Siemens MICROMASTER 420 Reference Manual page 23

Figure 2-5
Figure 2-6
The values of P2280 and P2285 will be determined by the relationship between
motor frequency and the PI control quantity (e.g. pressure).
When optimizing a control process we would recommend using an oscilloscope to
monitor the feedback signal to see the system response. The analogue output can
be used for this by setting P0771 = 2266. Most commonly small PI setpoint step
changes (1- 10%) without the PI ramp times (P2257 = P2258 = 0.0 s) are used to
evaluate the system response. Once the desired response profile has been
achieved, the operational ramp times are then set.
If you are optimizing without an oscilloscope we suggest starting with a small P
term (e.g. P2280 = 0.20) and adjusting the I term until stable operation constant
achieved. A small PI setpoint change should then be given and depending on the
system response the parameters adjusted according to the tendencies shown in
the figures above.
MICROMASTER 420 Reference Manual
Issue A1
Quick response with overshoot, but instability:
P2280 = 0.55; P2285 = 0.03 s
Damped response: P2280 = 0.20; P2285 = 0.15 s
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