West Control Solutions KS 92-1 - Manual (Page 23)

3.5.11 Examples for self-tuning attempts
(controller inverse, heating or heating/cooling)
Start: heating power switched on
Heating power Y is switched off (1).
When the change of process value X
was constant during one minute (2),
the power is switched on (3).
At the reversal point, the self-tuning at-
tempt is finished and the new parameter
are used for controlling to set-point W.
Start: heating power switched off
The controller waits 1,5 minutes (1).
Heating power Y is switched on (2).
At the reversal point, the self-tuning
attempt is finished and control to the
set-point is using the new parameters.
Self-tuning at the set-point a
The process is controlled to the
set-point. With the control deviation
constant during a defined time (1)
(i.e. constant separation of process value
and set-point), the controller outputs a
reduced correcting variable pulse (max.
20%) (2). After determination of the
control parameters using the process
characteristic (3), control is started
using the new parameters (4).
Three-point controller a
The parameter for heating and cooling are
determined in two attempts. The heating
power is switched on (1). Heating para-
meters
Pb1, ti1, td1 and t1 are de-
termined at the reversal point. Control to
the set-point occurs(2). With constant
control deviation, the controller provides a
cooling correcting variable pulse (3). Af-
ter determining its cooling parameters
Pb2, ti2, td2 and t2 (4) from the
process characteristics , control operation is started using the new parameters (5).
a
During phase 3, heating and cooling are done simultaneously!
Operation
KS 90-1 / KS 92-1 23 Self-tuning
t
+100%
Y 0%
-100%
X
W
t reversal
point
Start r
1 2
3
4 5
r t
t
2
100%
Y
0%
X
W
1 3
blinks
4
r t
Start r
t
2
100%
Y
0%
X
W
Start r
1 3 t reversal point
blinks
t
100%
Y
0%
X
W
start r
1 2 t reversal point
blinks