Burkert 8630 Operating Instructions Manual page 134

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).
NOTE Pay attention to the fact that, in thermally inert systems, the actual value of the controlled variable may
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
As shown in the figure of the previous page, the proportional action coefficient Ks of the control system can be calculated by way
of the increase in the inflectional tangent, i. e. by way of ∆X / ∆t (∆Y: manipulated variable change):
134
Actual value Istwert
Ks•∠ Y
T u
Parameter settings
Disturbance
Tg Tg
Kp = 0,3
Tu*Ks Tu*Ks
Tg
Tg
Kp = 0,6
Tu*Ks
Tu*Ks
Tn = 4 · Tu
Tg Tg
Kp = 0,95
Tu*Ks Tu*Ks
Tn = 2,4 · Tu
Tv = 0,42 · Tu
∆X * Tg
Ks =
∆t * ∆Y
∠ x
∠ t
∠ x
∠ t
T g
Control operation
with 20 % overshoot
Command Disturbance
Tg Tg
Kp = 0,7 Kp = 0,7
Tu*Ks Tu*Ks
Tg Tg
Kp = 0,6 Kp = 0,7
Tu*Ks Tu*Ks
Tn = Tg Tn = 2,3 · Tu
Tg Tg
Kp = 0,95 Kp = 1,2
Tu*Ks Tu*Ks
Tn = 1,35 · Tg Tn = 2 · Tu
Tv = 0,47 · Tu Tv = 0,42 · Tu
Zeit
Time
Operating instructions no. 800607