Instruction manual

The PBu is called the and the period of oscillation Tu is called
the in the flow chart of Figure 3.23 . When this occurs, the
process is called in a . Figure 3.24 shows a critical steady
Ultimate P Band
Ultimate Period
critical steady state
The PBu is called the and the period of oscillation Tu is called
the in
the flow chart of Figure 3.23 . When this occurs, the
process
is called in a.Figure 3.24 shows a critical steady
Ultimate
P Band
Ultimate
Period
critical
steady state
Set pointSet point
Tu
PV
Time
If PB=PBu
the process sustains to oscillate
If PB=PBu
the
process sustains to oscillate
Figure 3.24 Critical Steady
State
Figure 3.24 Critical Steady
State
If the control performance by using above tuning is still unsatisfactory, theIf the control performance by using above tuning is still unsatisfactory, the
ADJUSTMENT SEQUENCEADJUSTMENT SEQUENCE
SYMPTOM SOLUTION
(1) Proportional Band(P)
PB1 and/or PB2
(1) Proportional Band ( P )
PB1
and/or PB2
(2) Integral Time(I)
TI1 and/or TI2
(2) Integral Time ( I )
TI1
and/or TI2
(3) Derivative Time(D)
TD1 and/or TD2
(3) Derivative Time ( D )
TD1
and/or TD2
Slow ResponseSlow Response
High overshoot or
Oscillations
High overshoot or
Oscillations
Slow ResponseSlow Response
Slow Response or
Oscillations
Slow Response or
Oscillations
Instability or
Oscillations
Instability or
Oscillations
High OvershootHigh Overshoot
Decrease PB1 or PB2Decrease PB1 or PB2
Increase PB1 or PB2Increase PB1 or PB2
Decrease TI1 or TI2Decrease TI1 or TI2
Increase TI1 or TI2Increase TI1 or TI2
Decrease TD1 or TD2Decrease TD1 or TD2
Increase TD1 or TD2Increase TD1 or TD2
Table 3.2 PID Adjustment GuideTable 3.2 PID Adjustment Guide
Figure 3.25 shows the effects of PID adjustment on process response.Figure 3.25 shows the effects of PID adjustment on process response.
Figure 3.25 Effects of PID
Adjustment
Figure 3.25 Effects of PID
Adjustment
PV
Time
P actionP action
Perfect
PB too high
PB too high
PB too lowPB too low
Set pointSet point
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