GATE EE 2016 Set 1 — Question 51
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.NAT+2 / -0HardUnsymmetrical Faults (LG, LL, LLG)Fault AnalysisPower SystemsSymmetrical Components
Power Systems → Fault Analysis → Symmetrical Components
Last updated
Question
A 30 MVA, 3-phase, 50 Hz, 13.8 kV, star-connected synchronous generator has positive, negative and zero sequence reactances, 15%, 15% and 5% respectively. A reactance () is connected between the neutral of the generator and ground. A double line to ground fault takes place involving phases ‘b’ and ‘c’, with a fault impedance of p.u. The value of (in p.u.) that will limit the positive sequence generator current to 4270 A is _________.
Correct answer
1.05 to 1.15
Solution
1. Base currentThe required positive sequence current in per unit is2. Sequence network connection for a double line to ground faultFor an LLG fault on phases b and c through a fault impedance to ground, the positive, negative and zero sequence networks are in parallel at the fault, with and in series with the zero sequence network:With p.u., , , , :All impedances are reactances, so the factors cancel in magnitude:3. Solve for (The result is very sensitive to rounding of , so keep at least four significant figures in the intermediate steps.)Answer: p.u.
Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE EE question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Fault Analysis
2026 Set 1 Q18Consider a power system with buses, of which are generator buses and the remaining are…2026 Set 1 Q19The initial three-phase voltage phasors (, , and ) at a bus of a…2026 Set 1 Q39In the circuit shown, the phase currents are A…2026 Set 1 Q40The operating characteristic of a reactance relay is given by , where is the…2026 Set 1 Q41A three-phase two-winding transformer has a voltage transformation ratio…