Burkert 8630 Instructions De Service page 161

Correcting
variable Y
Actual value
Ks * ∆Y
Figure 8.8: Progression of the controlled variable after a manipulated variable change ∆ Y
Method:
• Set the controller to MANUAL mode
• Output a manipulated variable change and record the controlled variable with a recorder
• Switch off in good time if you encounter critical progressions (e. g. a risk of overheating).
Pay attention to the fact that, in thermally inert systems, the actual value of the controlled variable may
NOTE
increase further switching off.
The following table lists the settings for the controller parameters depending on Tu, Tg and Ks for command and disturbance response
and for an aperiodic control operation as well as a control operation with 20% overshoot. They apply to systems with a P response,
with a dead time and with a delay of the 1st order.
Parameter settings according to Chien, Hrones and Reswick:
Controller Aperiodic control operation
(0 % overshoot)
type
Command
P controller
Kp = 0,3
Kp = 0,35
PI control-
Tn = 1,2 Tg
ler
Kp = 0,6
PID con-
Tn = Tg
troller
Tv = 0,5 · Tu
The proportionality factor Ks of the controlled member is given according to Figure 8.8 by:
160
Tu Tg
Parameter settings
Control operation
with 20 % overshoot
Disturbance Command
Tg Tg
Kp = 0,3 Kp = 0,7
Tu*Ks Tu*Ks
Tg
Tg
Kp = 0,6 Kp = 0,6
Tu*Ks
Tu*Ks
Tn = 4 · Tu Tn = Tg
Tg Tg
Kp = 0,95 Kp = 0,95
Tu*Ks Tu*Ks
Tn = 2,4 · Tu Tn = 1,35 · Tg
Tv = 0,42 · Tu Tv = 0,47 · Tu
∆ X
Ks =
∆Y
t
Controlled
variable
t
Disturbance
Tg Tg
Kp = 0,7
Tu*Ks Tu*Ks
Tg Tg
Kp = 0,7
Tu*Ks Tu*Ks
Tn = 2,3 · Tu
Tg Tg
Kp = 1,2
Tu*Ks Tu*Ks
Tn = 2 · Tu
Tv = 0,42 · Tu
Operating instructions no. 800607