AME 11 End of Unit – SVE Study

AME 11 End of Unit Quiz

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With reference to engine governors, explain sensitivity.

D) Sensitivity indicates the level of noise produced by the governor during operation. Reason: Noise levels are not related to the sensitivity of a governor but rather to its design and operation characteristics.

B) Sensitivity refers to the governor’s response to small changes in the fuel supply, affecting the engine speed control. Reason: A sensitive governor will react quickly to minor adjustments in fuel input, thereby maintaining precise engine speed control.

A) Sensitivity refers to the governor's ability to maintain engine speed despite fluctuations in load conditions. Reason: A sensitive governor adjusts engine fuel input or throttle position to counteract variations in load and keep the engine speed constant.

C) Sensitivity describes how easily the governor can detect changes in ambient temperature and adjust engine speed accordingly. Reason: While temperature changes can affect engine performance, sensitivity in a governor is primarily related to its response to load changes and fuel adjustments.

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In an On-Off control system, what happens when the controlled variable exceeds the set point?

C) The system increases the output to correct the error.

B) The system switches off the output to bring the variable back to the set point.

D) The system remains inactive until the variable drops significantly.

A) The system modulates the output to gradually reduce the variable.

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Explain proportional bandwidth in control terms.

B) Proportional bandwidth is the measure of how quickly a system can respond to changes in the proportional gain setting. Reason: This describes response time rather than the range of input values for proportional action.

A) Proportional bandwidth refers to the range of input values over which the proportional control action is effective in adjusting the output of a system. Reason: This describes how the range within which proportional control can operate effectively is defined, focusing on the input values that impact the output.

D) Proportional bandwidth is the extent of variation in the system output for a given change in proportional gain. Reason: This describes the effect of changing proportional gain on output variation, rather than the range of input values affecting proportional control.

C) Proportional bandwidth refers to the frequency range over which the proportional controller can maintain a constant output. Reason: This describes frequency response rather than the range of input values within which proportional control is effective.

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Explain proportional bandwidth in control terms.

A) Proportional bandwidth refers to the range of input values for which the proportional controller provides a linear response.

D) Proportional bandwidth describes the extent to which the proportional controller can correct errors before reaching the maximum output.

B) Proportional bandwidth is the range of frequencies over which the proportional controller effectively responds to changes in the process variable.

C) Proportional bandwidth is the width of the proportional band within which the control action is active and varies linearly with the error.

5 / 12

How is the level in a water tank controlled by a float and lever proportional system?

C) The float rises with the water level, opening a valve to allow more water into the tank.

D) The lever controls the water level by switching between two fixed positions—completely open or completely closed.

A) The float rises with the water level, causing the lever to close a valve, stopping the inflow of water when the desired level is reached.

B) The float sinks as the water level rises, which directly activates a pump to remove excess water from the tank.

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With reference to hydraulic governors fitted to alternators designed to run in parallel, explain why these governors have adjustable integral action.

B) To ensure that the governor can handle variations in load and maintain stable operation by adjusting the steady-state accuracy.

A) To allow the governor to respond more quickly to sudden load changes and reduce the frequency of the alternator.

D) To prevent the governor from responding to minor fluctuations in the load, reducing wear and tear on the governor mechanism.

C) To increase the governor’s sensitivity to small changes in load, which improves the alternator’s synchronization with other units.

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2. Which of the following is a typical application of an On-Off control system?

D) Flow control in a proportional valve system.

B) Temperature control in a household thermostat.

C) Pressure regulation in a hydraulic system.

A) Speed control of a variable frequency drive.

8 / 12

Define the term Proportional Action.

D) Proportional action uses a fixed output level regardless of the error magnitude to maintain system stability.

C) Proportional action predicts future errors by adjusting the control output based on the rate of change of the error.

A) Proportional action adjusts the control output based on the magnitude of the error, where the output is directly proportional to the difference between the setpoint and the actual value.

B) Proportional action integrates the error over time to adjust the control output, aiming to eliminate steady-state error.

9 / 12

With reference to engine governors, explain stability.

D) Stability refers to the governor's ability to handle extreme variations in ambient temperature without affecting engine performance. Reason: While temperature variations can affect performance, stability specifically concerns speed consistency under load changes.

A) Stability refers to the governor's ability to maintain a constant engine speed without oscillations or fluctuations when subjected to varying loads. Reason: Stability in governors is about how consistently the engine speed is maintained despite changes in load or other disturbances.

C) Stability is the measure of how much the governor's set point can drift from the desired speed due to wear and tear. Reason: Set point drift due to wear is not directly related to stability, which focuses on maintaining speed consistency.

B) Stability describes the governor's capacity to change the engine speed quickly in response to sudden changes in fuel supply. Reason: Rapid response is more related to the governor's responsiveness, not its stability.

10 / 12

Describe using control block diagram terms how a governor maintains the speed of a diesel engine driving a generator.

B) The governor compares the actual engine speed to the desired speed setpoint and uses a proportional-integral-derivative (PID) control block to adjust the fuel input and maintain the engine speed.

D) The governor uses a feedback loop where the actual engine speed is compared to a fixed reference value, adjusting the fuel input based on a simple on-off control block.

C) The governor uses a manual control block to adjust the engine speed directly without feedback, ensuring the engine speed remains constant regardless of load changes.

A) The governor adjusts the fuel input based on the difference between the desired speed setpoint and the actual engine speed (feedback), using a proportional-only control block.

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Explain the purpose of Derivative Action.

D) Derivative Action compensates for errors in the system by applying a proportional correction based on the current error value alone.

A) Derivative Action aims to eliminate steady-state errors by continuously adjusting the control output based on the accumulated error over time.

B) Derivative Action helps to anticipate future errors by reacting to the rate of change of the error, thereby improving the system’s stability and response time.

C) Derivative Action adjusts the control output to maintain a constant error, ensuring that the system remains at a fixed setpoint without any fluctuations.

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Explain settling time in control terms.

A) Settling time is the time it takes for a system's output to initially reach its desired value after a disturbance has been applied. Reason: Settling time is concerned with the time to stabilize around the desired value, not the initial reach.

D) Settling time is the time it takes for the system to completely stop moving after a control action has been implemented. Reason: Settling time focuses on stabilization around the set point, not complete cessation of movement.

B) Settling time is the time required for the system's output to remain within a specified range around the set point after a disturbance, and it measures the time until the output stops oscillating significantly. Reason: This correctly describes settling time as the time it takes for the output to stay within a certain percentage of the set point and cease significant oscillations.

C) Settling time is the total time it takes for the system to return to its original state after a disturbance has been removed. Reason: Settling time is related to stabilization around the new set point, not returning to the original state.

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