The ultimate sensitivity method ( Figure 300-24) is also a closed loop test. Adjust the integral time and/or the derivative time to their minimum values.…

# Category: Process Control

The quarter decay method is a closed loop controller tuning method. This means that the controller remains in automatic while tuning adjustments are made. The…

Feed-forward control measures a disturbance before it can affect the controlled variable, and changes the manipulated variable to compensate for the disturbance. Of course, for…

Cascade control should also be considered when the primary control variable is slow to react to disturbances. Like any feedback control loop, a cascade control…

With derivative action (also called rate action), the controller output is proportional to the rate of change of the error. This means the faster the…

Integral time should be proportional to the time it takes for the process to respond to control action. When the process responds quickly, the integral…

A basic problem with integral controllers is that integral action continues as long as an error exists. Assume a proportional-plus-integral controller is used to maintain…

Proportional-plus-integral control is the recommended control action for most applications. Often called PI control, it combines proportional action and integral action in one controller. The…

Integral (reset) action is the result of an integration of controller error with time. With integral action, controller output is proportional to both the size…

(Controller output can go directly to a valve or to the setpoint of another controller. In the following discussions, it is assumed that controllers send…