192
Supplementary information
Type 8792, 8793 REV.2
26.3.2 Adjustment rules according to Chien, Hrones and Reswick
(Actuating Variable Jump Method)
With this method the controller parameters are adjusted on the basis of the transient behavior of the controlled
system. An actuating variable jump of 100% is output. The times Tu and Tg are derived from the progress of
the actual value of the control variable.
Progress of the control variable following an actuating variable jump
∆
Y
Actuating
variable Y
Ks
⋅∆
Y
Actual value
∆X
Tu
Tg
Control variable
t
∆Y
t
Figure 78:
Progress of the control variable, actuating variable jump
Procedure
→
Switch controller to MANUAL (MANU) operating state
→
Output the actuating variable jump and record control variable with a recorder
→
If progresses are critical (e.g. danger of overheating), switch off promptly.
Note that in thermally slow systems the actual value of the control variable may continue to rise
after the controller has been switched off.
In the following “Table 134” the set values have been specified for the controller parameters, depending on
Tu, Tg and Ks for reference and disturbance reaction, as well as for an aperiodic control process and a control
process with a 20% overshoot. They apply to controlled systems with P-behavior, with dead time and with
a delay of the first order.
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