CLASSIFICATIONS OF CONTROL SYSTEMS – Process Control
Process control refers to a control system that oversees some industrial process so that a uniform, correct output is maintained. It does this by monitoring and adjusting the control parameters (such as temperature or flow rate) to ensure that the output product remains as it should.
Figure 7 A closed-loop oven-heating system.
The classic example of process control is a closed-loop system maintaining a specified temperature in an electric oven, as illustrated in Figure 7. In this case, the actuator is the heating element, the controlled variable is the temperature, and the sensor is a thermocouple (a device that converts temperature into voltage). The controller regulates power to the heating element in such a way as to keep the temperature (as reported by the thermocouple) at the value specified by the set point.