Brightness Detection Function; Function Of The Constant Lighting Control - ABB i-bus KNX Product Manual

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ABB i-bus KNX
Planning and application
4.9.6

Brightness detection function

The Light Sensor LF/U 2.1 of the DALI Light Controller DLR/S 8.16.1M detects the luminance of the
surfaces in its detection area and converts it to a current. Before the light reaches the photodiode, it
passes through a light filter, whose maximum pass band attributes are in the visible wavelength range of
the human eye. The luminance is, on the one hand, dependent on the lighting intensity, i.e. the intensity of
the daylight or artificial light, and on the other hand on the characteristics of the surfaces (reflections)
which are to be illuminated. If, for example, the surface in the detection range of the light sensor is
completely covered with white paper, the light sensor measures a different luminance at the same lighting
intensity as when the surface is covered with gray recycled paper. When setting the setpoint, the
luminance is measured by the light sensor and stored as a setpoint value. Subsequently, the light
controller will control the artificial light level in the room so that it more and more accurately achieves this
setpoint value, i.e. the light controller attempts to keep the luminance and not the lighting intensity at a
constant level.
4.9.7

Function of the constant lighting control

The task of constant light control is to control the setpoint brightness which results at a reference point in
the room as accurately as possible. Starting from the actual brightness, the setpoint brightness is
approached in steps (brightness change over time).
A control step is defined by the increment (brightness change) and the step time (time duration), in which
the brightness change is performed.
A simplified lighting control can in principle look as follows. The setpoint brightness is achieved starting
from an actual brightness level in three steps:
DLR/S 8.16.1M | 2CDC 507 100 D0202 183