Table 17-5. Easy-Tune Equations - ABB ControlIT 53MC5000 Instruction Manual

17.5 MODIFICATIONS TO TUNING CRITERIA
During EASY-TUNE sequence execution, each of the three algorithm variables: Time Constant
(T ), Process Gain (K
P P
(controller operating characteristics would be slower response, but less chance of oscillation and
instability) before the tuning parameters are computed using the ITAE equations listed in Table
17-5. (Figure 17-2 illustrates the equation variables with respect to the response curve.) The
three variables T , K , and W
p P
are more conservative or decreased for less conservative tuning parameter calculations (controller
operating characteristics would be faster response and greater chance of instability or oscillation).
Parameters used to alter the variables are the EASY-TUNE Modifiers, datapoints C382 (T
fier), C383 (D Modifier), and C384 (W
P
C382, C383, and C384 be between -0.5 and 0.5. The effect on the equation variables is as follows:
T modified = T (1 - C382)
P P
K modified = K (1+ C383)
P P
W modified = W (1+ C384)
P P

Table 17-5. EASY-TUNE Equations

Mode PB in %
P 204K (W
P
PI 116.4K (W
P
PID 73.69K (W
P
PD** 54.02K (W
P
I**
Note: Process characteristics T
aDOrding to the Minimum Integral of Absolute Error Multiplied by Time Criterion (ITAE) for P, PI,
and PID modes.
*If computed to be < B003/50, then T
**Empirical estimates, not based on ITAE method.
Section 17. EASY-TUNE
), and Dead-Time (W
P
can be increased numerically to compute tuning parameters that
P
Modifier). It is recommended that the values entered in
P
1.084
/T )
P P
0.977
/T ) (T
P P P
0.947
/T ) (T
P P P
0.947
/T )
P P
0 T [(K
P
, K , and W
P P P
= 0.
D
) are altered by 10% in the conservative direction
TR (Minutes)
0
0.68
/40.44)(W /T )
P P
0.738
/51.02)(W /T )
P P
0
0.15
/25)(W /T ) ]
P P P
are used to compute the ideal tuning parameters
Modi-
P
TD* (Minutes)
0
0
0.995
(T /157.5)(W /T )
P P P
0.995
(T /157.5)(W /T )
P P P
0
17-5