SYNCHRONOUS GENERATOR MCQs – CHAPTER 6 DAE

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1. What is the main function of a synchronous alternator?
(A) To convert DC electric power into AC electric power
(B) To convert AC electric power into mechanical power
(C) To convert mechanical power into AC electric power
(D) To convert AC electric power into DC electric power

2. What is the name of the stationary part of a synchronous alternator that carries the armature winding?
(A) Stator
(B) Rotor
(C) Commutator
(D) Slip ring

3. What is the name of the rotating part of a synchronous alternator that produces the main field flux?
(A) Rotor
(B) Stator
(C) Commutator
(D) Slip ring

4. What is the term used to describe the speed of a synchronous alternator that produces AC power of a desired frequency?
(A) Synchronous speed
(B) Base speed
(C) Rated speed
(D) Critical speed

5. What is the formula for calculating the frequency of the induced EMF in a synchronous alternator?
(A) f = PN/120
(B) f = 120/PN
(C) f = NP/120
(D) f = 120/NP

6. What are the two types of rotor construction used in synchronous alternators?
(A) Cylindrical rotor type and squirrel cage type
(B) Salient-pole type and wound rotor type
(C) Salient-pole type and cylindrical rotor type
(D) Squirrel cage type and wound rotor type

7. What is the name of the factor that accounts for the reduction in induced EMF due to the coil span being less than a pole pitch?
(A) Form factor or waveform factor
(B) Distribution factor or winding factor
(C) Pitch factor or coil span factor
(D) Power factor or load factor

8. What is the name of the factor that accounts for the reduction in induced EMF due to the winding being distributed over several slots?
(A) Distribution factor or winding factor
(B) Pitch factor or coil span factor
(C) Form factor or waveform factor
(D) Power factor or load factor

9. What is the name of the factor that accounts for the difference between the RMS value and the average value of a sinusoidal waveform?
(A) Form factor or waveform factor
(B) Distribution factor or winding factor
(C) Pitch factor or coil span factor
(D) Power factor or load factor

10. What is the formula for calculating the RMS value of EMF per phase in a synchronous alternator?
(A) E_{ph} = 4.44 K_f K_p K_d ϕ N Z
(B) E_{ph} = 4.44 K_f K_p K_d ϕ N T
(C) E_{ph} = 4.44 K_f K_p K_d ϕ f Z
(D) E_{ph} = 4.44 K_f K_p K_d ϕ f T

11. What is the formula for calculating the line voltage in a star-connected synchronous alternator?
(A) E_L = 3 E_{ph}
(B) E_L = E_{ph}/√3
(C) E_L = √3 E_{ph}
(D) E_L = E_{ph}/3

12. What is the term used to describe the difference between the generated voltage and the terminal voltage of a synchronous alternator under load?
(A) Voltage fluctuation
(B) Voltage drop
(C) Voltage rise
(D) Voltage regulation

13. What are the two methods of controlling the output voltage of a synchronous alternator?
(A) Changing the speed and changing the load
(B) Changing the load and changing the power factor
(C) Changing the field excitation and changing the load
(D) Changing the speed and changing the field excitation

14. What are the two methods of controlling the frequency of a synchronous alternator?
(A) Changing the field excitation and changing the load
(B) Changing the speed and changing the field excitation
(C) Changing the speed and changing the load
(D) Changing the load and changing the power factor

15. What is the name of the phenomenon that causes the rotor of a synchronous alternator to oscillate about its synchronous position under load?
(A) Synchronizing or phase locking
(B) Hunting or phase swinging
(C) Damping or phase shifting
(D) Excitation or phase boosting

16. What is the name of the device that is used to provide a DC supply to the field winding of a synchronous alternator?
(A) Inverter
(B) Rectifier
(C) Exciter
(D) Converter

17. What is the name of the curve that shows the relation between the terminal voltage and the field current of a synchronous alternator at a given load and power factor?
(A) Q-curve
(B) I-curve
(C) P-curve
(D) V-curve

18. What is the name of the curve that shows the relation between the reactive power and the field current of a synchronous alternator at a given load and power factor?
(A) V-curve
(B) I-curve
(C) Q-curve
(D) P-curve

19. What is the name of the condition that must be satisfied for connecting two or more synchronous alternators in parallel?
(A) Matching condition
(B) Synchronizing condition
(C) Balancing condition
(D) Equalizing condition

20. What are the four parameters that must be equal for synchronizing two or more synchronous alternators in parallel?
(A) Voltage magnitude, frequency, phase sequence and power factor
(B) Voltage magnitude, frequency, power factor and phase angle
(C) Voltage magnitude, frequency, phase sequence and phase angle
(D) Voltage magnitude, frequency, power factor and phase sequence

21. What is the name of the device that is used to indicate the difference in phase angle between two alternating voltages for synchronizing purpose?
(A) Synchronizer
(B) Synchroscope
(C) Phase meter
(D) Phase shifter

22. What is the name of the device that is used to connect or disconnect a synchronous alternator from a busbar or another alternator?
(A) Circuit breaker
(B) Switch
(C) Relay
(D) Fuse

23. What is the effect of increasing the field excitation of a synchronous alternator operating at a constant load and power factor?
(A) The terminal voltage increases and the power factor becomes more leading
(B) The terminal voltage increases and the power factor becomes more lagging
(C) The terminal voltage decreases and the power factor becomes more leading
(D) The terminal voltage decreases and the power factor becomes more lagging

24. What is the effect of increasing the load of a synchronous alternator operating at a constant field excitation and power factor?
(A) The terminal voltage increases and the rotor angle increases
(B) The terminal voltage decreases and the rotor angle decreases
(C) The terminal voltage decreases and the rotor angle increases
(D) The terminal voltage increases and the rotor angle decreases

25. What is the name of the characteristic that shows the relation between the armature current and the field current of a synchronous alternator at a given terminal voltage?
(A) Open circuit characteristic (OCC)
(B) Zero power factor characteristic (ZPFC)
(C) Short circuit characteristic (SCC)
(D) Load saturation characteristic (LSC)

26. What is the name of the characteristic that shows the relation between the short circuit current and the field current of a synchronous alternator at a given speed?
(A) Open circuit characteristic (OCC)
(B) Short circuit characteristic (SCC)
(C) Zero power factor characteristic (ZPFC)
(D) Load saturation characteristic (LSC)

27. What is the name of the characteristic that shows the relation between the terminal voltage and the armature current of a synchronous alternator at a given field excitation and power factor?
(A) External characteristic (EC)
(B) Voltage regulation characteristic (VRC)
(C) Internal characteristic (IC)
(D) Synchronous impedance characteristic (SIC)

28. What is the name of the characteristic that shows the relation between the induced EMF and the armature current of a synchronous alternator at a given field excitation and power factor?
(A) Voltage regulation characteristic (VRC)
(B) Internal characteristic (IC)
(C) External characteristic (EC)
(D) Synchronous impedance characteristic (SIC)

29. What is the name of the method that uses the open circuit and short circuit characteristics to calculate the voltage regulation of a synchronous alternator?
(A) Potier triangle method or ZPF method
(B) Ampere turn method or MMF method
(C) Synchronous impedance method or EMF method
(D) ASA modified method or AIEE method

30. What is the name of the method that uses the zero power factor characteristics to calculate the voltage regulation of a synchronous alternator?
(A) Synchronous impedance method or EMF method
(B) Ampere turn method or MMF method
(C) ASA modified method or AIEE method
(D) Potier triangle method or ZPF method

31. What is the name of the phenomenon that causes a sudden change in terminal voltage and power factor of a synchronous alternator when it is overloaded?
(A) Loss of load or load rejection
(B) Loss of excitation or under excitation
(C) Loss of field or field failure
(D) Loss of synchronism or pull-out

32. What is the name of the device that is used to prevent the loss of synchronism of a synchronous alternator by reducing its output power when it is overloaded?
(A) Governor
(B) Limiter
(C) Relay
(D) Stabilizer

33. What is the name of the device that is used to improve the stability and damping of a synchronous alternator by injecting an auxiliary voltage in its field winding?
(A) Governor
(B) Stabilizer
(C) Limiter
(D) Relay

34. What is the name of the device that is used to measure and display the active power output of a synchronous alternator?
(A) Voltmeter
(B) Wattmeter
(C) Ammeter
(D) Frequency meter