GATE EE 2018 Set 1 — Question 38
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.MCQ+2 / -0.67MediumUnsymmetrical Faults (LG, LL, LLG)Fault AnalysisPower Systems
Power Systems → Fault Analysis → Unsymmetrical Faults (LG, LL, LLG)
Last updated
Question
The positive, negative and zero sequence impedances of a three phase generator are and respectively. For a line-to-line fault with fault impedance , the fault current is , where is the fault current with zero fault impedance. The relation between and is
Correct answer
(A) Z_f = ((Z₁+Z₂)(1-k))/(k)
Solution
For a line-to-line fault with fault impedance , the fault current is given by:
When the fault impedance is zero (), the fault current is:
Given that , we can substitute the expressions:
Canceling from both sides:
Rearranging to solve for :
Therefore, option (A) is correct.
When the fault impedance is zero (), the fault current is:
Given that , we can substitute the expressions:
Canceling from both sides:
Rearranging to solve for :
Therefore, option (A) is correct.
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…