Question 38 3AE02 - Third Assistant Engineer (Alt)

The Correct Answer is D. **Why Option D ("Deadband") is Correct:** The term **Deadband** (or "dead time" or "hysteresis") in a control system refers to the range of input values within which no action or response is taken by the controller or governor. In the context of a speed control governor, the Deadband is the total magnitude of the speed change (deviation from the set point, both up and down) that must occur before the governor mechanism overcomes internal friction and clearances and initiates movement of the fuel control linkage (corrective action). It represents the insensitivity of the governor mechanism, defining the minimum speed change required to start regulation as the load changes. **Why the Other Options are Incorrect:** * **A) Power:** Power refers to the rate at which work is done (e.g., the output of the engine or the capability of the governor actuator). While power is crucial for the engine's operation, it does not define the magnitude of speed change required to trigger corrective action. * **B) Sensitivity:** Sensitivity (often related to "droop" or "speed regulation") describes the change in governor output (fuel linkage movement) relative to the change in input (speed). A highly sensitive governor responds quickly and significantly to small speed changes, but the term "Deadband" specifically defines the *lack* of response over a small initial range of speed change due to mechanical constraints. * **C) Promptness:** Promptness is a qualitative term referring to the speed or quickness of the governor's overall reaction time once it starts moving. It relates to the dynamic response characteristics (how quickly it settles the speed) but does not define the initial range of speed change that occurs *before* any action is initiated.