ABSTRACT
In the usual process control, a feedback control system is widely used. In such a system, information about the variable to be controlled is obtained from the transducer, and the controller then calculates the difference between the desired set point (SP) and the current process value (PV) as measured. It then calculates the output signal, which drives the actuator of the control valve for manipulating the appropriate streams for necessary correction. Such a control system is presented in Figure 4.1.
