A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Photoelectric control of equi-illumination lighting systems
AbstractThe ability of a photoelectrically controlled lighting system to maintain a constant light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to electric light levels and by the geometry and location of the photosensor. We describe the major components of a typical equi-illumination system, discuss the design and operation of such a system, and examine the effects of the control algorithm and photosensor shielding. Equations for the control photosensor signal are developed that separate the signal into electric light and daylight components. We then present mathematical descriptions for the constant set-point control algorithm used by most manufacturers. An alternative, sliding set-point algorithm is proposed in which the total photosensor signal is a linear function of the signal's daylight component. Computer simulations of the performance of dimmable lighting control systems driven by ceiling-mounted photosensors were run for a test room under various daylight conditions. Control systems using the constant set-point algorithm were unable to provide the target light level continuously, although shielding the ceiling-mounted photosensor from the window luminance resulted in higher maintained levels with less variability than did using unshielded photosensors. The use of a sliding set-point algorithm in lieu of a constant set-point algorithm improved the performance of systems driven by both shielded and unshielded photosensors. When a sliding set-point system was used in conjunction with a photosensor shielded from the window, a nearly constant light level was maintained at the task surface regardless of daylight condition.
Photoelectric control of equi-illumination lighting systems
AbstractThe ability of a photoelectrically controlled lighting system to maintain a constant light level on a task surface by responding to changing daylight levels is affected by the control algorithm used to relate the photosensor signal to electric light levels and by the geometry and location of the photosensor. We describe the major components of a typical equi-illumination system, discuss the design and operation of such a system, and examine the effects of the control algorithm and photosensor shielding. Equations for the control photosensor signal are developed that separate the signal into electric light and daylight components. We then present mathematical descriptions for the constant set-point control algorithm used by most manufacturers. An alternative, sliding set-point algorithm is proposed in which the total photosensor signal is a linear function of the signal's daylight component. Computer simulations of the performance of dimmable lighting control systems driven by ceiling-mounted photosensors were run for a test room under various daylight conditions. Control systems using the constant set-point algorithm were unable to provide the target light level continuously, although shielding the ceiling-mounted photosensor from the window luminance resulted in higher maintained levels with less variability than did using unshielded photosensors. The use of a sliding set-point algorithm in lieu of a constant set-point algorithm improved the performance of systems driven by both shielded and unshielded photosensors. When a sliding set-point system was used in conjunction with a photosensor shielded from the window, a nearly constant light level was maintained at the task surface regardless of daylight condition.
Photoelectric control of equi-illumination lighting systems
Rubinstein, Francis (author)
Energy and Buildings ; 6 ; 141-150
1984-01-01
10 pages
Article (Journal)
Electronic Resource
English
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