Burkert Type 8635 User Manual
Page 152
150 - 8635
G
ENERAL
R
ULES
(A
PPENDIX
)
Curve of the controlled variable after a step in controller output
∆∆∆∆∆Y
Procedure
• Switch controller to MANUAL
• Deliver a step in controller output and register the controlled variable with a chart recorder
• With critical runs (e.g. on risk of overheating), switch off in good time.
In the following table, the setting values are given for the controller parameters as a function of Tu, Tg
and Ks for command and disturbance behaviour, as well as for an aperiodic control event and a control
event with 20% overswing. They apply for members with P behaviour, with dead time and with first-order
delay.
Adjustment rules of Chien, Hrones and Reswick
(controller output step method)
With this method the controller parameters are set on the basis of the transient behaviour of the
controlled member. A step in the controller output of 100 % is delivered. The times Tu and Tg are derived
from the curve of the actual value of the controlled variable.
t
Actual
value
∆
Y
Controller
output Y
∆
X
Ks *
∆Y
t
Controlled
variable
Tu
Tg
NOTE
It should be observed that with thermally sluggish systems, the actual value of the
controlled variable may continue to rise after switching off.