EGSA Generator and Alternator Principles Questions and Answers

Question 1

A technician is troubleshooting a self-excited generator that fails to build up any voltage when started.
The prime mover is confirmed to be operating at the correct speed.
Which of the following is the most likely initial cause for this failure?

Accepted Answer

Loss of residual magnetism in the field poles.

Answer

The automatic voltage regulator (AVR) is faulty.

Answer

The generator's field windings are open.

Answer

The exciter circuit breaker has tripped.

Question 2

What is the primary function of an Automatic Voltage Regulator (AVR) in an alternator?

Accepted Answer

To maintain a constant output voltage under varying loads.

Answer

To adjust the prime mover's speed to control frequency.

Answer

To protect the alternator from overcurrent conditions.

Answer

To ensure the phase sequence of the output is correct.

Question 3

A 4-pole alternator is operating at a speed of 1800 RPM. What is the frequency of the generated AC voltage?

Accepted Answer

60 Hz

Answer

50 Hz

Answer

120 Hz

Answer

45 Hz

Question 4

Which of the following principles is used to determine the direction of induced current in the conductors of a generator's armature?

Accepted Answer

Fleming's Right-Hand Rule

Answer

Fleming's Left-Hand Rule

Answer

Lenz's Law

Answer

Ohm's Law

Question 5

In a synchronous generator, what is the purpose of the damper windings (or amortisseur windings) located in the rotor pole faces?

Accepted Answer

To dampen rotor oscillations and assist in starting.

Answer

To increase the main field strength for higher voltage output.

Answer

To provide the main excitation for the rotor.

Answer

To cool the rotor during high-load operation.

Question 6

A technician observes that the terminal voltage of an alternator drops significantly as the load increases, even though the AVR appears to be functioning. Which of the following is a primary internal factor causing this voltage drop?

Accepted Answer

The alternator's internal synchronous reactance.

Answer

A decrease in prime mover speed.

Answer

An increase in the excitation current.

Answer

A change in the ambient temperature.

A technician is troubleshooting a self-excited generator that fails to build up any voltage when started.The prime mover is confirmed to be operating at the correct speed.Which of the following is the most likely initial cause for this failure?

A technician is troubleshooting a self-excited generator that fails to build up any voltage when started.
The prime mover is confirmed to be operating at the correct speed.
Which of the following is the most likely initial cause for this failure?