Question 35 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is D **Why option D ("Feedback") is correct:** Feedback is the fundamental concept in a closed-loop control system where the output (actual result) of a system is measured, compared against the desired input (setpoint), and the resulting difference (error) is used to adjust the system's operation. This corrective action drives the actual result closer to the desired result, which is precisely the action described in the question. **Why the other options are incorrect:** * **A) Deadband:** A deadband is a specific range or region around the setpoint where no control action or adjustment is taken. It is used to prevent the controller from constantly adjusting due to minor noise or variations, not the general principle of using the error for correction. * **B) Gain:** Gain (or controller gain) is a parameter that defines the proportional relationship between the measured error and the corrective action applied by the controller. It quantifies *how much* correction is applied, but it is not the name for the overall action of measuring and correcting. * **C) Instability:** Instability is an undesirable condition in a control system where the output oscillates uncontrollably or diverges over time. It is a negative outcome that can result from excessive gain or poor tuning, not the mechanism used to drive the result toward the desired setpoint.