A New Optimized Fluorescent Lamp and Ballast for Low- Energy General Lighting Applications

A new fluorescent lamp and ballast system has been developed which minimizes system input power while maintaining light output close to values provided by conventional lamps and ballasts. The 28-WT-12 lamp designed for the new system utilizes a redesigned electrode structure which allows the lamp to be started in the rapid start manner but operated in an instant start mode to maximize the discharge efficacy (lumens/watt) while reducing lamp cathode power requirements. A matching two-lamp ballast incorporates a solid-state switching device to turn off the cathode heating circuit automatically once the lamps have started. Both lamps and ballasts are physically interchangeable with conventional equipment so that existing luminaires can be converted without luminaire, lampholder, and wiring modifications. This new lamp/ballast system can achieve efficacy values exceeding 80 Im/W-more than 25 percent better than the performance of conventional fluorescent systems of the early 1970's-along with the excellent life and reliability characteristics typical of electromagnetically ballasted systems. Economic analyses indicate that the new system is appropriate for many new commercial general lighting installations, although it is particularly suitable as a retrofit system for installations where power reductions are essential but where conversion costs must be minimized and illumination levels preserved.