Burkert Type 1067 - Manual (Page 91)

POSITIONER 1067
E-39-
Y
Xd
Y0
Ymax
Ymin
Xd
Y
APPENDIX
A1: Characteristics of PID controllers
A PID controller has a proportional, an integral and a differential component (P, I and D components).
P component :
Function : Y = Kp • Xd
Kp is the proportional action coefficient. It results from the ratio of the manipulating range ΔY to the
proportional range ΔXd.
t
t
X
Y
Xd
Kp.Xd
Kp. Xd
1
Ti
Characteristic Step response
Characteristics :
Theoretically, a pure P controller operates without delay, i. e. it is fast and therefore dynamically favorab-
le. It has a lasting system deviation, i. e. it does not balance out the effects of disturbances completely
and is therefore relatively unfavorable from the static point of view.
I component :
Function : Y = ƒ Xd dt
Ti ist the integration or manipulating time. This is the time that elapses before the manipulated variable
has passed through the complete manipulating range.
Manipulat- ing rang
e
Proportional range