Value pH
6.00 7.00 8.00
Setpoint
Control variable
- 100 0 +100
Negative deviation
Positive control variable
Time
Time
A1472
Fig. 86: Control type PID monodirectional, pH-increasing direction
Adjustable parameters in the [Control] menu
Make the following selection in the Control
menu:
11.1 Control parameter [Type]
You set the controller type under the menu
option
[Type]
. You can set the
[Type]
as
[1-way]
or
[2-way]
.
P, PI, PID controllers are continuous control‐
lers. The control variables can take any value in
the control range from -100 % … +100 %.
P controller:
This controller type is used with an integrating
control path (e.g.
[Batch Neutralisation]
). If the
control deviation becomes small then the con‐
trol (actuation) of the actuator becomes smaller
(proportional relationship). If the setpoint is
nearly reached, then the control output is nearly
0 %. However the setpoint is never exactly
reached. Consequently a permanent control
deviation results. When stabilizing large
changes, excess oscillations may occur.
Setting the
[Control]
127
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