True or False: In a closed-loop system, the controlled variable is rarely measured.

In a closed-loop system, the controlled variable is continuously monitored and measured to ensure that the system maintains the desired output or performance. The essence of a closed-loop system lies in its feedback mechanism, where the actual value of the controlled variable is compared to the setpoint or desired value. This comparison allows the system to make real-time adjustments based on the feedback received, ensuring stability and accuracy in performance.

The measurement of the controlled variable is crucial for the effective operation of the system, as it informs the controller how far off the current state is from the desired state. Without this measurement, the control system would not be able to respond appropriately to any disturbances or changes in conditions, leading to potential inefficiencies or failures.

Considering this, the assertion that the controlled variable is rarely measured in a closed-loop system is false. Instead, it emphasizes the importance of measurement and feedback, which are foundational principles for closed-loop control systems. This is why the correct answer is that the statement is false.