bürkert 8624-2 Betriebsanleitung Seite 72

I-portion:
Function:
y =
Ti is the integral or rotation time. This is the time that passes while the manipulated
variable runs through the complete control range if the regulation deviation is kept
at 100%..
Characteristic and step response of the I-portion of a PI regulator
Regulating range ∆x
Characteristic
Characteristics
A pure I regulator completely removes the effects of interference. It therefore
possesses a favourable static behaviour. On the basis of its final setting speed, it
works more slowly than the P regulator, and tends to oscillate. It is therefore
relatively unfavourable from a dynamic point of view.
Superimposition of the P and I portions
For a digital regulator with a sensing time T
y = K
y : variable
K : amplification factor
p
x : control deviation (x
d
T : sensing time
A
T : integral action time
N
Operating Instructions No. 803 180
1
∫ ∫ ∫ ∫ ∫ x
dt
T
d
i
x
x
d
y
max
x
d
y
min
c
Step response
, on e can write with T
A
∑ ∑ ∑ ∑ ∑ x
(x + T /T )
p d A N d
= w - x)
d
Integral timeT
i
=K /T :
i p N
71