Burkert 8624-2 Standard Instructions De Service page 31

Characteristics of PI controllers
A PI controller has a proportional and an integral fraction (P and I fractions).
P fraction:
Function:
y = K · x
p d
K is the proportionality index (amplification factor). It is the ratio of the controller
p
output range DY to the proportional range Dx .
d
Characteristic and step response of the P fraction of a PI controller
x
d
y
max
k *x
p d
y
0
y
x
min
d
∆x
Proportional range
d
Characteristic Step response
Characteristics:
A purely P controller works theoretically undamped, i.e. it is fast and hence
dynamically favourable. It has a residual control difference, i.e. it does not
completely eliminate the effects of disturbances and is thus relatively unfavourable
from a static viewpoint.
8624-2 Standard - 29