Deif Multi-line 2 Designers Reference Handbook page 128

AGC
Integral regulator
To illustrate the integral action coefficient, the KI reset time can be used. The reset time is
defined as the time the integral regulator uses to replicate the momentary change of the output
caused by the proportional regulator.
In the drawing below the proportional regulator causes an immediate change of 2.5mA. The
reset time is then measured when the output reaches 2 x 2.5mA = 5mA.
The drawing shows that when the KI setting is changed to half the value, then the reset time is
doubled. The reset time is 10 seconds with a KI setting of 100. With the KI setting adjusted to 50
the reset time will be 20 seconds. The KP setting is 100 in this example.
6
5
4
3
mA
2
1
0
0
The reset time of the unit can be calculated at all values of KP and KI with the formula:
The table shows theoretical reset times in seconds:
k 1
I
k
P
1 10
10 100
100
1000
1000
10000
DEIF A/S
Reset time, t
KI = 100
5 10 15
sec
=
t k *
N
P
10
1
10
100
1000
Designer's Reference Handbook
N
KI = 50
20 25
10 / k
I
100
0.1
1
10
100
30 35
1000
0.01
0.1
1
10
Page 128 of 168