Electrical Engineering GATE 2020 Questions with Answer

Ques 53 Power Electronics

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 Power Electronics

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=45^o the commutation overlap angle in degree (rounded off to 2 decimal places) is _______

4.51 to 5.10 is the correct answer.

Ques 55 Power Systems

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:

1.00

3.61

5.00

6.25

Ques 56 Power Systems

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

solution of economic load dispatch

rated power output of the generator

rated voltage of the generator

base power of the generator

Ques 57 Power Systems

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 Power Systems

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:

Ques 59 Power Systems

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 Signals and Systems

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

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

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

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

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

Ques 61 Signals and Systems

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

|z|<2

|z|>2

|z|<1/2

|z|>1/2

Ques 62 Signals and Systems

x_R and x_A are, respectively, the rms and average values of x(t)=x(t-T), and similarly, y_R and y_A are, respectively, the rms and average values of y(t)=kx(t). k, T are independent of t. Which of the following is true?

y_A=kx_A; y_R=kx_R

y_A=kx_A; y_R≠kx_R

y_A≠kx_A; y_R=kx_R

y_A≠kx_A; y_R≠kx_R

Ques 63 Signals and Systems

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?

For all t ∈ (-∞, ∞), z(t) ≤ y(t)

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

For all t ∈ (-∞, ∞), z(t) ≥ y(t)

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

Ques 64 Signals and Systems

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]

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

The system is necessarily causal.

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

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

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Electrical Engineering GATE 2020 Questions with Answer