Siemens Milltronics BW500 Operating Lnstructions page 85

Figure 5
Figure 6
D
9. The term is not critical in typical shearing type weigh feeder applications. The
purpose of the
time, rate, and direction of change of the process variable. The
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 (constant speed) being fed from a pre-feeder some distance or more than a
few seconds process time from the scale.
A properly set
in figure 6. A
D
the term, or set too low, shows no effect on the system.
10. The above closed loop cycling procedure allows ease in start up, but final
adjustments may be necessary in actual process operation.
7ML19985DK05Milltronics BW500 and BW500/L - OPERATING INSTRUCTIONS
I term is too low
I term is correctly set
D
term is to anticipate where the process is heading by looking at the
D
term will make the initial oscillations around the setpoint smaller, as
D
term set too high induces high oscillations, as in figure 4. Omission of
SETPOINT
SETPOINT
D
term becomes very
Page 79