Aux 2 Unit 7 Load sharing Quiz

Aux 2 Unit 7 Q1

1 / 7

If the excitation of one generator in a parallel system decreases, how does this affect the load sharing between the generators?

B) The generator with reduced excitation supplies less reactive power, and the other generator compensates

A) The generator with reduced excitation takes on more real power

D) The load remains constant without any change in reactive power distribution

C) Both generators supply equal reactive power despite excitation changes

Correct Answer:
B) The generator with reduced excitation supplies less reactive power, and the other generator compensates

Explanation:
When the excitation of one generator is reduced, it supplies less reactive power, which leads to the other generator compensating by supplying more reactive power to maintain system stability.

Correct Answer:
B) The generator with reduced excitation supplies less reactive power, and the other generator compensates

2 / 7

What can be the effect on the mechanical parts of the generators if they are connected out of phase?

D) The mechanical torque will decrease steadily

B) The generators will run more efficiently

C) High mechanical stress and potential damage to the rotor and shaft

A) There will be no effect

Correct Answer:
C) High mechanical stress and potential damage to the rotor and shaft

Explanation:
Connecting generators out of phase can cause mechanical shock due to sudden torque changes, potentially damaging the rotors, shafts, or other mechanical components.

Correct Answer:
C) High mechanical stress and potential damage to the rotor and shaft

Explanation:
Connecting generators out of phase can cause mechanical shock due to sudden torque changes, potentially damaging the rotors, shafts, or other mechanical components.

3 / 7

What electrical phenomenon can occur if the main circuit breaker is closed while the generators are out of phase?

B) The generation of a high inrush current

C) An immediate reduction in voltage

A) A gradual increase in frequency

D) A drop in system power factor

Correct Answer:
B) The generation of a high inrush current

Explanation:
Closing the circuit breaker while the generators are out of phase can create a significant inrush current as the system attempts to correct the phase difference, potentially causing damage or tripping the protective devices.

Correct Answer:
B) The generation of a high inrush current

4 / 7

What happens to the reactive power output of one generator if its excitation is reduced while the load on the system remains constant?

A) The reactive power output increases

C) The true power output increases

D) The generator stops supplying power entirely

B) The generator’s reactive power output decreases

Correct Answer:
B) The generator’s reactive power output decreases

Explanation:
Reducing the excitation of a generator decreases its reactive power output because the reduced field current weakens the magnetic field, affecting the ability to supply reactive power.

Correct Answer:
B) The generator’s reactive power output decreases

5 / 7

Why is it critical to ensure that the phases of two generators are in phase before closing the main circuit breaker?

D) To increase the frequency of both generators

A) To prevent excessive reactive power generation

C) To synchronize voltage magnitudes only

B) To avoid mechanical torque shock and electrical surges

Correct Answer:
B) To avoid mechanical torque shock and electrical surges

Explanation:
If the phases are not aligned when the circuit breaker is closed, the resulting phase mismatch can cause mechanical torque shock and electrical surges that may damage the generators or associated equipment.

Correct Answer:
B) To avoid mechanical torque shock and electrical surges

6 / 7

What is a potential effect on the system if one generator’s excitation is reduced significantly while operating in parallel?

D) The generator with reduced excitation stops generating true power

A) The voltage of the system increases

C) The overall system voltage may decrease

B) The power factor of the generator with reduced excitation becomes more lagging

Correct Answer:
C) The overall system voltage may decrease

Explanation:
Reducing the excitation of one generator can lead to a decrease in the system’s overall voltage because there is less reactive power being supplied to support the voltage.

Correct Answer:
C) The overall system voltage may decrease

Explanation:
Reducing the excitation of one generator can lead to a decrease in the system’s overall voltage because there is less reactive power being supplied to support the voltage.

7 / 7

What is the potential consequence of closing the main circuit breaker when the frequency and voltage are equal, but the phases are out of phase?

B) The generators may trip due to a phase mismatch

C) The load is distributed equally without any problems

A) The generators synchronize without issue

D) The reactive power output immediately stabilizes

Correct Answer:
B) The generators may trip due to a phase mismatch

Explanation:
Closing the circuit breaker when the generators are out of phase can cause a significant phase angle difference, resulting in a large surge of current that can trip protection systems or damage the generators.

Correct Answer:
B) The generators may trip due to a phase mismatch

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Aux 2 Unit 7 Q2

1 / 6

What can occur if generators with different speed droop settings are running in parallel and the load suddenly increases?

B) The generator with the lower droop may become overloaded

C) Both generators will stop supplying power

D) The system will maintain frequency stability without any adjustment

A) The load will be shared equally without any issues

Correct Answer:
B) The generator with the lower droop may become overloaded

Explanation:
When the load increases suddenly, the generator with the lower droop setting may respond more aggressively by increasing its power output more rapidly than the one with the higher droop, potentially leading to an overload.

Correct Answer:
B) The generator with the lower droop may become overloaded

2 / 6

What effect would unequal droop settings have on frequency when generators are sharing an increasing load?

D) The generators would shut down due to load mismatch

C) Both generators would run at a higher frequency

B) The generator with the higher droop setting would drop more in speed, causing a frequency imbalance

A) The frequency would remain constant

Correct Answer:
B) The generator with the higher droop setting would drop more in speed, causing a frequency imbalance

Explanation:
With unequal droop settings, the generator with the higher droop reduces speed more when the load increases, which can lead to a frequency imbalance if not managed properly.

Correct Answer:
B) The generator with the higher droop setting would drop more in speed, causing a frequency imbalance

Explanation:
With unequal droop settings, the generator with the higher droop reduces speed more when the load increases, which can lead to a frequency imbalance if not managed properly.

3 / 6

What is the term "speed droop" in relation to an AC generator?

B) The total decrease in voltage under load conditions

C) The increase in speed as the load increases

A) The difference between the no-load and full-load speed of a generator

D) The reduction in power output due to temperature changes

Correct Answer:
A) The difference between the no-load and full-load speed of a generator

Explanation:
Speed droop refers to the percentage decrease in the speed of a generator as it goes from no-load to full-load conditions. This characteristic helps in load sharing when generators are connected in parallel.

Correct Answer:
A) The difference between the no-load and full-load speed of a generator

4 / 6

Why is speed droop important in the operation of AC generators in parallel?

C) To reduce the fuel consumption of the generator

A) To increase the frequency of the generator output

B) To allow generators to share load proportionally

D) To stabilize voltage under varying loads

Correct Answer:
B) To allow generators to share load proportionally

Explanation:
Speed droop enables generators to adjust their power output relative to their load, facilitating proportional load sharing when operating in parallel.

Correct Answer:
B) To allow generators to share load proportionally

Explanation:
Speed droop enables generators to adjust their power output relative to their load, facilitating proportional load sharing when operating in parallel.

5 / 6

How does speed droop help maintain load sharing stability between parallel generators?

C) It synchronizes the phases of the generators

B) It allows each generator to adjust its power output proportionally based on its droop setting

A) It decreases the voltage of the system to balance the load

D) It automatically increases the frequency of both generators

Correct Answer:
B) It allows each generator to adjust its power output proportionally based on its droop setting

Explanation:
Speed droop enables each generator to proportionally adjust its power output as the load changes, maintaining stability and balanced load sharing in parallel operation.

Correct Answer:
B) It allows each generator to adjust its power output proportionally based on its droop setting

Explanation:
Speed droop enables each generator to proportionally adjust its power output as the load changes, maintaining stability and balanced load sharing in parallel operation.

6 / 6

What happens when two generators with different speed droop settings are running in parallel and are sharing the load equally?

C) The generator with the higher droop setting will naturally take on more of the load

A) The generator with the lower droop will carry a smaller portion of the load

D) The generators will have equal output with no adjustments needed

B) Both generators will maintain the same power output regardless of their droop settings

Correct Answer:
C) The generator with the higher droop setting will naturally take on more of the load

Explanation:
When generators have different droop settings, the one with the higher droop will reduce its speed more as the load increases, resulting in it taking on a larger share of the load during parallel operation.

Correct Answer:
C) The generator with the higher droop setting will naturally take on more of the load

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Aux 2 Unit 7 Q3

1 / 7

What is a potential risk if one generator’s AVR fails to provide sufficient output while running in parallel?

B) The power factor will remain unaffected

A) The generator with the faulty AVR will operate at a higher efficiency

C) The overall system voltage may fluctuate, leading to potential instability

D) The system frequency will automatically increase

Correct Answer:
C) The overall system voltage may fluctuate, leading to potential instability

Explanation:
A generator with insufficient AVR output can cause voltage instability in the power system, which can affect load-sharing stability and the overall performance of connected generators.

Correct Answer:
C) The overall system voltage may fluctuate, leading to potential instability

2 / 7

Why is it essential for an AVR to maintain a stable voltage output?

C) To protect connected electrical equipment and ensure stable power delivery

D) To reduce the generator's reactive power

A) To ensure the generator runs at maximum speed

B) To prevent overloading the prime mover

Correct Answer:
C) To protect connected electrical equipment and ensure stable power delivery

Explanation:
Stable voltage output is critical for preventing damage to connected equipment and maintaining reliable power delivery during varying load conditions.

Correct Answer:
C) To protect connected electrical equipment and ensure stable power delivery

Explanation:
Stable voltage output is critical for preventing damage to connected equipment and maintaining reliable power delivery during varying load conditions.

3 / 7

What is the primary purpose of an Automatic Voltage Regulator (AVR) in an AC generator?

A) To adjust the generator’s frequency

B) To regulate the generator’s voltage output

D) To increase the generator's power factor

C) To control the speed of the generator

Correct Answer:
B) To regulate the generator’s voltage output

Explanation:
An AVR automatically adjusts the excitation current to the generator's field winding, maintaining a consistent output voltage despite load variations.

Correct Answer:
B) To regulate the generator’s voltage output

Explanation:
An AVR automatically adjusts the excitation current to the generator's field winding, maintaining a consistent output voltage despite load variations.

4 / 7

What would be the immediate effect if one generator’s AVR gives a low output while running in parallel with a second generator whose AVR is functioning correctly?

C) The generator with the faulty AVR will take on more load

D) The generator with the faulty AVR will increase its output voltage

A) Both generators will share the load equally

B) The generator with the faulty AVR will supply less reactive power

Correct Answer:
B) The generator with the faulty AVR will supply less reactive power

Explanation:
In parallel operation, a generator with low AVR output will supply less reactive power, which can lead to an imbalance in reactive load sharing between the generators.

Correct Answer:
B) The generator with the faulty AVR will supply less reactive power

Explanation:
In parallel operation, a generator with low AVR output will supply less reactive power, which can lead to an imbalance in reactive load sharing between the generators.

5 / 7

What impact could a low output from an AVR have on connected equipment when a generator is running on its own?

D) The equipment's power factor will improve

A) The connected equipment operates normally

B) The equipment may overheat due to higher voltage

C) The equipment may underperform or malfunction due to low voltage

Correct Answer:
C) The equipment may underperform or malfunction due to low voltage

Explanation:
Low voltage output can cause connected equipment to operate below its optimal performance, leading to potential malfunctions or inefficiency.

Correct Answer:
C) The equipment may underperform or malfunction due to low voltage

Explanation:
Low voltage output can cause connected equipment to operate below its optimal performance, leading to potential malfunctions or inefficiency.

6 / 7

What would be the observed effect if an AVR gives a low output when a generator is running independently?

B) The generator’s output voltage will drop

C) The generator will produce more reactive power

A) The generator will increase its speed

D) The frequency of the generator will increase

Correct Answer:
B) The generator’s output voltage will drop

Explanation:
If the AVR provides a low output, the excitation current to the field windings is reduced, resulting in a lower magnetic field strength and a drop in output voltage.

Correct Answer:
B) The generator’s output voltage will drop

Explanation:
If the AVR provides a low output, the excitation current to the field windings is reduced, resulting in a lower magnetic field strength and a drop in output voltage.

7 / 7

How does a generator with a low AVR output affect the other generator when running in parallel?

C) Both generators will stop functioning

D) The frequency of both generators will drop

B) The other generator will compensate by supplying more reactive power

A) The other generator will reduce its real power output

Correct Answer:
B) The other generator will compensate by supplying more reactive power

Explanation:
The generator with the functioning AVR will adjust to supply more reactive power to maintain system voltage, balancing the total reactive load of the system.

Correct Answer:
B) The other generator will compensate by supplying more reactive power

Explanation:
The generator with the functioning AVR will adjust to supply more reactive power to maintain system voltage, balancing the total reactive load of the system.

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Aux 2 Unit 7 Q4

1 / 8

Which of the following is a primary component of a diesel generator's electronic governor?

B) Speed sensor

C) Hydraulic actuator

A) Voltage regulator

D) Cooling fan

Correct Answer:
B) Speed sensor

Explanation:
The speed sensor is a crucial component of an electronic governor that detects the generator's speed and provides feedback to the control system for adjustments.

Correct Answer:
B) Speed sensor

Explanation:
The speed sensor is a crucial component of an electronic governor that detects the generator's speed and provides feedback to the control system for adjustments.

2 / 8

What happens when the electronic governor detects an increase in load on the generator?

C) The generator voltage automatically increases

A) The actuator reduces fuel supply to slow down the engine

D) The control unit turns off the generator

B) The governor increases fuel supply to maintain speed

Correct Answer:
B) The governor increases fuel supply to maintain speed

Explanation:
When an increase in load is detected, the governor compensates by increasing the fuel supply, which helps maintain the generator’s speed and power output.

Correct Answer:
B) The governor increases fuel supply to maintain speed

Explanation:
When an increase in load is detected, the governor compensates by increasing the fuel supply, which helps maintain the generator’s speed and power output.

3 / 8

What component in an electronic governor receives feedback from the speed sensor to adjust the fuel supply?

A) Exciter

D) Rotor assembly

C) Load bank

B) Control unit

Correct Answer:
B) Control unit

Explanation:
The control unit processes the feedback from the speed sensor and adjusts the fuel supply to maintain or correct the generator's speed according to the load demand.

Correct Answer:
B) Control unit

Explanation:
The control unit processes the feedback from the speed sensor and adjusts the fuel supply to maintain or correct the generator's speed according to the load demand.

4 / 8

Which part of the electronic governor is responsible for making physical adjustments to the fuel supply in a diesel generator?

B) Actuator

D) Inverter

C) Voltage amplifier

A) Power transducer

Correct Answer:
B) Actuator

Explanation:
The actuator receives commands from the control unit and physically adjusts the fuel supply to the engine, altering its speed and output power to match the load.

Correct Answer:
B) Actuator

Explanation:
The actuator receives commands from the control unit and physically adjusts the fuel supply to the engine, altering its speed and output power to match the load.

5 / 8

Why is load sensing important in the operation of an electronic governor for a diesel generator?

C) It enables the governor to adjust fuel supply and maintain speed under changing load conditions

A) It ensures that the generator remains off until manually started

D) It changes the voltage output of the generator

B) It helps adjust the cooling system

Correct Answer:
C) It enables the governor to adjust fuel supply and maintain speed under changing load conditions

Explanation:
Load sensing allows the governor to monitor the power demand on the generator and adjust the fuel supply accordingly, ensuring stable operation and consistent output.

Correct Answer:
C) It enables the governor to adjust fuel supply and maintain speed under changing load conditions

Explanation:
Load sensing allows the governor to monitor the power demand on the generator and adjust the fuel supply accordingly, ensuring stable operation and consistent output.

6 / 8

What happens if the speed sensor in an electronic governor fails?

C) The governor may not be able to properly adjust fuel, causing potential speed fluctuations or shutdowns

B) The actuator increases fuel supply uncontrollably

A) The generator continues to run at the correct speed without adjustment

D) The voltage output of the generator increases

Correct Answer:
C) The governor may not be able to properly adjust fuel, causing potential speed fluctuations or shutdowns

Explanation:
If the speed sensor fails, the governor loses feedback, potentially leading to speed control issues and unstable generator operation.

Correct Answer:
C) The governor may not be able to properly adjust fuel, causing potential speed fluctuations or shutdowns

Explanation:
If the speed sensor fails, the governor loses feedback, potentially leading to speed control issues and unstable generator operation.

7 / 8

What is the primary purpose of the electronic governor in a diesel generator?

B) To adjust fuel supply to maintain desired engine speed and load balance

A) To regulate voltage output

D) To control the lubrication system

C) To increase the power factor of the generator

Correct Answer:
B) To adjust fuel supply to maintain desired engine speed and load balance

Explanation:
The electronic governor ensures that the generator maintains a steady speed and load balance by adjusting the fuel supply as needed.

Correct Answer:
B) To adjust fuel supply to maintain desired engine speed and load balance

Explanation:
The electronic governor ensures that the generator maintains a steady speed and load balance by adjusting the fuel supply as needed.

8 / 8

How does an electronic governor maintain the speed of a diesel generator?

C) By altering the fuel supply based on feedback from the speed sensor

A) By adjusting the generator's voltage output

D) By changing the generator’s physical configuration

B) By controlling the frequency of the generator

Correct Answer:
C) By altering the fuel supply based on feedback from the speed sensor

Explanation:
The electronic governor uses feedback from the speed sensor to adjust the fuel supply, ensuring the generator runs at the correct speed regardless of load changes.

Correct Answer:
C) By altering the fuel supply based on feedback from the speed sensor

Explanation:
The electronic governor uses feedback from the speed sensor to adjust the fuel supply, ensuring the generator runs at the correct speed regardless of load changes.

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