Most controls required in process engineering can be performed with a controller with PI action.
With slower controlled systems with a longer delay time, e.g. temperature controls, the control can
be better implemented by a controller with a PID action.
Controllers with PI and PID actions have the advantage that following the transient condition, the
controlled variable does not deviate from the setpoint. The disadvantage is that the controlled
variable overshoots the setpoint before it settles.
If the controller parameters are well matched, combinations of PD and PID structures provide a
good control action and good response to disturbances, approach the setpoint without overshoot
and control without system deviation once the control point has been reached.
IP244
C79000–B8576–C860–02
Notes on Controller Settings
4–133