Page 187 - Advanced Course

KNX ADVANCED COURSE

Figure 23: same as above, but at more external light – worst case situation !

Figure 24: again same configuration, but at complete darkness – rows 2 and 3 “waste”
energy!

What is the conclusion of the notes mentioned above?
If the offset of the slave is positive, then it will always be able to reach 100%, but cannot
dim down to 0%, it will turn off with the master. If it is negative, it can switch off, but not
reach 100% of dimming level.
So there is never a 100% positive solution as with individual light sensors per each row of
luminaries. However, using the configuration with the master at the window, and the
slaves with positive offsets in the inner parts of the room, will provide a good compromise.
The only slight disadvantage is, that the master will either have to turn off late (at more
than 500 lx, which avoids the “gap”, but causes a much higher level at darkness, or there
will be a situation, when the master turns off at 500 lx, where rows 2 and 3 still would need
some light, but will switch of with the master.

Home and Building Management Systems KNX Association
Lighting Control Lighting Control_E0310a.doc 28/34