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Keep in mind that after changes in the P-band, the process can take a very long time
to become consistent again, especially with sluggish processes. Manual adjustment
can take from a few minutes to several hours.
In the flowchart, PBu is the ultimate P-band, Tu is the ultimate period
If both values are equal, we speak of the critical-stable state (see picture).
Critical steady state
If the control result after manual adjustment according to the flow chart still does not
provide a satisfactory result, the following rules can be applied:
Setting sequence
1. proportional band (P)
PB1 and/or PB2
2. integral time (I)
TI1 and/or TI2
3. difference time (D)
TD1 and/or TD2
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Symptom
Slow response
High oversteer or
oscillation
Slow response
Unstable or oscillating
Slow response or
oscillation
High oversteer
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Solution
Reduce PB1 or PB2
Increase from PB1 or
PB2
Reduce TI1 or TI2
Increase from TI1 or TI2
Reduce TD1 or TD2
Increase from TD1 or
TD2
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