AME 11 End of Unit – SVE Study

AME 11 End of Unit Quiz

1 / 12

How can the gain of a control system be increased or decreased?

A) Increase the gain by reducing the proportional band; decrease the gain by increasing the proportional band.

C) Increase the gain by adding derivative control; decrease the gain by removing derivative control.

D) Increase the gain by reducing the setpoint; decrease the gain by increasing the setpoint.

B) Increase the gain by increasing the integral time; decrease the gain by reducing the integral time.

2 / 12

Define the term Proportional Action.

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

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

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

3 / 12

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

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.

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.

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.

4 / 12

Explain the purpose of Integral Action.

D) Integral action maintains a constant output level regardless of the error to keep the system stable.

B) Integral action integrates the error over time to eliminate steady-state error, ensuring that the system eventually reaches the setpoint.

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

A) Integral action adjusts the control output based on the magnitude of the error, aiming to quickly correct deviations from the setpoint.

5 / 12

State with reasons, the type of actuator fitted to the process valves for a fuel supply system in which the valve must not move on loss of power to the control system.

B) Pneumatic Actuator with Spring Return: Reason: This actuator is designed to return to a default position using a spring when power is lost, which could result in undesired movement or system instability.

A) Electric Actuator with Fail-Safe Mechanism: Reason: This actuator includes a fail-safe mechanism that ensures the valve remains in its last position or moves to a predetermined safe position if there is a loss of power.

C) Hydraulic Actuator with Manual Override: Reason: While this actuator allows for manual control, it is not ideal for maintaining valve position during power loss, as it may require manual intervention to secure the valve.

D) Solenoid Actuator: Reason: This actuator is not suitable as it relies on continuous power to maintain the valve position and will fail to hold the valve in place if power is lost.

6 / 12

Explain dead zone in control terms.

B) Dead zone is the time required for a system to stabilize after a disturbance. Reason: This describes settling time rather than dead zone, which is about the unresponsive range in the input-output relationship.

A) Dead zone refers to a range within which changes in input do not produce any change in the output of a control system. Reason: This correctly describes dead zone as a region where the system is unresponsive to inputs within that range.

C) Dead zone is the amount of time it takes for the control system to start responding after a command is issued. Reason: This describes the delay or lag in response, not the concept of dead zone.

D) Dead zone is the ability of a control system to maintain output stability despite fluctuations in the input. Reason: This describes system stability rather than dead zone, which is specifically about input-output response range.

7 / 12

With reference to engine governors, explain sensitivity.

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.

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.

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.

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.

8 / 12

With reference to engine governors, explain isochronous governing.

B) Isochronous governing allows the engine speed to fluctuate slightly around the set point to accommodate load changes. Reason: This describes droop control rather than isochronous governing, where slight fluctuations are acceptable.

C) Isochronous governing adjusts the engine speed only during idle periods to maintain stability. Reason: Isochronous governing applies to all operating conditions, not just idle periods.

D) Isochronous governing is a technique where the engine speed is allowed to drift with load changes, optimizing fuel efficiency. Reason: Allowing speed drift with load changes describes a droop control system, not isochronous governing.

A) Isochronous governing ensures that the engine speed remains constant regardless of the load applied, maintaining the same speed even with varying demands. Reason: Isochronous governing is designed to keep the engine speed constant, independent of changes in load.

9 / 12

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

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

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

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.

10 / 12

What is the relationship between proportional band and gain in a control system?

D) Proportional band and gain are the same thing.

B) Proportional band is inversely proportional to gain.

C) Proportional band and gain are independent of each other.

A) Proportional band is directly proportional to gain.

11 / 12

With reference to engine governors, explain speed droop.

D) Speed droop describes the governor's ability to maintain a constant engine speed despite fluctuations in ambient temperature. Reason: Speed droop is related to load changes, not temperature fluctuations.

B) Speed droop refers to the increase in engine speed when the governor's sensitivity is reduced. Reason: Reducing sensitivity affects response time, not speed droop.

C) Speed droop is the amount by which the governor’s set point changes to match variations in fuel quality. Reason: Speed droop pertains to load variations, not fuel quality.

A) Speed droop is the reduction in engine speed that occurs when the engine is subjected to an increase in load, relative to the no-load speed. Reason: Speed droop measures how much the engine speed decreases from its no-load speed when a load is applied.

12 / 12

Explain hysteresis in control terms.

B) Hysteresis is the ability of a control system to adapt its response based on changes in input conditions. Reason: This describes adaptability rather than hysteresis, which specifically deals with lag in response due to past inputs.

C) Hysteresis is the effect of system instability caused by rapid changes in input. Reason: This describes system instability or oscillations rather than the lag or memory effect described by hysteresis.

D) Hysteresis is the speed at which a control system can respond to input changes. Reason: This describes response time rather than hysteresis, which involves differences in response based on input history.

A) Hysteresis is the phenomenon where the output of a control system depends on its past input, causing a lag or delay in response. Reason: This describes hysteresis correctly, where the system’s output is influenced by the history of inputs, leading to different responses for increasing versus decreasing inputs.

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