Which statement best describes the setpoint?

• A. The actual value measured by a sensor
• B. A desired value that is to be controlled in a process
• C. The maximum system capacity
• D. The rate of change of the process variable

Answer: (B)

Setpoint is the desired value the control system aims to maintain for the process variable. It serves as the reference input that the controller uses to compute error by subtracting the actual measured value from this target. The controller then adjusts the manipulated variable to reduce that error and move the process toward the setpoint. The actual value measured by a sensor is called the process variable, not the setpoint. The maximum system capacity describes the upper limit of what the system can handle, not the target value. The rate of change of the process variable describes how quickly the variable is changing, which is a separate signal, not the target value. Setpoints can be fixed or time-varying to follow a desired process profile.