Which term describes the dependent variable in a process to be controlled?

• A. Process variable
• B. Manipulated variable
• C. Disturbance variable
• D. Setpoint variable

Answer: (A)

In a control loop, the value that the system measures and aims to regulate is the process variable. This is the output of the process that depends on inputs and any disturbances in the system. The controller uses the difference between the setpoint (the desired target) and the process variable to determine the manipulated variable, which is the control input adjusted to push the process variable toward the setpoint. Disturbance variables are external factors that affect the process but are not the variable being controlled, and the setpoint is the desired value itself, not the actual measured output. So the term that describes the dependent variable in a process to be controlled is the process variable.