Electrical Engineering Gate Yearwise 




Electrical Engineering GATE 2017 Set II Questions with Answer

Ques 40 Power Electronics

The figure below shows a half-bridge voltage source inverter supplying an RL-load with R=40 Ω and L=(0.3/π)H. The desired fundamental frequency of the load voltage is 50 Hz. The switch control signals of the converter are generated using sinusoidal pulse width modulation with modulation index, M=0.6. At 50 Hz, the RL-load draws an active power of 1.44 kW. The value of DC source voltage VDC in volts is

A

300√2

B

500

C

500√2

D

1000√2



Ques 41 Power Electronics

In the circuit shown in the figure, the diode used is ideal. The input power factor is ________. (Give the answer up to two decimal places.)


0.707 is the correct answer.


Ques 42 Power Electronics

In the circuit shown all elements are ideal and the switch S is operated at 10 kHz and 60% duty ratio. The capacitor is large enough so that the ripple across it is negligible and at steady state acquires a voltage as shown. The peak current in amperes drawn from the 50 V DC source is ________. (Give the answer up to one decimal place.)


40 is the correct answer.


Ques 43 Power Electronics

A phase-controlled, single-phase, full-bridge converter is supplying a highly inductive DC load. The converter is fed from a 230 V 50 Hz, AC source. The fundamental frequency in Hz of the voltage ripple on the DC side is

A

25

B

50

C

100

D

300



Ques 44 Power Electronics

In the circuit shown, the diodes are ideal, the inductance is small, and Io≠0. Which one of the following statements is true?

A

D1 conducts for greater than 180° and D2 conducts for greater than 180°

B

D2 conducts for more than 180° and D1 conducts for 180°

C

D1 conducts for 180° and D2 conducts for 180°

D

D1 conducts for more than 180° and D2 conducts for 180°



Ques 45 Power Systems

The figure shows the per-phase representation of a phase-shifting transformer connected between buses 1 and 2, where α is a complex number with non-zero real and imaginary parts. For the given circuit, Ybus and Zbus are bus admittance matrix and bus impedance matrix, respectively, each of size 2x2. Which one of the following statements is true?

A

Both Ybus and Zbus are symmetric

B

Ybus is symmetric and Zbus is unsymmetric

C

Ybus is unsymmetric and Zbus is symmetric

D

Both Ybus and Zbus are unsymmetric



Ques 46 Power Systems

The nominal-π circuit of a transmission line is shown in the figure.

Impedance Z = 100∠80° Ω and reactance X = 3300 Ω. The magnitude of the characteristic impedance of the transmission line, in Ω, is ________. (Give the answer up to one decimal place.)


406.2 is the correct answer.


Ques 47 Power Systems

In a load flow problem solved by Newton-Raphson method with polar coordinates, the size of the Jacobian is 100x100. If there are 20 PV buses in addition to PQ buses and a slack bus, the total number of buses in the system is ________.


61 is the correct answer.


Ques 48 Signals and Systems

The mean square value of the given periodic waveform f(t) is ________.


6 is the correct answer.


Ques 49 Signals and Systems

The output y(t) of the following system is to be sampled, so as to reconstruct it from its samples uniquely. The required minimum sampling rate is

A

1000 samples/s

B

1500 samples/s

C

2000 samples/s

D

3000 samples/s



Ques 50 Signals and Systems

A cascade system having the impulse responses h1(n) = {1, -1} and h2(n) = {1, 1} is shown in the figure below, where symbol ↑ denotes the time origin.

The input sequence x(n) for which the cascade system produces an output sequence y(n) = {1, 2, 1, -1, -2, -1} is

A

x(n) = {1, 2, 1, 1}

B

x(n) = {1, 1, 2, 2}

C

x(n) = {1, 1, 1, 1}

D

x(n) = {1, 2, 2, 1}



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