
4Ć68 FST Configuration
Original Ć June 1990CE4.2:CL6211
DTC DTC
26
INSTRUCTION NAME: DTC (dead time compensation)
DESCRIPTION:
This instruction provides feedback control for a loop with significant transport
delay, based on actual process dead time, gain, and lag time. DTC provides a process model that
simulates the expected response of the process. By predicting the process response, the loop can
be tuned as though the process has no significant transport delay. The dead time compensation is
based on a linear process variation to a change in valve output. The SVA and SVD inputs remain
unchanged. DTC can be used in conjunction with GCI and CASC.
The DTC function can be used in the same FST loop with the following PCA types only:
H PI/PID/I
H Error-squared PI/PID
H Notch Gain PI/PID
H Adaptive Gain PI/PID
GRAPHIC REPRESENTATION: SYMBOLIC REPRESENTATION:
100%
0
INPUT
OUTPUT
SET POINT
PROCESS
VARIABLE
PI
n
t
0
t
1
ttt
4
32
50%
100%
0
50%
t
0
t
1
tt t
4
32
63%
n
e
f(t)
2
f(t)
1
-
+
+
+
+
-
f(t)
1
f(t)
2
= LAG
= DEADTIME
(Continued on next page)
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