ABB i-bus KNX Product Manual page 171

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ABB i-bus KNX
Planning and application
Explanations of terms
These variables are only partly available in the Software-Tool for commissioning, see Software-Tool online
help.
Sensor value
Actual value
Control parameter (setpoint)
This value corresponds with the physically measured value on the sensor input, which
results from the room brightness detected by the Light Sensor LF/U 2.1 (luminance of the
area monitored by the sensor). This value is displayed exclusively as an additional
auxiliary value during commissioning using an external commissioning tool (Software-
Tool). The sensor value does not comply with the lighting intensity (Lux value) in the room,
but rather it is an electrical variable that is present on the sensor input of the DLR/A. The
sensor value is used to directly detect brightness values in the detection range of the light
sensor.
The actual value of the control circuit is the fed back of the control path. If the controlling
lighting group is only assigned to a light sensor, the actual value corresponds to the sensor
value.
If several light sensors are allocated to a lighting group, the actual value is determined
from the sensor values of the individual sensors.
In Parameter window - Gx Light
the largest or the average sensor values are used for light control calculations.
For further information see: Constant lighting
The control parameter corresponds to the setting of the control if the setpoint brightness
value is set in the room. For this reason, the control parameters can be set equal to the
control setpoint. In the following, we refer to the setpoint.
The setpoint is the decisive control value in practical application for constant lighting
control. The DALI Light Controller calculates the setpoint for the lighting so that the actual
value to be set is as near as possible to the predefined setpoint (control parameter) with all
room lighting conditions.
Due to the differing ambient conditions in rooms (incidence of light, reflections and
absorption conditions), this setpoint cannot be easily achieved via the figure value defined
in the ETS, but must rather be set using a daylight and artificial light calibration. With this
calibration, the lighting characteristic and the technical lighting properties of the room are
automatically detected by the DALI Light Controller in order to match the control parameter
to the room.
For further information see: Constant lighting
Irrespective of this calibration, overshoot or undershoot of the setpoint lighting value can
occur during phases in ongoing operation of constant lighting control. These are even
greater with greater differences of the reflection and absorption conditions from the original
ambient conditions during the calibration procedure. A further reason for the deviation is a
direct or indirect incidence of light on the light sensor. As a result, a deviation of +/- 10 %
from the setpoint is normal.
controller, page 95 you can parameterize if the smallest,
control, page 167
control, page 167
DLR/A 4.8.1.1 | 2CDC507128D0202 169