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GATE EE 2021 : Power System Quiz 6
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Question 1
A 3 phase, 100MVA ,121KV generator has a sub transient reactance of 10 %. A 3-phase short-circuit occurs at its terminal. Find the value of fault MVA?
Question 2
Faults which involve ionized current paths are called?
Question 3
A 400 MVA, 11 kV, 50 Hz synchronous generator having Xd`` = 0.1 p.u is supplying a passive load of 200 MW at 11 kV. The load is purely resistive. Then the value of post fault current at generator terminal is
Question 4
A power system circuit diagram is given below. The generator have the reactance of X” = j0.12 p.u. transformer reactance is 15% on 75 mVA base. Assume the voltage before fault is 1 p.u. Find the value of current limiting reactor X such that the circuit breaker rating does not exceeds mVA. Choose base 400mVA as 100mVA.
Question 5
A salient pole, Y-connected generator without dampers is rated as 30 MVA, 15 kV and has direct axis sub-transient reactance of 0.25 p.u. The negative and zero sequence reactance are respectively 0.2 p.u., 0.05 p.u. The neutral of generator is solidly grounded. When a single line to ground fault occurs at the ‘a’ phase of generator terminal. Find the line to neutral voltage of ’b’ phase. (Phase sequence is abc).
Question 6
The bus bars of each of the two alternators of 25% reactance each are interconnected through tie-bar reactors of 10% each. What will be the equivalent impedance if a 3-phase fault occurs at any bus bar of an alternator?
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Sep 16ESE & GATE EE