AME 11 End of Unit – SVE Study

AME 11 End of Unit Quiz

1 / 12

Explain the purpose of Derivative Action.

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.

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

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

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

2 / 12

How does hysteresis improve the performance of an On-Off control system?

D) It enables the system to predict and correct future errors.

A) It increases the switching frequency of the system.

C) It allows the system to adjust output continuously.

B) It prevents rapid cycling by creating a dead zone between switching on and off.

3 / 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.

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.

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.

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.

4 / 12

State the reasons for fitting a pneumatic process valve with a feedback positioner.

B) A feedback positioner is fitted to increase the air pressure supplied to the actuator, which helps in enhancing the overall force applied to the valve.

C) A feedback positioner is fitted to reduce the overall power consumption of the valve actuator, improving energy efficiency.

A) A feedback positioner is fitted to monitor the valve position and provide real-time correction signals to ensure the valve remains at the desired position, improving accuracy and stability in the process control.

D) A feedback positioner is fitted to provide a backup control signal in case the primary control system fails, ensuring the valve remains operational.

5 / 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.

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.

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

6 / 12

With reference to engine governors, explain stability.

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.

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.

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.

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.

7 / 12

State with reasons, the type of actuator fitted to the process valves for a lubrication oil cooling system in which the valve diverts the oil through a cooler.

A) Electric Actuator: Reason: An electric actuator offers precise control of the valve position and can be easily integrated with control systems to modulate the oil flow through the cooler as required.

D) Manual Actuator: Reason: Manual actuators require manual intervention to adjust the valve position, which is not ideal for automatic and precise control of oil flow through a cooler.

C) Hydraulic Actuator: Reason: Hydraulic actuators are generally used for high-force applications and may be less suitable for the precise control required in diverting oil through a cooler.

B) Pneumatic Actuator: Reason: Pneumatic actuators provide reliable and fast operation and are well-suited for applications requiring frequent adjustments to the valve position, such as diverting oil flow through a cooler.

8 / 12

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

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

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.

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

9 / 12

Explain proportional bandwidth in control terms.

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

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

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

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

10 / 12

Explain settling time in control terms.

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.

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.

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.

11 / 12

Describe the effect of increasing the controller gain with respect to the steady-state tank level when the outflow is increased in a float and lever proportional system.

C) The steady-state tank level will decrease more slowly in response to the increased outflow.

D) The steady-state tank level will remain unchanged regardless of the controller gain.

B) The steady-state tank level will oscillate more and be less stable.

A) The steady-state tank level will become more stable and closer to the setpoint.

12 / 12

What is a potential drawback of using an On-Off control system?

A) It requires complex programming to function.

D) It consumes more energy than other types of control systems.

B) It is unable to achieve precise control, leading to oscillations around the set point.

C) It is more expensive than proportional control systems.

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