AME Unit 11 PID, Engine Governors, Control Terms Quiz

Copy - AME Q11

1 / 37

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

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.

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

2 / 37

What is the primary characteristic of a Discontinuous (On-Off) control system?

A) The output is continuously variable.

B) The output is either fully on or fully off, with no intermediate states.

C) The system adjusts output in small increments.

D) The system provides proportional control based on the error magnitude.

3 / 37

Explain settling time in control terms.

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.

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.

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.

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

B) Temperature control in a household thermostat.

D) Flow control in a proportional valve system.

C) Pressure regulation in a hydraulic system.

A) Speed control of a variable frequency drive.

5 / 37

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.

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.

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.

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

A) Proportional band is directly proportional to gain.

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

B) Proportional band is inversely proportional to gain.

D) Proportional band and gain are the same thing.

7 / 37

With reference to engine governors, explain speed droop.

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.

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.

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.

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.

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

C) It allows the system to adjust output continuously.

A) It increases the switching frequency of the system.

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

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

9 / 37

What happens when the flow out is increased in a system where the water tank level is controlled by a float and lever proportional system?

D) The float drops, causing the control valve to open more to increase the inflow.

C) The float rises, causing the control valve to close, reducing the inflow.

A) The float rises, causing the control valve to open more to increase the inflow.

B) The float drops, causing the control valve to close, reducing the inflow.

10 / 37

Describe the effect of excessive Derivative Action.

C) Excessive Derivative Action can result in a system that quickly reaches the setpoint without overshooting or oscillating.

A) Excessive Derivative Action can lead to a sluggish response time and an increase in steady-state errors.

D) Excessive Derivative Action can decrease the system’s overall response time and improve its accuracy in maintaining the setpoint.

B) Excessive Derivative Action can cause the system to become overly sensitive to noise, leading to oscillations and instability.

11 / 37

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.

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.

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.

12 / 37

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.

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.

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

13 / 37

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

A) It requires complex programming to function.

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

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

C) It is more expensive than proportional control systems.

14 / 37

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.

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.

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.

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Explain integral action in control terms.

B) Integral action describes the process of adjusting the control output proportionally to the rate of change of the error.

D) Integral action refers to the system’s ability to anticipate future errors based on the current rate of change in the process variable.

C) Integral action is the component of the control system that responds to changes in the process variable by varying the gain of the proportional controller.

A) Integral action refers to the ability of a control system to eliminate steady-state error by continuously adjusting the control output based on the accumulated error over time.

16 / 37

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

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

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

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.

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.

17 / 37

Explain the purpose of Integral Action.

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

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.

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

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Describe a possible effect of excessive Integral Action.

B) Excessive Integral Action can cause the system to oscillate or exhibit sustained oscillations around the setpoint due to an overcompensation of errors.

A) Excessive Integral Action can lead to a quick and accurate response to setpoint changes, reducing the time required to reach the target value.

C) Excessive Integral Action can make the control system unresponsive to errors, resulting in a steady and stable system performance.

D) Excessive Integral Action can increase the system’s ability to predict future errors accurately, leading to improved overall system stability.

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Explain dead zone in control terms.

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.

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.

20 / 37

With reference to hydraulic governors fitted to alternators designed to run in parallel, explain how two generators operating in parallel are able to achieve a stable load share with a 50/50 ratio.

A) By adjusting the governor settings to ensure each generator automatically compensates for any load imbalances and shares the load equally.

B) By using manual load distribution switches to physically adjust the load shared by each generator to achieve a 50/50 ratio.

C) By synchronizing the generators' speed and voltage settings, and using governors with equal proportional and integral action to balance the load distribution.

D) By connecting each generator to separate load banks and using separate governors to adjust the load independently, thus ensuring a 50/50 ratio.

21 / 37

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.

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.

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.

22 / 37

State the reasons for fitting a pneumatic process valve with a volume booster.

B) A volume booster is fitted to reduce the air pressure supplied to the actuator, which helps in minimizing the force required to operate the valve.

A) A volume booster is fitted to increase the flow rate of air to the actuator, enabling faster valve movement and reducing the time required to achieve the desired valve position.

C) A volume booster is fitted to decrease the overall air consumption of the valve, thereby improving energy efficiency in the pneumatic system.

D) A volume booster is fitted to provide redundant control signals to the actuator, ensuring higher reliability in case of signal loss.

23 / 37

With reference to engine governors, explain hunting.

A) Hunting is the term used to describe a governor's inability to maintain a constant engine speed due to excessive fluctuation in engine speed around a set point. Reason: Hunting occurs when the governor repeatedly overshoots and undershoots the target speed, causing erratic engine performance.

D) Hunting is the term used for a governor’s ability to remain unaffected by variations in fuel quality. Reason: Fuel quality variations impact engine performance but are not described as hunting.

C) Hunting describes the process of adjusting the governor's sensitivity to improve engine speed stability. Reason: Adjusting sensitivity is related to tuning, not hunting, which involves excessive fluctuation in engine speed.

B) Hunting refers to the governor’s ability to detect and compensate for sudden changes in load quickly. Reason: Quick load compensation is not referred to as hunting but rather as a desirable feature in governors.

24 / 37

Explain repeatability in control terms.

A) Repeatability refers to the ability of a control system to return to the exact same output every time a specific input is applied, assuming no changes in system conditions. Reason: This accurately describes repeatability as the system's ability to consistently produce the same output for the same input under unchanged conditions.

B) Repeatability is the time it takes for a system to return to its original state after a disturbance has been removed. Reason: This describes settling time rather than repeatability, which is about consistency in output rather than recovery time.

D) Repeatability is the extent to which a control system can minimize oscillations in its output. Reason: This describes the concept of damping or stability, not repeatability.

C) Repeatability measures the ability of a system to maintain a stable output despite variations in input signals. Reason: This describes system stability, not repeatability. Repeatability focuses on consistency of output for the same input.

25 / 37

Explain derivative action in control terms.

A) Derivative action involves adjusting the control output based on the rate of change of the error, aiming to predict future errors and reduce overshoot.

C) Derivative action adjusts the control output based on the proportional deviation from the setpoint, with no regard to the rate of change.

D) Derivative action is the component of the control system that maintains the steady-state error by constantly adjusting the control output proportionally.

B) Derivative action describes the process of integrating the accumulated error over time to adjust the control output.

26 / 37

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.

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

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

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

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

27 / 37

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.

28 / 37

With reference to engine governors, explain isochronous governing.

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.

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.

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.

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.

29 / 37

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

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.

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

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

30 / 37

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.

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.

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.

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.

31 / 37

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

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

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

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

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

32 / 37

Explain hysteresis in control terms.

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.

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.

33 / 37

Describe the reasons for integrating the error signal and the effect it has on the governor fuel rack.

A) Integrating the error signal helps in eliminating steady-state error by providing continuous correction over time, leading to a gradual adjustment of the governor fuel rack to maintain the desired engine speed.

D) Integrating the error signal helps in stabilizing the system by making the governor fuel rack adjustments slower, which prevents any rapid changes and ensures the engine speed remains constant.

B) Integrating the error signal helps in amplifying transient responses by applying a large correction immediately, causing abrupt changes to the governor fuel rack and quickly adjusting the engine speed.

C) Integrating the error signal helps in reducing the proportional gain needed for control, which simplifies the control system and makes the governor fuel rack less responsive to changes in engine speed.

34 / 37

Explain the purpose of Derivative Action.

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.

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

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.

35 / 37

Describe integral action in a control system.

B) Integral action increases the control output to eliminate steady-state error over time by integrating the error signal.

A) Integral action adjusts the control output based on the rate of change of the error signal.

D) Integral action adjusts the control output to match the process variable to the setpoint instantly.

C) Integral action maintains a constant control output regardless of changes in the error signal.

36 / 37

Explain proportional bandwidth in control terms.

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

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

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.

37 / 37

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.

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