Watlow MICRODIN - Manual (Page 40)

4 . 8 Wa t l o w M i c r o D I N
Proportional Control
Some processes need to maintain a temperature or process value closer to the
set point than on/off control can provide. Proportional control provides closer
control by adjusting the output when the temperature or process value is within
a proportional band. When the value is in the band, the controller adjusts the
output based on how close the process value is to the set point: the closer to set
point the lower the output. This is similar to backing off on the gas pedal of a
car as you approach a stop sign. It keeps the temperature or process value from
swinging as widely as it would with simple on/off control. However, when a
system settles down, the temperature or process value tends to “droop” short of
the set point.
The proportional band can be viewed or changed with Propband (PID Group). To
only view the proportional control value use Proportional Term (PID Group).
Figure 4.8 — Proportional Control
Features
Time
Temperature
Set Point
Proportional Band Droop
Overshoot