Endress+Hauser Liquisys M CUM223, Руководство по эксплуатации

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Liquisys M CUM223/253 Commissioning
Hauser 49
P(ID) controller
You can define various controller functions for the transmitter. On the basis of the PID
controller, P, PI, PD and PID controllers can be implemented. For an optimum control system,
use the controller that best suits your application. Depending on the option selected in the
R 237/R 266 field, the actuating signal can be output via relays or via current output 2 (if
available).
•
P controller
Used for simple linear control purposes with small system deviations. Where major
changes are to be controlled, overshooting may occur. In addition, a lasting control
deviation is to be expected.
• PI controller
Is used for control systems where overshooting is to be avoided and no lasting control
deviation should occur.
• PD controller
Is used for processes that require quick changes and where peaks are to be corrected.
• PID controller
Is used for processes where a P, PI or PD controller does not control sufficiently.
Configuration options of the PID controller
The following configuration options are available for a PID controller:
• Change control gain K
p
(P influence)
• Set integral action time T
n
(I influence)
• Set derivative action time T
v
(D influence)
Basic load dosing (Basic)
The basic load dosing (field R231) is used to set a constant dosage (field R2311)
PID controlling plus basic load dosing
If you select this function (PID + Basic) in field R231 the PID controlled dosage will not be
lower than the basic load value entered in field R2311.
a0008940
Fig. 26: Control characteristic PID controller with basic load dosing
A PID with basic load
B Basic load
C PID
Commissioning
If you do not yet have any experience for setting the control parameters, set the values that
yield the greatest possible stability in the control circuit. Proceed as follows to optimize the
control circuit further:
• Increase the control gain K
p
until the controlled variable just starts to overshoot.
• Reduce K
p
slightly and then reduce the integral action time T
n
so that the shortest possible
correction time without overshooting is achieved.
• To reduce the response time of the controller, also set the derivative action time T
v
.
100 %
100 %
A
B
C