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GATE EE 2021 : Power System Quiz 7 (App update required to attempt this test)

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Question 1

A 50 Hz balanced three-phase, Y-connected supply is connected to a balanced three phase Y-connected load. If the instantaneous phase-α of the supply voltage is Vcos(ωt) and the phase-α of the load current is Icos(ωt–), the instantaneous three-phase power is

Question 2

In an isolated neutral system, when a single line to ground fault occurs

Question 3

A 345-kV transmission line a series impedance of (4+j60) Ω and a shunt admittance of j2 × 10–3 S. Using 100 MVA and the line voltage as base values the per unit admittance of line is ja p.u. The value of ‘a’ is ________.

Question 4

Two identical unloaded generators are connected in parallel as shown below. Both the generators are having positive, negative and zero sequence impedance of j0.8 p.u., j0.2 p.u. and 0.3 p.u. respectively. If pre-fault voltage is 1 p.u. for a line to ground fault at the terminals of the generator, the fault current magnitude (in p.u.) is ___________. (Assume neutral impedance, Zn = j0.02 p.u.)

Question 5

A 15 MVA, 11 kV, alternator has positive, negative and zero sequence reactance are 0.3 p.u., 0.2 p.u. and 0.05 p.u. respectively. Find the value of resistance to be added in the generator neutral so that the fault current of LG fault does not exceed 1.5 times of rated line current.

Question 6

Find the value of fault current F in the figure given below?
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Sep 17ESE & GATE EE