Electrical Engineering Gate Yearwise 




Electrical Engineering Gate 2020 Questions with Answer

Ques 53 GATE 2020

In the dc-dc converter circuit shown, switch Q is switched at a frequency of 10 kHz with a duty ratio of 0.6. All components of the circuit are ideal, and the initial current in the inductor is zero. Energy stored in the inductor in mJ (rounded off to 2 decimal places) at the end of 10 complete switching cycles is _______


(4.95 to 5.05) is the correct answer.

Ques 54 GATE 2020

A single-phase, full-bridge, fully controlled thyristor rectifier feeds a load comprising a 10 Ω resistance in series with a very large inductance. The rectifier is fed from an ideal 230 V, 50 Hz sinusoidal source through cables which have negligible internal resistance and a total inductance of 2.28 mH. If the thyristors are triggered at an angle α=45o the commutation overlap angle in degree (rounded off to 2 decimal places) is _______


(4.51 to 5.10) is the correct answer.

Ques 55 GATE 2020

A lossless transmission line with 0.2 pu reactance per phase uniformly distributed along the length of the line, connecting a generator bus to a load bus, is protected up to 80% of its length by a distance relay placed at the generator bus. The generator terminal voltage is 1 pu. There is no generation at the load bus. The threshold pu current for operation of the distance relay for a solid three phase-to-ground fault on the transmission line is closest to:

A

1.00

B

3.61

C

5.00

D

6.25


(d) is the correct answer.

Ques 56 GATE 2020

Out of the following options, the most relevant information needed to specify the real power (P) at the PV buses in a load flow analysis is

A

solution of economic load dispatch

B

rated power output of the generator

C

rated voltage of the generator

D

base power of the generator


(a) is the correct answer.

Ques 57 GATE 2020

A single 50 Hz synchronous generator on droop control was delivering 100 MW power to a system. Due to increase in load, generator power had to be increased by 10 MW, as a result of which, system frequency dropped to 49.75 Hz. Further increase in load in the system resulted in a frequency of 49.25 Hz. At this condition, the power in MW supplied by the generator is _______ (rounded off to 2 decimal places).


(123.00 to 135.00) is the correct answer.

Ques 58 GATE 2020

Two buses, i and j, are connected with a transmission line of admittance Y, at the two ends of which there are ideal transformers with turns ratios as shown. Bus admittance matrix for the system is:

A

B

C

D


(c) is the correct answer.

Ques 59 GATE 2020

Bus 1 with voltage magnitude V1 = 1.1 pu is sending reactive power Q12 towards bus 2 with voltage magnitude V2 = 1 pu through a lossless transmission line of reactance X.
Keeping the voltage at bus 2 fixed at 1 pu, magnitude of voltage at bus 1 is changed so that the reactive power Q12 sent from bus 1 is increased by 20%.
Real power flow through the line under both the conditions is zero.
The new value of the voltage magnitude, V1, in pu (rounded off to 2 decimal places), at bus 1 is __________.


(1.11 to 1.13) is the correct answer.

Ques 60 GATE 2020

Which of the following statements is true about the two sided Laplace transform?

A

It exists for every signal that may or may not have a Fourier transform.

B

It has no poles for any bounded signal that is non-zero only inside a finite time interval.

C

The number of finite poles and finite zeroes must be equal.

D

If a signal can be expressed as a weighted sum of shifted one sided exponentials, then its Laplace Transform will have no poles.


(b) is the correct answer.

Ques 61 GATE 2020

Consider a signal x[n]=(1/2)n 1[n], where 1[n]=0 if n<0 and 1[n]=1 if n≥0. The z-transform of x[n-k], k>0 is z-k/(1-(1/2)z-1) with region of convergence being

A

|z|<2

B

|z|>2

C

|z|<1/2

D

|z|>1/2


(d) is the correct answer.

Ques 62 GATE 2020

xR and xA are, respectively, the rms and average values of x(t)=x(t-T), and similarly, yR and yA are, respectively, the rms and average values of y(t)=kx(t). k, T are independent of t. Which of the following is true?

A

yA=kxA; yR=kxR

B

yA=kxA; yR≠kxR

C

yA≠kxA; yR=kxR

D

yA≠kxA; yR≠kxR


(a) is the correct answer.

Ques 63 GATE 2020

Suppose for input x(t) a linear time-invariant system with impulse response h(t) produces output y(t) so that x(t) * h(t) = y(t).
Further, if |x(t)| * |h(t)| = z(t), which of the following statements is true?

A

For all t ∈ (-∞, ∞), z(t) ≤ y(t)

B

For some but not all t ∈ (-∞, ∞), z(t) ≤ y(t)

C

For all t ∈ (-∞, ∞), z(t) ≥ y(t)

D

For some but not all t ∈ (-∞, ∞), z(t) ≥ y(t)


(c) is the correct answer.

Ques 64 GATE 2020

Which of the following options is true for a linear time-invariant discrete time system that obeys the difference equation:
y[n] - a y[n - 1] = b0x[n] - b1x[n - 1]

A

y[n] is unaffected by the values of x[n-k]; k>2.

B

The system is necessarily causal.

C

The system impulse response is non-zero at infinitely many instants.

D

When x[n]=0 n<0, the function y[n]; n>0 is solely determined by the function x[n].


(c) is the correct answer.

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