Shimaden SR253 Series, Instruction Manual

Page: 31 / 64

1) Setting of proportional band (P) (Group 3-1A~)
A rate (%) of a change in control output to measuring range is set. Control output changes in proportion to difference (deviation) between measured
(PV) value and set (SV) value.
The wider the proportional band, the smaller the change in control output. The narrower the proportional band, the larger the control output.
Nevertheless, too narrow a proportional band causes control to oscillate (hunting), with the control result resembling ON-OFF action. When OFF is
set for proportional band, ON-OFF control is carried out.
Note 1: When OFF is selected for P, auto tuning cannot be executed.
2) Setting of action hysteresis (DF) (Group 3-1A~)
Setting P=0 (OFF) starts ON-OFF control. Setting action hysteresis (DF) between ON and OFF at that time works to avoid chattering or the like and
to stabilize control.
3) Setting of integral time (I) (Group 3-1A~)
This is the function to correct offset (constant deviation) caused by proportional action. The longer the integral time, the weaker the correcting action
and vice versa. Nevertheless, too short an integral time causes integral hunting, with the control results showing oscillation.
4) Setting of differential time (D) (Group 3-1A~)
A change in control output is estimated; overshoot due to integration is suppressed; and stability of control is improved.
The shorter the differential time, the weaker the differential action and vice versa. If it is too long, however, the control result may oscillate.
Note 1: Even when auto tuning is executed with D=OFF, D=OFF remains unchanged.
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PID 1 P
1
: 3.0%
I
1
: 120s D
1
: 30s
MR: 0.0%
Zone: 0.0
°
C
↓
Setting range: OFF, 0.1~999.9%
Initial value: 3.0%
PID 1 P
1
: OFF
DF
1
: 2.0 ° C
Zone: 0.0 ° C
↓
Setting range: 1~9999 unit
Initial value: 20 unit
ON
DF
L H
OFF
Setting point
PID 1 P
1
: 3.0%
I
1
: 120s D
1
: 30s
MR: 0.0%
Zone: 0.0
°
C
↓
Setting range: OFF, 1~6000 sec.
Initial value: 120 sec.
PID 1 P
1
: 3.0%
I
1
: 120s D
1
: 30s
MR: 0.0%
Zone: 0.0
°
C
↓
Setting range: OFF, 1~3600 sec.
Initial value: 30 sec.