What is the primary feature that distinguishes a closed-loop control system from an open-loop control system?

• A. The ability to handle higher power inputs
• B. The use of a feedback mechanism to correct errors
• C. The absence of measurement sensors
• D. The exclusive use of digital controllers

Answer: (B)

The primary feature that distinguishes a closed-loop control system from an open-loop control system is indeed the use of a feedback mechanism to correct errors. In a closed-loop system, the output is continuously monitored and compared to the desired setpoint. If there is any deviation or error, the system uses feedback to adjust its inputs accordingly. This closed-loop feedback helps maintain the desired performance and stability of the system by allowing it to respond to variations or disturbances in the environment.

For instance, consider a temperature control system in a furnace. A sensor measures the current temperature and sends this information back to the controller. If the temperature deviates from the setpoint, the controller can adjust the heating element to bring the temperature back to the desired level. This dynamic adjustment is critical for achieving accurate and reliable performance.

In contrast, open-loop systems lack this feedback mechanism. They operate based on predetermined instructions without adjusting for output changes, making them less adaptable to variations. The other options pertain to characteristics that may be present in different control systems, but they do not capture the essential distinction between closed-loop and open-loop systems regarding error correction.