Burkert Type 8793 - Manual (Page 247)

247
Additional technical information
41.2. 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 141: 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 132” the adjustment 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.
english
Type 8792, 8793