Theben KNX Series Handbook page 54

4.6.10 Additional stage cooling
Control is done via a proportional controller.
Designation
Type of actuating value
Difference between main stage
and additional stage
Proportional band
PWM period
Transmission of actuating value
Send cyclically
RAMSES 718 P / RAMSES 718 S
The application programmes RAMSES 718 P/S
Values
Percent
PWM
0 K, 0.5 K, 1 K
1.5 K, 2 K, 2.5 K
3 K, 3.5 K, 4 K
1 K, 1.5 K, 2 K, 2.5 K
3 K, 3.5 K, 4 K, 4.5 K
5 K, 5.5 K, 6 K, 6.5 K
7 K, 7.5 K, 8 K, 8.5 K
3-30 min
Std.: 5 min
At change by 1%
At change by 2%
At change by 3%
At change by 5%
At change by 7%
At change by 10%
At change by 15%
do not send cyclically
every 2 min.
every 3 min.
...
every 45 min.
every 60 min.
Description
Control is done via a proportional
controller.
Continuous actuating value 0-
100 %
Pulse-width modulated switching
actuating value.
Defines the negative distance
between the current set point
and the set point of the
additional stage.
Example with base set point of
21 °C and difference of 1 K:
The main stage controls with the
base set point and the addition
stage controls with
base set point value – 1K = 20°C
With continuous additional stage,
Professional setting for adapting
control response to the room.
Large values cause finer changes
to the control variables with the
same control deviation and more
precise control than smaller
values.
An actuation cycle consists of a
switching-on and a switching-off
process
and forms a PWM period.
Example:
Actuating value = 20 %,
PWM time = 10 min: In an
actuating cycle of 10 min, 2 min
switched on and 8 min switched
off
(i.e. 20 % on/80 % off).
After what percentage change in
the actuating value is the new
value to be transmitted.
Small values increase control
accuracy but also the bus load.
How often should it be resent?
54