GATE EE Power Systems PYQs & Answers — Page 5

Questions 41–50 of 64. Imported answers require independent review unless marked reviewed.

Topic practice 64 questionsPage 5 of 7

Five alternators each rated 5 MVA, 13.2 kV with 25% of reactance on its own base are connected in parallel to a busbar. The short-circuit level in MVA at the bus is___________.

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The line currents of a three-phase four wire system are square waves with amplitude of 100 A. These three currents are phase shifted by 120° with respect to each other. The rms value of neutral current is

Your answerChoose one option.

0 A

100 A

300 A

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A three-phase 50 Hz, 400 kV transmission line is 300 km long. The line inductance is 1 mH/km per phase, and the capacitance is 0.01 μF/km per phase. The line is under open circuit condition at the receiving end and energized with 400 kV at the sending end, the receiving end line voltage in kV (round off to two decimal places) will be _____________.

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A 30 kV, 50 Hz, 50 MVA generator has the positive, negative, and zero sequence reactances of 0.25 pu, 0.15 pu, and 0.05 pu, respectively. The neutral of the generator is grounded with a reactance so that the fault current for a bolted LG fault and that of a bolted three-phase fault at the generator terminal are equal. The value of grounding reactance in ohms (round off to one decimal place) is __________.

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In the single machine infinite bus system shown below, the generator is delivering the real power of 0.8 pu at 0.8 power factor lagging to the infinite bus.

Diagram for Electrical Engineering question 51

The power angle of the generator in degrees (round off to one decimal place) is _____________.

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In a 132 kV system, the series inductance up to the point of circuit breaker location is 50 mH. The shunt capacitance at the circuit breaker terminal is 0.05 μF. The critical value of resistance in ohms required to be connected across the circuit breaker contacts which will give no transient oscillation is _________.

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Consider a lossy transmission line with

and

as the sending and receiving end voltages, respectively.

and

are the series impedance and reactance of the line, respectively. The steady-state stability limit for the transmission line will be

Your answerChoose one option.

greater than $\left|\frac{V_1 V_2}{X}\right|

less than $\left|\frac{V_1 V_2}{X}\right|

equal to

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The series impedance matrix of a short three-phase transmission line in phase coordinates is

. If the positive sequence impedance is (1 + j 10) Ω, and the zero sequence is (4 + j 31) Ω, then the imaginary part of

(in Ω) is _____ (up to 2 decimal places).

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The positive, negative and zero sequence impedances of a 125 MVA, three-phase, 15.5 kV, star-grounded, 50 Hz generator are j0.1 pu, j0.05 pu and j0.01 pu respectively on the machine rating base. The machine is unloaded and working at the rated terminal voltage. If the grounding impedance of the generator is j0.01 pu, then the magnitude of fault current for a b-phase to ground fault (in kA) is __________ (up to 2 decimal places).

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A 1000 × 1000 bus admittance matrix for an electric power system has 800 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are _____ (up to 2 decimal places).

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GATE EE Power Systems PYQs

Question 22

Question 38

Question 49

Question 50

Question 51

Question 52

Question 6

Question 20

Question 21

Question 22