GATE EE branch:ee PYQs & Answers — Page 56

Questions 551–560 of 715. Imported answers require independent review unless marked reviewed.

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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The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage source is shown in the figure. If

A, the rms value of fundamental component of the current is __________ A (up to 2 decimal places).

Diagram for Electrical Engineering question 23

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A separately excited dc motor has an armature resistance

. The field excitation is kept constant. At an armature voltage of 100 V, the motor produces a torque of 500 Nm at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radians/s) for an armature voltage of 150 V is ____ (up to 2 decimal places).

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Consider a unity feedback system with forward transfer function given by

The steady-state error in the output of the system for a unit-step input is ________ (up to 2 decimal places).

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A transformer with toroidal core of permeability

is shown in the figure. Assuming uniform flux density across the circular core cross-section of radius

, and neglecting any leakage flux, the best estimate for the mean radius

Diagram for Electrical Engineering question 26

Your answerChoose one option.

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A 0-1 Ampere moving iron ammeter has an internal resistance of 50 mΩ and inductance of 0.1 mH. A shunt coil is connected to extend its range to 0-10 ampere for all operating frequencies. The time constant in milliseconds and resistance in mΩ of the shunt coil respectively are

Your answerChoose one option.

2, 5.55

2, 1

2.18, 0.55

11.1, 2

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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

Your answerChoose one option.

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Consider the two bus power system network with given loads as shown in the figure. All the values shown in the figure are in per unit. The reactive power supplied by generator G₁ and G₂ are QG₁ and QG₂ respectively. The per unit values of QG₁, QG₂, and line reactive power loss (Qloss) respectively are

Diagram for Electrical Engineering question 29

Your answerChoose one option.

5.00, 12.68, 2.68

6.34, 10.00, 1.34

6.34, 11.34, 2.68

5.00, 11.34, 1.34

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The per-unit power output of a salient-pole generator which is connected to an infinite bus, is given by the expression,

, where

is the load angle. Newton-Raphson method is used to calculate the value of

for

pu. If the initial guess is 30°, then its value (in degree) at the end of the first iteration is

Your answerChoose one option.

15°

28.48°

28.74°

31.20°

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GATE EE branch:ee PYQs

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

Question 27

Question 28

Question 29

Question 30