Azbil DCP31 - Page 151

7-41
Chapter 7. PARAMETER SETUP
No. Item Code Item
Factory
Setting
User
Setting
Setting
31
P -4
Proportional band
(PID set 4)
100.0  • Increasingtheratetime(
D
,
D D
) allows
overshoot to be inhibited more easily.
However, it also make hunting more
likely to occur as the controller reacts
to minute changes in PV.
In a temperature control system, set-
ting the rate time to
1
/
3
to
1
/
4
of the in-
tegrating time is generally considered
to be appropriate. In a pressure or ow
rate control system, derivative action
causes hunting.
Either set the
D
setting to 0.0 to disable
derivative action, or decrease the set-
ting so that derivative action is almost
negligible. The latter solution is more
frequently adopted.
 • TheMVupperandlowerlimits(
O L
,
O H
) function as integrating limits.
When the MV reaches the upper or
lower limit, integration no longer func-
tions. This prevents reset wind-up that
occurs when the PV has not risen for a
long time.
 • Manualreset(
R E
) is a setting for
eliminating oset that occurs during
proportional action (integrated action
disabled). For manual reset, set the MV
ideal for deviation 0.
 • Increasingthebrake(
B R
) value
increases the overshoot inhibit eect.
However, it also lengthens the rise
time.
32
1 -4
Reset time
(PID set 4)
0
33
D -4
Rate time
(PID set 4)
0
34
O L -4
MV lower limit
(PID set 4)
0.0
35
O H -4
MV upper limit
(PID set 4)
100.0
36
R E -4
Manual reset
(PID set 4)
50.0
37
B R -4
Brake
(PID set 4)
0
38
D P -4
Disturbance inhibit
proportional band
(PID set 4)
100.0
39
D I -4
Disturbance inhibit
reset time
(PID set 4)
120
40
D D -4
Disturbance inhibit
rate time
(PID set 4)
0
41
P -5
Proportional band
(PID set 5)
100.0
42
1 -5
Reset time
(PID set 5)
0
43
D -5
Rate time
(PID set 5)
0
44
O L -5
MV lower limit
(PID set 5)
0.0
45
O H -5
MV upper limit
(PID set 5)
100.0
46
R E -5
Manual reset
(PID set 5)
50.0
47
B R -5
Brake
(PID set 5)
0