GATE EE · Power Systems

Switch Gear And Protection Practice Questions

Generate GATE-level questions on Protection systems. Focus on: 1. Relays: Overcurrent, Directional, Distance (Mho/Reactance), and Differential protection. 2. Circuit Breakers: Arc interruption theory, Restriking voltage, and RRRV. 3. Protection of Generators, Transformers, and Transmission lines.

25 questions · 5 PYQs · 0 AI practice · GATE EE 2027

Q21GATE 2004MCQ

The transmission line distance protection relay having the property of being inherently directional is

🚀 Solve in Practice Mode

📖 Explanation

MHO relay has the property of being inherently directional. $Q=K_3|V||I| \cos (\theta -\tau )-(-K_1)|V|^2$ For relay operation

\begin{aligned} Q \gt 0 \\ K_3|V||I| \cos (\theta -\tau )-(-K_1)|V|^2 \gt 0 \\ \frac{|V|}{|I|}=|Z|\lt \frac{K_3}{-K_1} \cos (\theta -\tau )\;\;..(i) \end{aligned}

Q22GATE 2004MCQ

A lightning stroke discharges impulse current of 10 kA (peak) on a 400 kV transmission line having surge impedance of 250 $\Omega$ . The magnitude of transient over-voltage travelling waves in either direction assuming equal distribution from the point of lightning strike will be

🚀 Solve in Practice Mode

📖 Explanation

The impulse current of 10 KA (peak) will be equally divided in both directions since there is equal distribution on both sides. Then, magnitude of transient over voltage $=10000 A \times 25=2500kV$ (Assumed ideal impulse) Impulse available for zero time.