Fuji Electric FRENIC-HVAC User Manual page 542

Follow the procedure below to set data to external PID control function codes.
It is highly recommended that you adjust the external PID control value while monitoring the
system response waveform with an oscilloscope or equivalent. Repeat the following
procedure to determine the optimal solution for each system.
- Increase the data of function code J510/J610/J660 (External PID control P (Gain)) within
the range where the feedback signal does not oscillate.
- Decrease the data of function code J511/J611/J661 (External PID control I (Integral time))
within the range where the feedback signal does not oscillate.
- Increase the data of J512/J612/J662 (External PID control D (Differential time)) within the
range where the feedback signal does not oscillate.
Refining the system response waveforms is shown below.
1) Suppressing overshoot
Increase the data of function code J511/J611/J661 (Integral time) and decrease that of
J512/J612/J662 (Differential time).
2) Quick stabilizing (moderate overshoot allowable)
Decrease the data of J510/J610/J660 (Gain) and increase that of J512/J612/J662
(Differential time).
3) Suppressing oscillation whose period is longer than the integral time specified by function
code J511/J611/J661
Increase the data of J511/J611/J661 (Integral time).
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