GATE Electrical Engineering Practice Quiz

Question 1

A percentage differential protection scheme is used for a power transformer. Which quantity is primarily used as the restraining quantity in a biased differential relay?

Accepted Answer

Average of the magnitudes of currents entering and leaving the protected zone

Question 2

For a transmission line protected by a distance relay, the relay fundamentally measures which electrical quantity to estimate the fault location?

Accepted Answer

Apparent impedance seen from the relay location

Question 3

A distance relay on a long EHV line may underreach during a close-in fault with heavy DC offset and CT saturation. The most direct reason is that

Accepted Answer

the measured current is reduced, so the apparent impedance V/I becomes larger than actual

Question 4

For a single line-to-ground fault on a solidly grounded system, a ground distance relay commonly uses a residual compensation factor because

Accepted Answer

zero-sequence impedance differs from positive-sequence impedance, affecting the apparent impedance seen by the relay

Question 5

A directional overcurrent relay is required in a power system mainly when

Accepted Answer

fault current can flow in either direction due to multiple sources

GATE Electrical Engineering Group Discussion

Students preparing for GATE Electrical Engineering

GATE Electrical Engineering — Group Discussion