Terminology In Lighting Technology; A.4.1 Lighting Intensity - ABB i-bus KNX Product Manual

®
ABB i-bus KNX
A.4 Terminology in
lighting technology

A.4.1 Lighting intensity

© 2008 ABB STOTZ-KONTAKT GmbH
Appendix
If the Light Controller LR/S x.16.1 (X = 1 or 2) is used for the constant
lighting control, the Light Sensor LF/U 2.1 measures the light density of
the illuminated area in its detection range, e.g. or the floor or the desk.
However, with the Luxmeter used for setting the constant lighting control,
we measure the lighting intensity, i.e. the light flux which shines on the
measurement sensor of the Luxmeter.
These different measurement methods can – but must not necessarily – lead
to the state where the constant lighting control does not correctly function in
practice.
This is not an ABB-specific phenomena bit rather is the case for all constant
lighting controls which function according to this principle.
Different lighting technology terms are explained in the following to improve
understanding of what is involved.
A lighting intensity measurement device referred to as a: Luxmeter,
measures the lighting intensity E in lx (Lux), i.e., the intensity which
is used to illuminate a surface in the unit lx (Lux).
The lighting intensity E is defined as follows:
φ
E = / A
E = lighting intensity in lx (Lux)
φ
= luminous flux in lm (Lumens)
A = illuminated surface area m
The lighting intensity detects the luminous flux which originates for a
luminaire and which shines on a defined surface. In order to measure
the lighting intensity the Luxmeter must point in the direction of the light
source, i.e. to the light or the sun.
Some examples for lighting intensities:
Cloudless summers day up to
Overcast winters day
Office lighting
Dark winters day
Full moon night
The Luxmeter for measurement of the lighting intensity is comparable to a
directly measuring photometer used by professional photographers, which is
pointed directly at the sun in order to determine the correct film exposure
settings.
The lighting intensity does not actually say anything about the apparent
brightness on the eye as the brightness of the observed surface is not
detected with the lighting intensity.
2
100 000 lx
20 000 lx
500 lx
400 lx
0.3 lx
144