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Electrical Principles for the Electrical Trades Volume 2 Jim Jenneson 6e - Test Bank

Electrical Principles for the Electrical Trades Volume 2 Jim Jenneson 6e - Test Bank   Instant Download - Complete Test Bank With Answers     Sample Questions Are Posted Below   Chapter 07 Student: ___________________________________________________________________________ 1. What is the name given to an electrical machine that is designed to operate at the same speed as …

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Electrical Principles for the Electrical Trades Volume 2 Jim Jenneson 6e – Test Bank

 

Instant Download – Complete Test Bank With Answers

 

 

Sample Questions Are Posted Below

 

Chapter 07

Student: ___________________________________________________________________________

1. What is the name given to an electrical machine that is designed to operate at the same speed as the rotating magnetic field?

A. a split phase machine

 

B. an induction motor

 

C. a synchronous machine

 

D. a synchronised motor

 

2. What are the typical connections for a large alternator?

A. three phase to the rotor and three phase to the stator

 

B. DC to the rotor and three phase to the stator

 

C. three phase to the rotor and DC to the stator

 

D. single phase to the rotor and three phase to the stator

 

3. Which of the following prime movers would be the most suitable for an alternator with a salient pole rotor?

A. hydroelectric turbine

 

B. steam turbine

 

C. gas turbine

 

D. petrol engine

 

4. Which of the following prime movers would be the most suitable for an alternator with a cylindrical rotor?

A. hydroelectric turbine

 

B. steam turbine

 

C. wind turbine

 

D. diesel engine

 

5. At what speed would the governor of an eight-pole diesel driven alternator have to be set to enable a frequency of 60 Hz to be generated?

A. 750 rpm

 

B. 900 rpm

 

C. 1500 rpm

 

D. 1800 rpm

 

6. What is the full load voltage for an alternator that has a voltage regulation of 3% and a no-load voltage of 23 kV?

A. 690 V

 

B. 22 310 V

 

C. 22 330 V

 

D. 23 000 V

 

7. Which of the following is not a basic factor upon which alternators are rated?

A. power factor

 

B. frequency

 

C. voltage

 

D. current

 

8. Which of the following is an advantage of using a rotating field for larger alternators?

A. extra winding space for the DC windings

 

B. easier to insulate for lower stator voltages

 

C. lower current in the rotating windings

 

D. low current windings are solidly connected

 

9. Which of the following would not be included in an equivalent circuit for a three-phase alternator?

A. a resistor

 

B. a source of AC

 

C. an inductor

 

D. a capacitor

 

10. An increase in which of the following types of loads will cause the output voltage to increase?

A. lagging power factor

 

B. unity power factor

 

C. leading power factor

 

D. DC excitation

 

11. What is the line voltage for a 50 Hz, star-connected alternator with the following details:
flux = 500 mWb/pole; kd = 0.86; kp = 0.97; 45 turns per phase.

A. 83.34 V

 

B. 144.35 V

 

C. 4167 V

 

D. 7217 V

 

12. An increase in which of the following types of loads will cause the rotor field to weaken?

A. lagging power factor

 

B. unity power factor

 

C. leading power factor

 

D. DC excitation

 

13. What is the name of the process that is required before alternators are connected in parallel?

A. synchronicity

 

B. synchronisation

 

C. syncopation

 

D. sequencing

 

14. Which of the following methods is the most accurate for ensuring that the voltages of parallel connected alternators are in phase?

A. three dark lamps method

 

B. two bright one dark method

 

C. one bright two dark method

 

D. synchroscope

 

15. When the ‘three dark’ method is used, what does the rate of lamp flicker indicate?

A. supply frequency

 

B. difference in frequencies

 

C. supply voltage

 

D. difference in voltages

 

16. Which of the following will occur if the load on a single alternator increases?

A. The governor will open to increase the input power.

 

B. The governor will close to increase the input power.

 

C. The governor will open to decrease the input power.

 

D. The governor will close to decrease the input power.

 

17. Which of the following will occur if the load on a single alternator increases?

A. The voltage regulator will increase the field current to increase the output voltage.

 

B. The voltage regulator will decrease the field current to increase the output voltage.

 

C. The voltage regulator will increase the field current to maintain the output voltage.

 

D. The voltage regulator will decrease the field current to decrease the output voltage.

 

18. What is the main purpose of amortisseur windings in an alternator?

A. to reduce armature reaction

 

B. to reduce eddy current losses

 

C. to reduce hunting

 

D. to increase starting torque

 

19. Which of the following conditions can not be adjusted by the operator so that alternators can be connected in parallel?

A. the alternator and supply voltages

 

B. the alternator and supply phase relationship

 

C. the alternator and supply frequencies

 

D. the alternator and supply phase sequences

 

20. What action will increase the load taken by an alternator when it is operating in parallel with one other alternator?

A. Decrease its governor’s set point and increase the other alternator’s set point.

 

B. Increase its governor’s set point and decrease the other alternator’s set point.

 

C. Increase its governor’s set point and increase the other alternator’s set point.

 

D. Decrease its governor’s set point and decrease the other alternator’s set point.

 

21. What is the energy source for a UPS when it is supplying current to a load?

A. battery bank

 

B. engine driven alternator

 

C. mains supply

 

D. inverter

 

22. Which of the following is not usually a prime factor in selecting an engine driven alternator?

A. availability of fuel

 

B. load power factor

 

C. alternator capacity

 

D. starting method

 

23. Which type of standby power supply would be most suitable for maintaining supply to a computer system in an office environment?

A. diesel engine driven alternator

 

B. unlimited power supply

 

C. surge protection device

 

D. uninterruptible power supply

 

24. What factor directly controls the voltage output of an engine driven alternator when it is operating?

A. the engine governor set point

 

B. the supply frequency

 

C. the number of turns per phase

 

D. the field excitation

 

25. What is the rotor speed of a rotating four-pole synchronous motor that is connected to a 50 Hz supply?

A. 1500 rpm

 

B. 1440 rpm

 

C. 0 rpm

 

D. It depends on the percentage slip.

 

26. What is the basic operating principle for a synchronous motor?

A. Lenz’s law

 

B. electromagnetic induction

 

C. magnetic attraction between opposite poles

 

D. Ohm’s law

 

27. What is the name given to the positional difference between the rotor and the stator field of a synchronous motor?

A. slip

 

B. torque angle

 

C. phase angle

 

D. armature reaction

 

28. What is the effect of a change in the load on a synchronous motor with fixed excitation?

A. An increase in the load causes a decrease in the line current.

 

B. A decrease in the load causes an increase in the line current.

 

C. An increase in the load causes a decrease in the power factor.

 

D. An increase in the load causes an increase in the power factor.

 

29. What is the effect of a change in the field excitation of a synchronous motor with a constant load?

A. An increase in the field excitation causes a decrease in the line current at a lagging power factor.

 

B. An increase in the field excitation causes an increase in the line current at a lagging power factor.

 

C. An increase in the field excitation causes an increase in the line current at a leading power factor.

 

D. An increase in the field excitation causes a decrease in the line current at a leading power factor.

 

30. What is a synchronous capacitor?

A. an over-excited synchronous motor

 

B. an over-excited alternator

 

C. an under-excited synchronous motor

 

D. a synchronous motor operating at unity power factor

 

31. What is the purpose of an auxiliary motor?

A. It is a prime mover for an alternator.

 

B. It provides the field excitation for a synchronous machine.

 

C. It provides feedback to an automatic voltage regulator.

 

D. It brings a synchronous motor up to speed.

 

32. Which of the following is not a typical application for synchronous motors?

A. voltage control for transmission lines

 

B. power factor correction

 

C. air conditioner compressors

 

D. rock and ore crushing heads

 

33. When a synchronous machine is started as an induction motor, which of the following occurs?

A. The slip ring connections are open-circuited.

 

B. The stator voltage is increased.

 

C. The rotor field and stator field lock together.

 

D. The amortisseur windings act as a squirrel cage.

 

34. What effect does increasing the field excitation from a low value to a high value have on a synchronous motor that is operating on a constant load?

A. The torque will increase to a maximum and then decrease.

 

B. The power factor will increase to a maximum and then decrease.

 

C. The stator current will increase to a maximum and then decrease.

 

D. The rotor current will increase to a maximum and then decrease.

 

35. Which of the following is a single-phase synchronous motor?

A. reticence motor

 

B. reluctance motor

 

C. hysterics motor

 

D. shaded-pole motor

 

36. What is the primary application for single-phase synchronous motors?

A. constant speed applications

 

B. high speed applications

 

C. constant torque applications

 

D. high torque applications

 

37. What causes the rotor of a reluctance motor to continue rotating when the stator flux is low?

A. interference

 

B. induction

 

C. impetus

 

D. inertia

 

38. What is a typical method for starting a reluctance motor?

A. use an auxiliary motor

 

B. start as an induction motor

 

C. start as a shaded pole motor

 

D. use a different number of rotor poles compared to stator poles

 

39. What is a typical method for starting a hysteresis motor?

A. use an auxiliary motor

 

B. start as an induction motor

 

C. start as a shaded-pole motor

 

D. use a different number of rotor poles compared to stator poles.

 

40. What is the benefit of a 400 Hz single-phase synchronous machine compared to one designed for 50 Hz?

A. It will deliver twice the power for the same physical size.

 

B. It will be 64 times smaller for the same output.

 

C. It will operate at a lower speed for the same number of poles.

 

D. There is no additional benefit.

 

 

 

Chapter 07 Key

1. What is the name given to an electrical machine that is designed to operate at the same speed as the rotating magnetic field?

A. a split phase machine

 

B. an induction motor

 

C. a synchronous machine

 

D. a synchronised motor

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

2. What are the typical connections for a large alternator?

A. three phase to the rotor and three phase to the stator

 

B. DC to the rotor and three phase to the stator

 

C. three phase to the rotor and DC to the stator

 

D. single phase to the rotor and three phase to the stator

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

3. Which of the following prime movers would be the most suitable for an alternator with a salient pole rotor?

A. hydroelectric turbine

 

B. steam turbine

 

C. gas turbine

 

D. petrol engine

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

4. Which of the following prime movers would be the most suitable for an alternator with a cylindrical rotor?

A. hydroelectric turbine

 

B. steam turbine

 

C. wind turbine

 

D. diesel engine

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

5. At what speed would the governor of an eight-pole diesel driven alternator have to be set to enable a frequency of 60 Hz to be generated?

A. 750 rpm

 

B. 900 rpm

 

C. 1500 rpm

 

D. 1800 rpm

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

6. What is the full load voltage for an alternator that has a voltage regulation of 3% and a no-load voltage of 23 kV?

A. 690 V

 

B. 22 310 V

 

C. 22 330 V

 

D. 23 000 V

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

7. Which of the following is not a basic factor upon which alternators are rated?

A. power factor

 

B. frequency

 

C. voltage

 

D. current

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

8. Which of the following is an advantage of using a rotating field for larger alternators?

A. extra winding space for the DC windings

 

B. easier to insulate for lower stator voltages

 

C. lower current in the rotating windings

 

D. low current windings are solidly connected

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

9. Which of the following would not be included in an equivalent circuit for a three-phase alternator?

A. a resistor

 

B. a source of AC

 

C. an inductor

 

D. a capacitor

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

10. An increase in which of the following types of loads will cause the output voltage to increase?

A. lagging power factor

 

B. unity power factor

 

C. leading power factor

 

D. DC excitation

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

11. What is the line voltage for a 50 Hz, star-connected alternator with the following details:
flux = 500 mWb/pole; kd = 0.86; kp = 0.97; 45 turns per phase.

A. 83.34 V

 

B. 144.35 V

 

C. 4167 V

 

D. 7217 V

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

12. An increase in which of the following types of loads will cause the rotor field to weaken?

A. lagging power factor

 

B. unity power factor

 

C. leading power factor

 

D. DC excitation

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

13. What is the name of the process that is required before alternators are connected in parallel?

A. synchronicity

 

B. synchronisation

 

C. syncopation

 

D. sequencing

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

14. Which of the following methods is the most accurate for ensuring that the voltages of parallel connected alternators are in phase?

A. three dark lamps method

 

B. two bright one dark method

 

C. one bright two dark method

 

D. synchroscope

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

15. When the ‘three dark’ method is used, what does the rate of lamp flicker indicate?

A. supply frequency

 

B. difference in frequencies

 

C. supply voltage

 

D. difference in voltages

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

16. Which of the following will occur if the load on a single alternator increases?

A. The governor will open to increase the input power.

 

B. The governor will close to increase the input power.

 

C. The governor will open to decrease the input power.

 

D. The governor will close to decrease the input power.

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

17. Which of the following will occur if the load on a single alternator increases?

A. The voltage regulator will increase the field current to increase the output voltage.

 

B. The voltage regulator will decrease the field current to increase the output voltage.

 

C. The voltage regulator will increase the field current to maintain the output voltage.

 

D. The voltage regulator will decrease the field current to decrease the output voltage.

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

18. What is the main purpose of amortisseur windings in an alternator?

A. to reduce armature reaction

 

B. to reduce eddy current losses

 

C. to reduce hunting

 

D. to increase starting torque

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

19. Which of the following conditions can not be adjusted by the operator so that alternators can be connected in parallel?

A. the alternator and supply voltages

 

B. the alternator and supply phase relationship

 

C. the alternator and supply frequencies

 

D. the alternator and supply phase sequences

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

20. What action will increase the load taken by an alternator when it is operating in parallel with one other alternator?

A. Decrease its governor’s set point and increase the other alternator’s set point.

 

B. Increase its governor’s set point and decrease the other alternator’s set point.

 

C. Increase its governor’s set point and increase the other alternator’s set point.

 

D. Decrease its governor’s set point and decrease the other alternator’s set point.

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

21. What is the energy source for a UPS when it is supplying current to a load?

A. battery bank

 

B. engine driven alternator

 

C. mains supply

 

D. inverter

 

Difficulty: Easy
EPC 51, 65
Jenneson chapter 7
KS01-EG033A T7
 

 

22. Which of the following is not usually a prime factor in selecting an engine driven alternator?

A. availability of fuel

 

B. load power factor

 

C. alternator capacity

 

D. starting method

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T9
 

 

23. Which type of standby power supply would be most suitable for maintaining supply to a computer system in an office environment?

A. diesel engine driven alternator

 

B. unlimited power supply

 

C. surge protection device

 

D. uninterruptible power supply

 

Difficulty: Medium
EPC 51, 65
Jenneson chapter 7
KS01-EG033A T7
 

 

24. What factor directly controls the voltage output of an engine driven alternator when it is operating?

A. the engine governor set point

 

B. the supply frequency

 

C. the number of turns per phase

 

D. the field excitation

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T9
 

 

25. What is the rotor speed of a rotating four-pole synchronous motor that is connected to a 50 Hz supply?

A. 1500 rpm

 

B. 1440 rpm

 

C. 0 rpm

 

D. It depends on the percentage slip.

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

26. What is the basic operating principle for a synchronous motor?

A. Lenz’s law

 

B. electromagnetic induction

 

C. magnetic attraction between opposite poles

 

D. Ohm’s law

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

27. What is the name given to the positional difference between the rotor and the stator field of a synchronous motor?

A. slip

 

B. torque angle

 

C. phase angle

 

D. armature reaction

 

Difficulty: Easy
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

28. What is the effect of a change in the load on a synchronous motor with fixed excitation?

A. An increase in the load causes a decrease in the line current.

 

B. A decrease in the load causes an increase in the line current.

 

C. An increase in the load causes a decrease in the power factor.

 

D. An increase in the load causes an increase in the power factor.

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

29. What is the effect of a change in the field excitation of a synchronous motor with a constant load?

A. An increase in the field excitation causes a decrease in the line current at a lagging power factor.

 

B. An increase in the field excitation causes an increase in the line current at a lagging power factor.

 

C. An increase in the field excitation causes an increase in the line current at a leading power factor.

 

D. An increase in the field excitation causes a decrease in the line current at a leading power factor.

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

30. What is a synchronous capacitor?

A. an over-excited synchronous motor

 

B. an over-excited alternator

 

C. an under-excited synchronous motor

 

D. a synchronous motor operating at unity power factor

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

31. What is the purpose of an auxiliary motor?

A. It is a prime mover for an alternator.

 

B. It provides the field excitation for a synchronous machine.

 

C. It provides feedback to an automatic voltage regulator.

 

D. It brings a synchronous motor up to speed.

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

32. Which of the following is not a typical application for synchronous motors?

A. voltage control for transmission lines

 

B. power factor correction

 

C. air conditioner compressors

 

D. rock and ore crushing heads

 

Difficulty: Medium
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

33. When a synchronous machine is started as an induction motor, which of the following occurs?

A. The slip ring connections are open-circuited.

 

B. The stator voltage is increased.

 

C. The rotor field and stator field lock together.

 

D. The amortisseur windings act as a squirrel cage.

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

34. What effect does increasing the field excitation from a low value to a high value have on a synchronous motor that is operating on a constant load?

A. The torque will increase to a maximum and then decrease.

 

B. The power factor will increase to a maximum and then decrease.

 

C. The stator current will increase to a maximum and then decrease.

 

D. The rotor current will increase to a maximum and then decrease.

 

Difficulty: Hard
EPC 15, 19, 40
Jenneson chapter 7
KS02-EG006A T8
 

 

35. Which of the following is a single-phase synchronous motor?

A. reticence motor

 

B. reluctance motor

 

C. hysterics motor

 

D. shaded-pole motor

 

Jenneson chapter 7
 

 

36. What is the primary application for single-phase synchronous motors?

A. constant speed applications

 

B. high speed applications

 

C. constant torque applications

 

D. high torque applications

 

Jenneson chapter 7
 

 

37. What causes the rotor of a reluctance motor to continue rotating when the stator flux is low?

A. interference

 

B. induction

 

C. impetus

 

D. inertia

 

Jenneson chapter 7
 

 

38. What is a typical method for starting a reluctance motor?

A. use an auxiliary motor

 

B. start as an induction motor

 

C. start as a shaded pole motor

 

D. use a different number of rotor poles compared to stator poles

 

Jenneson chapter 7
 

 

39. What is a typical method for starting a hysteresis motor?

A. use an auxiliary motor

 

B. start as an induction motor

 

C. start as a shaded-pole motor

 

D. use a different number of rotor poles compared to stator poles.

 

Jenneson chapter 7
 

 

40. What is the benefit of a 400 Hz single-phase synchronous machine compared to one designed for 50 Hz?

A. It will deliver twice the power for the same physical size.

 

B. It will be 64 times smaller for the same output.

 

C. It will operate at a lower speed for the same number of poles.

 

D. There is no additional benefit.

 

Jenneson chapter 7
 

 

 

Chapter 07 Summary

Category # of Questions
Difficulty: Easy 10
Difficulty: Hard 8
Difficulty: Medium 16
EPC 15, 19, 40 32
EPC 51, 65 2
Jenneson chapter 7 40
KS01-EG033A T7 2
KS02-EG006A T8 30
KS02-EG006A T9 2

 

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