Question 70 MODE01 - Chief MODU Engineer

The Correct Answer is D **Explanation for why Option D ("gover governor over-control") is correct:** Governor hunting refers to a sustained oscillation (or cyclical movement) in the engine speed, typically accompanied by the continuous movement of the fuel rack or throttle. This instability occurs when the governor is too sensitive or "too aggressive" in responding to a speed change. If the governor's compensating mechanisms (like the proportional gain or reset time) are set too high, the governor will over-correct the initial speed error, causing the speed to overshoot the set point. The governor then corrects in the opposite direction, again overshooting. This constant cycle of over-correction is characteristic of **governor over-control** (or poor stability/too high gain) and results in hunting. **Explanation for why the other options are incorrect:** * **A) excessive speed droop:** Speed droop is an intentional characteristic where the engine speed decreases slightly as the load increases. Excessive droop causes a large, steady-state speed change between no load and full load, but it generally increases stability and dampens oscillations, thus making hunting less likely, not more likely. * **B) governor under-control:** Under-control refers to a sluggish or slow response by the governor. If the governor is under-controlled, it will take a long time to correct a speed error, but it typically will not lead to sustained, cyclical oscillations (hunting). Hunting is a symptom of aggressive or unstable control (over-control). * **C) insufficient speed droop:** While a small amount of speed droop (or isochronous operation without proper compensation) can contribute to instability, the direct cause of the sustained oscillation known as hunting is the control loop aggressively overshooting the target—which is defined as over-control. Insufficient droop sets the condition for potential instability, but **over-control** describes the specific dynamic action causing the hunting behavior.