Page 102 Accumass BW500 PL-565
PID Control
8. Again observe the oscillation of the control output. Compare results to the figures 4,5
and 6 below.
Figure 4
Figure 5
Figure 6
9. The D term is not critical in typical shearing type weigh feeder applications. The
purpose of the D term is to anticipate where the process is heading by looking at the
time rate and direction of change of the process variable. The D term becomes very
useful in applications where the material control point is far away from the measuring
point. An example of this would be a weigh belt or conveyor with a belt scale
SETPOINT
I term is correctly set
SETPOINT
SETPOINT
I term is too high
I term is too low
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