West Control Solutions Pro-8 - Manual (Page 22)

3.5.8 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
attempt is finished and the new para-
meter 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),
the controller outputs a reduced cor-
recting variable pulse (max. 20%)
(2). After determination of the con-
trol parameters using the process cha-
racteristic (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 hea-
ting power is switched on (1). Heating
parameters
Pb1, ti1, td1 and t1
are determined at the reversal point. The
process is controlled to the set-point (2).
With constant control deviation, the con-
troller provides a cooling correcting va-
riable pulse (3). After 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
Self-tuning 22
Pro-8
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
t
2
100%
Y
0%
X
W
1 3
blinks
4
r t
Start r
t
+100%
Y 0%
-100%
X
W
t reversal
point
Start r
1 2
3
4 5
r t