High-Frequency Operating Characteristics of Metal Halide Lamps

High-frequency operating characteristcs of small-wattage metal halide lamps are investigated. Included are the spectral energy, the color temperature, the acoustic resonance, and the luminous efficency. Two electronic ballasts are built to drive the lamps with the sinusoidal current and the square-wave current, respectively. The experiments are conducted on tested lamps of 70 W and 150 W in a frequency range from 20 kHz to 300 kHz. Comparisons on the operating characteristics between two electronic ballasts and the effects of operating frequency are discussed from the experimental results.