Red Seal Instrumentation and Control Technician Practice Exam

In terms of feedback, how do open-loop and closed-loop control systems differ?

1. Open-loop uses feedback, closed-loop does not

2. Closed-loop systems are less efficient

3. Open-loop systems use external sensors, closed-loop do not

4. Closed-loop systems use feedback to adjust control actions

The correct answer is: Closed-loop systems use feedback to adjust control actions

Closed-loop control systems are designed to utilize feedback to continuously monitor the output of the system and make necessary adjustments to control actions. This feedback mechanism allows the system to respond to changes and disturbances effectively, ensuring that the desired output is achieved and maintained. For instance, in a temperature control system, a closed-loop system would use a temperature sensor to measure the current temperature, compare it to the desired setpoint, and adjust the heating or cooling action accordingly. In contrast, open-loop control systems do not utilize feedback. They operate based on predefined settings and outputs without any mechanisms to measure or adjust based on the actual performance of the system. Because they lack the ability to correct errors or adjust to changes in environment or conditions, open-loop systems may be less reliable in scenarios where variability is common. The efficiency of closed-loop systems is often enhanced due to this feedback mechanism, allowing for real-time adjustments that help maintain performance within desired parameters. Therefore, closed-loop systems are generally considered to provide greater accuracy and reliability compared to their open-loop counterparts.