Performance Characteristics of Fluorescent Lamp and Ballast Combinations

Evaluation of different lamp types in a luminaire using a given ballast will show variations in efficiency, due to thermal, and other, factors. Investigations have shown that if modified photometric procedures are performed using an absolute basis rather than a rated lumen basis, great differences in candlewpoer values may be obtained which correspond to field experience. Certain ballast/lamp combinations, while very efficient in terras of the ratio of luminaire lumens to bare lamp lumens, develop a lumen delivery considerably lower than the lamp-rated lumens.This paper will report upon measurements of lamp and ballast combinations and indicate the seriousness of the problem. “Luminaire Factor” is defined, which allows lighting design calcualtions to be corrected for the difference between Absolute and Rated-Lamp Lumens. A further problem considered in the paper is a correction of photometric test reports due to air movement and temperature. An “Application Factor” is proposed which allows compensation fo...