion continued to develop the 1-kW version. The system's total power consumption is 1375 W, and the bulb no longer requires cooling. Total lumen output is rated at ~130000 lumen. However, the lamp's efficacy has been rising constantly, and the lumen output has increased according to some measurements. The system efficacy of the lamp is presently claimed to be ~100 lm/W.
Fusion's present version (May 1996) of the "Solar 1000" lamp consists of two "boxes". One box houses the power supply unit and weighs about 22 kg (48lbs). The bulb and reflector are mounted on the second box, which houses the magnetron and weighs only a few kg. The bulb is very compact and constantly rotates to keep the plasma stable. Presently, the company only has a narrow-beam reflector with a rotationally symmetrical light distribution optimized for hollow light guides. Fusion only sells the lamp to original equipment manufacturers (OEM), and there is no price information available.
For the European market, Fusion has been cooperating with the Swedish defense electronics firm Celsius Tech, which specializes in magnetron technology for radar and radio communications equipment. During the winter of 1995/96, Celsius Tech developed a small switch-mode power-supply unit that totally replaces the 22-kg power-supply unit and can be installed within the same case that houses the magnetron. This new electronic power supply only adds marginally to the weight, so the whole lamp unit only weighs a few kilograms. The new power supply is claimed to be more reliable than the old unit. Moreover, with the new power supply the lamp is fully dimmable from 0 to 100% of maximum light output.
The new electronic power supply can also be integrated into a computerized monitoring and control system. This is especially valuable given that the life of the magnetron is much shorter than that of the bulb (presently 15 000-20 000 hours versus at least 50 000 hours for the bulb). The monitoring system can now keep track of each individual magnetron in a system and inform the maintenance crew when one needs to be changed.
Whereas Fusion only sells their lamps to original equipment manufacturers, Celsius Tech is willing to deliver lamp units to anyone who wants to buy them. The dimmable version will not be available until August 1996, but the present version is sold for SEK 15 600 (~US$ 2 500) in Europe.
The largest sulfur-lamp installation now exists in Sweden, where a large hollow-light-guide installation with 26 1-kW units has been set up in the post office's letter-sorting station in the city of Sundsvall in northern Sweden. The lamp is also being tested in a parking garage. Other projects planned in Sweden include an upgrade of the Lund Hospital installation (see IAEEL Newsletter 4/94) where the two 3.4-kW lamps will be replaced by four 1-kW lamps. For this project, other reflectors are being developed.
In the US, the Department of Energy is planning to install hollow light guides in a large post office sorting center in Denver, Colorado. Another light-pipe installation is planned in a large air hangar in Washington DC.
In Finland, a large installation is planned in a shopping center near the capital Helsinki, to be inaugurated in September 1996. Here some 20 sulfur lamps will be used to light up an atrium with a mirror-based distribution system. The 1-kW lamp has even been used in the private house of the Finnish industrialist Jaakko Pöyry, who uses it for lighting a combined entrance area and a living room. A UK installation with the lamp will also be completed by June in the entrance area of a new office complex in Sheffield. In Denmark, the large utility NESA is going to use the lamp in a show-case installation. What could develop into the most prestigious sulfur lamp project so far, however, involves the main arena for the Sydney Olympics 2000 where the winning proposal included the use of sulfur lamps.
Thus far, the most unorthodox project including sulfur lamps has been the temporary land art installation in Vienna, Austria, in October 1995 (by the artist, landscape architect Monika Gora and lighting designer Lars Bylund): Three sulfur lamps were used to light up a 25x10x8-meter white balloon from within. The balloon, which was anchored to the ground and was described as trying to capture some of the summer's fading sunlight, was named "A Volume of Light" (see photo below).