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SC100/200 Series Users Manual EM-6337-B Rev.15
9.4. MANUAL ADJUSTMENT OF PID PARAMETERS FOR FINE TUNING
Parameters obtained by auto-tuning may not be the most appropriate. Run an actual control operation with them and conrm
their adequacy. When further manual adjustments are needed, refer to the following instructions.
Proportional Band (PB)
Set a larger PB when the system allows more time to track SP but less overshooting.
Set a smaller PB when the system allows more overshooting but less time to stabilize, or when it needs to recover more
quickly from a disturbance.
Be aware that the output signal may start hunting if you choose too small a proportional band.
Integral Time (TI)
Repeating overshooting/undershooting or hunting of long cycles suggests the integral action may be too intensive. Set a
larger TI or a larger PB to minimize hunting.
Derivative Time (TD)
Hunting of short cycles suggests too fast a response time of the control system and the derivative action may be too inten-
sive. Set a smaller TD in such cases.
SP
PV
t
Small PB
Large PB
SP
PV
t
Small TI (Small PB)
Large TD
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