Watlow PPC-2000 - Manual (Page 250)

Chapter 6: Tuning and Control PPC-2000 User’s Guide
222 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Proportional and Integral Control
With proportional and integral control, the integral term
corrects for offset by repeating the proportional band’s error
correction until there is no error. For example, if a process
tends to settle about 5°F below the set point, appropriate
integral control brings it to the desired setting by gradually
increasing the output until there is no deviation.
Figure 6.3 Proportional and Integral Control
Proportional and integral action working together can bring a
process to setpoint and stabilize it. However, with some
processes the user may be faced with choosing between
parameters that make the process very slow to reach setpoint
and parameters that make the controller respond quickly, but
introduce some transient oscillations when the setpoint or load
changes.
PB
SP
PV