The characteristics of photosensors and electronic dimming ballasts in daylight responsive dimming systems

Daylight responsive dimming systems are being used to improve both the quantity and quality of the visual environment, and can significantly reduce the electric lighting requirement. Adequate accuracy and reliability of daylight responsive dimming systems are the major market barriers to their more widespread use. In an effort to overcome these barriers, this study involves the analysis of the spatial response of photosensors and their related mounting locations, and the performance consistency of electronic dimming ballasts. The characteristics of the spatial distribution of a series of photosensors were measured, and then the relationship between photosensor signals and the corresponding workplane illuminances was identified through field measurements. The relationship between the control voltage of electronic dimming ballasts and its corresponding light output ratio was also identified. The best-fit functions for this relationship when applying electronic dimming ballasts were derived such that a desired light output level can be obtained with proper control voltage of the electronic dimming ballasts.