Red Seal Instrumentation and Control Technician Practice Exam

What type of control system would be characterized by not using feedback?

1. Closed-loop control system

2. Open-loop control system

3. Adaptive control system

4. Feedback control system

The correct answer is: Open-loop control system

An open-loop control system is characterized by its lack of feedback. In such a system, the control action is performed based on predefined commands or input without adjusting for the actual output. This means that the system does not measure or respond to the output conditions, which differentiates it from closed-loop systems where feedback is continuously monitored to make corrections to the input if necessary. This type of system is often simpler and less expensive to implement because it doesn't require sensors or mechanisms to compare the output to the desired setpoint. Open-loop control can work effectively in situations where the relationship between the input and output is well understood and predictable, allowing for consistent performance without real-time adjustments. Examples include a washing machine running a timed cycle with no ability to adjust based on the cleanliness of the clothes or a sprinkler system designed to turn on at set times regardless of weather conditions. The other types of systems mentioned include closed-loop and feedback systems, both of which utilize feedback to enhance performance. Adaptive control systems involve changes based on feedback as well, focusing on improving control as circumstances change.