4.3.4
Examples for self-tuning attempts
4.3.5
(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 at-
tempt is finished and control to the
set-point is using the new parameters.
Start: at set-point
Heating power Y is switched off (
1
).
If the change of process value X was
constant during one minute and the con-
trol deviation is > 10% of
SP.Hi
-
SP.LO
(
2
), the power is switched on
(
3
). At the reversal point, the self-tu-
ning attempt is finished, and control to
set-point W is using the
new parameters.
4.4
Manual tuning
The optimization aid should be used with units on which the control parameters
shall be set without self-tuning.
For this, the response of process variable x after a step change of correcting varia-
ble y can be used. Frequently, plotting the complete response curve (0 to 100%)
is not possible, because the process must be kept within defined limits. Values T
g
and x
max
(step change from 0 to 100 %) or
∆
t and
∆
x (partial step response) can
be used to determine the maximum rate of increase v
max
.
Controller
Digital 280-1
Manual tuning
20
t
2
100%
Y
0%
X
W
start
r
1
3
t
turning point
blinks
lit
off
t
100%
Y
0%
X
W
start
r
1
2
t
turning point
blinks
lit
off
t
2
100%
Y
0%
X
W
start
r
1
3
t
turning point
blinks
lit
off
Summary of Contents for Digital 280-1
Page 48: ...12 Notes Notes Digital 280 1 48...
Page 49: ...Notes 49 Digital 280 1...
Page 50: ...Digital 280 1 50...
