BEE Power Systems Engineering 3

Question 1

A transmission line has a sending-end voltage of 230 kV and a receiving-end voltage of 220 kV. What is the voltage regulation?

Accepted Answer

4.55%

Answer

Voltage regulation = (V_NL − V_FL) / V_FL × 100 = (230 − 220) / 220 × 100 ≈ 4.55%.

Question 2

In power systems, what is the purpose of an auto-recloser on a distribution feeder?

Accepted Answer

Automatically restore service after a temporary fault by re-energizing the line

Answer

Auto-reclosers automatically open on a fault and reclose after a brief delay, restoring service if the fault was transient (e.g., lightning, tree branch).

Question 3

What is the significance of the 'critical clearing time' in transient stability analysis?

Accepted Answer

The maximum fault duration for which the system remains transiently stable

Answer

Critical clearing time is the maximum time a fault can persist before the generator loses synchronism; faults cleared faster than this keep the system stable.

Question 4

In a power transformer, what causes hysteresis and eddy current losses?

Accepted Answer

Alternating magnetic flux in the core material

Answer

Both hysteresis and eddy current losses are core (no-load) losses caused by the cyclic magnetization and induced circulating currents in the iron core.

Question 5

A 3-phase, 60 Hz synchronous generator has 4 poles. What is its synchronous speed?

Accepted Answer

1800 RPM

Answer

Synchronous speed Ns = 120f/P = 120×60/4 = 1800 RPM.

BEE - Bachelor of Electrical Engineering Practice Test

BEE - Bachelor of Electrical Engineering Practice Test

BEE Power Systems Engineering 3