Technical information

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Light planning
Technical information
1. C-plane angles: 0° ≤ C
X
< 360°
2. γ -angles: 0° ≤ γ < 180°
Symmetrical light distribution
A 28 W fluorescent lamp (2600 lm)
gives, directly beneath it, approxi-
mately 375 cd/klm.
Asymmetrical light distribution
At a maximum luminous intensity
angle of 25° a 28 W fluorescent lamp
gives approximately 580 cd/klm.
Light measurement
The luminaire’s light distribution is measured on several C-planes
around the luminaire, at intervals of at least 15°. First measure-
ment plane (C=0°) is across the lamps’ longitudinal axis. γ-angles –
several angles are measured, at least every 5 degrees (see figure).
Light distribution curve
The light distribution curve drawn in a polar diagram denotes the
luminaire’s luminous intensity in dierent directions as a function
of viewing angle in one or more planes. It is usually represented by
an unbroken line that indicates the light distribution perpendicular
to the light source’s longitudinal axis and with a dashed line that
indicates the light distribution in direction of the longitudinal axis.
The values of the light distribution curves are scaled to correspond
to 1000 lm from the light source (cd/1000 lm, cd/ klm). This is why
it is often possible to show luminaires with dierent outputs on a
common polar diagram.
Isolux diagram
The diagram shows, using curves (or scales) a predened area, in-
side which the horizontal illuminance exceeds the curve’s lux value.
The position of the luminaire is usually indicated on the diagram.
Alternatively, the isolux diagram can be represented by a 3D dia-
gram, which is best suited for showing the uniformity of the light-
ing installation. The calculation points’ illuminance values can be
introduced onto the premises’ layout drawing and the results given
in table form. The results are available in all the above mentioned
forms in DIALux.
≥ 700 lx
650–700 lx
600–650 lx
550–600 lx
500–550 lx
≤ 500 lx
wall zone
12 m
10 m
Light distribution curve
Isolux diagram
Light measurement
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