FREE BEE Bachelor of Electrical Engineering Power Systems and Machines Questions and Answers

Question 1

A 4-pole, 50 Hz, three-phase induction motor is running at 1440 RPM. What is the slip of the motor?

Accepted Answer

0.04

Answer

0.08

Answer

0.96

Answer

1.04

Question 2

In power system analysis, which of the following is a primary advantage of using the per-unit system?

Accepted Answer

It eliminates the need to refer impedances to the primary or secondary side of transformers.

Answer

It increases the precision of fault current calculations to more decimal places.

Answer

It directly provides the physical values of voltage and current at any point in the system.

Answer

It simplifies the calculation of transmission line capacitance and inductance.

Question 3

A power systems engineer observes that the receiving-end voltage of a long, lightly loaded transmission line is higher than the sending-end voltage. What is this phenomenon called, and what is its primary cause?

Accepted Answer

Ferranti Effect, caused by the line's capacitance and the resulting charging current.

Answer

Skin Effect, caused by non-uniform current distribution in the conductor.

Answer

Corona Effect, caused by ionization of air surrounding the conductor.

Answer

Proximity Effect, caused by the magnetic fields of adjacent conductors.

Question 4

An open-circuit test and a short-circuit test are performed on a single-phase transformer. What parameters are primarily determined from these two tests, respectively?

Accepted Answer

Core losses and copper losses

Answer

Copper losses and core losses

Answer

Voltage regulation and efficiency

Answer

Equivalent resistance and leakage reactance

Question 5

Which of the following best describes the 'transient stability' of a power system?

Accepted Answer

The ability of the system to remain in synchronism following a large, sudden disturbance like a fault or loss of a generator.

Answer

The ability of the system to remain in synchronism during and after small, slow-changing load variations.

Answer

The ability to withstand a temporary overvoltage without insulation breakdown.

Answer

The overall efficiency of the power system under peak load conditions.

Question 6

The capability curve of a synchronous generator defines the operational limits of the machine. Which of the following factors does NOT typically define a boundary on this curve?

Accepted Answer

Generator's synchronous speed

Answer

Stator armature heating limit

Answer

Prime mover power limit

Answer

Rotor field heating limit

A 4-pole, 50 Hz, three-phase induction motor is running at 1440 RPM.What is the slip of the motor?

A 4-pole, 50 Hz, three-phase induction motor is running at 1440 RPM.
What is the slip of the motor?