What does the term “process variable” refer to?

The term "process variable" specifically refers to the actual value of the quantity being controlled within a process. This is a fundamental concept in control systems, as it represents the current state of the process that is being monitored and regulated. For example, in a temperature control system, the process variable would be the actual temperature measured in the system.

Understanding the process variable is crucial for effective control because it is compared against the set point or desired target value to identify any discrepancies. This comparison helps the control system adjust its outputs to minimize the difference and maintain the desired performance of the system. Monitoring the process variable allows operators and automated systems to take corrective actions as necessary, ensuring the process remains stable and efficient.