Manual Self-Tuning - WEST 8800 Operating Manual

Operation

3.6 Manual self-tuning

The optimization aid can be used with units on which the control parameters shall
be set without self-tuning.
For this, the response of process variable x after a step change of correcting
variable y can be used. Frequently, plotting the complete response curve (0 to
100%) is not possible, because the process must be kept within defined limits.
Values T
g
response) can be used to determine the maximum rate of increase v
y
100%
Y h
0%
x
X max
y
Y
h
Tu
Tg
X
max
V
max
The control parameters can be determined from the values calculated for delay
time T , maximum rate of increase v
u
according to the formulas given below. Increase Pb1, if line-out to the set-point
oscillates.
Manual self-tuning
and x (step change from 0 to 100 %) or ∆t and ∆x (partial step
max
Tg
Tu
= correcting variable
= control range
= delay time (s)
= recovery time (s)
= maximum process value
Xmax ∆ x
= = = max. rate of increase of process value
Tg ∆ t
t
{X
{t
t
, control range X
max
24
.
max
and characteristic K
h
8800 process controller