Controller Functions; Pid Controller - Honeywell APT4000PH User Manual

Controller functions

PID controller

P controller
Application in integrating systems
(e.g. closed tank, batch processes).
PI controller
Application in non-integrating systems
(e.g. drains).
PID controller
The additional derivative action compensates for measurement
peaks.
Controller characteristic
+100 % Controller output Y P
[%]
Neutral zone Y P =0
Setpoint
-100 %
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[pH]
APT4000PH
Controller equations
Controller output Y = Y P +
P-action
Proportional action Y P
Setpoint - Meas. value
Y =
* K
P
C
Constant
Neutral zone (Y=0)
Tolerated deviation from setpoint.
The setting "1pH", for example, permits a deviation of ± 0.5 pH
from the desired value without activating the controller.
Proportional action (Gradient K
100 %
%
K = 500
C
50 %
X w 1 / (100)
Deviation
dY P
1
Y P dt + T D
T R
dt
I action
D action
with:
Y P Proportional action
T R Reset time [s]
T D Rate time [s]
K C Controller gain [%]
Constant 5 (for pH)
500 mV (for ORP)
[%])
C
%
K = 200
C
%
K = 100
C
%
K = 50
C
2 / (200) 3 / (300) 4 / (400)
(Process variables: pH / (mV))
5 / (500)
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