Alternator and Induction Generator MCQs (Part-5)

What does the excitation system of an alternator do?

A Regulates the rotor speed
B Supplies DC power to the rotor winding
C Converts mechanical energy into electrical energy
D Controls the stator current

What type of alternator is commonly used in hydroelectric power plants?

A High-speed alternator
B Salient pole alternator
C Induction alternator
D Permanent magnet alternator

How does the rotor of an alternator generate a magnetic field?

A By using permanent magnets
B By rotating at synchronous speed and using an external power source
C By generating an electric current through the rotor shaft
D By using capacitors to provide a magnetic field

In a three-phase alternator, how are the phases spaced?

A 90 degrees
B 180 degrees
C 120 degrees
D 360 degrees

What happens when an induction generator is disconnected from the grid?

A It continues to generate power independently
B It shuts down immediately
C It starts consuming reactive power from the grid
D It starts to generate DC power

What determines the frequency of the output voltage in an alternator?

A The load on the alternator
B The rotor speed and the number of poles
C The stator windings
D The excitation voltage

What is the primary function of stator windings in an alternator?

A To create a rotating magnetic field
B To produce alternating current
C To supply mechanical energy to the rotor
D To regulate the excitation voltage

What is the main difference between a synchronous generator and an induction generator?

A Synchronous generators require external excitation; induction generators do not
B Synchronous generators operate at constant speed; induction generators operate at variable speed
C Synchronous generators generate DC power; induction generators generate AC power
D Synchronous generators are used in renewable energy systems; induction generators are not

What is the effect of increasing the excitation current in an alternator?

A The voltage output increases
B The voltage output decreases
C The frequency increases
D The power factor improves

Why is the use of damper windings important in synchronous generators?

A To reduce eddy current losses
B To prevent rotor hunting
C To improve efficiency
D To regulate the output voltage

What is the primary function of a voltage regulator in an alternator?

A To adjust the rotor speed
B To regulate the field current and maintain stable voltage
C To synchronize the alternator with the grid
D To control the load on the alternator

What is the effect of low power factor in an alternator?

A Increases reactive power and lowers system efficiency
B Increases active power generation
C Decreases the alternator’s capacity
D Improves system stability

What is an induction generator’s slip?

A The difference between the rotor speed and the synchronous speed
B The difference between the rotor and stator voltage
C The amount of reactive power generated
D The difference in phase angle between stator and rotor

How are induction generators typically excited?

A Using an external DC power source
B By capacitors connected to the stator
C By a permanent magnet in the rotor
D By an internal source of reactive power

How does a three-phase alternator handle power factor control?

A By increasing the excitation current
B By adjusting the rotor speed
C By using an external power factor correction device
D By adjusting the stator resistance

What is the primary function of a synchronous condenser?

A To reduce active power losses
B To provide reactive power and improve voltage stability
C To convert DC to AC
D To synchronize an alternator with the grid

What is the synchronous speed of an alternator determined by?

A The stator resistance
B The rotor speed
C The supply frequency and the number of poles
D The excitation voltage

Why are the rotor poles designed to be salient in some alternators?

A To reduce losses
B To allow operation at low speeds
C To improve voltage regulation
D To increase the efficiency

What is the effect of increasing the number of poles in an alternator?

A Increases the rotor speed
B Decreases the synchronous speed
C Increases the frequency of the output
D Increases the excitation current

What is the typical use of a single-phase alternator?

A Large-scale power generation
B Small residential power systems
C High-voltage transmission systems
D Industrial machinery