Endress+Hauser Liquisys M CPM253 - Page 45

Liquisys M CPM223/253 Commissioning
Endress+Hauser 45
Feedforward control to PID controller
For control systems with very short reaction times, it can be useful to also apply the flow rate,
if it is fluctuating, to the controller to optimize the control process.
Feedforward control is a multiplying function as illustrated in the figure below (example
with factory setting):
C07-CPM2x3xx-05-06-00-de-003.eps
Fig. 34: Multiplying feedforward control
YGain K
infl
X Current input signal [%]
C07-CPM2x3xx-05-06-00-xx-002.eps
Fig. 33: Sample arrangement for feedforward control of the flow in the main stream to the PID controller
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2
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4
Measuring water extraction point
Static mixer
Injection points
Flowmeter
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6
7
8
Alkali
Acid
Liquisys M CPM253
CPA250 with CPS11
CAL REL
REL1
REL1
ALARM
REL2
REL2
E
mg/l
25.0 °C
0.42
F
4 ... 20 mA
23
1 4
8
7
6
5
1
0 20 40 60 80 100Z7
1,5
0,5
Y
X