Instruction Manual

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.