Which situation describes an open-loop system's behavior under a heavy load?

• A. Output remains unaffected due to compensation
• B. Output adapts automatically via feedback
• C. Output may drift from the setpoint because there is no feedback
• D. System shuts down

Answer: (C)

Open-loop control relies on a pre-set input with no measurement of the actual output. When a heavy load is applied, this disturbance changes the system’s behavior, and because there’s no feedback to compare the output to the desired setpoint and then adjust the input, the output tends to drift away from the target. In other words, without sensing and correction, the system can’t compensate for the added load.

This is different from a feedback (closed-loop) system, which continuously measures the output and makes automatic adjustments to bring the output back to the setpoint. That’s why statements about automatic adaptation via feedback describe closed-loop behavior, not open-loop. The idea of the output remaining unaffected due to compensation or the system shutting down aren’t inherent to open-loop behavior under heavy load; they imply other mechanisms or fault conditions that aren’t the typical open-loop response.