Electrical Engineering GATE 2021 Questions with Answer

Ques 14 Control Systems

In the given figure, plant $G p (s) = 2.2 / ((1 + 0.1s)(1 + 0.4s)(1 + 1.2s))$ , and compensator $G c (s) = K( (1 + T 1 s) / (1 + T 2 s) )$ . The external disturbance input is $D(s).$ It is desired that when the disturbance is a unit step, the steady-state error should not exceed 0.1 unit. The minimum value of K is _______. (Round off to 2 decimal places.)

11.00 is the correct answer.

Ques 15 Control Systems

The state space representation of a first-order system is given as
$ẋ = -x + u$
$y = x$
where, x is the state variable, u is the control input, and y is the controlled output. Let $u = -Kx$ be the control law, where K is the controller gain. To place a closed-loop pole at -2, the value of K is _______.

1 is the correct answer.

Ques 16 Control Systems

For the closed-loop system shown, the transfer function E(s)/R(s) is:

G / (1 + GH)

(GH) / (1 + GH)

1 / (1 + GH)

1 / (1 + G)

Ques 17 Digital Electronics

A CMOS Schmitt-trigger inverter has a low output level of 0 V and a high output level of 5 V. It has input thresholds of 1.6 V and 2.4 V. The input capacitance and output resistance of the Schmitt-trigger are negligible. The frequency of the oscillator shown is _______ Hz. (Round off to 2 decimal places.)

1190.48 is the correct answer.

Ques 18 Digital Electronics

A 16-bit synchronous binary up-counter is clocked with a frequency f_CLK. The two most significant bits are OR-ed together to form an output Y. Measurements show that Y is periodic, and the duration for which Y remains high in each period is 24 ms. The clock frequency f_CLK is _______ MHz. (Round off to 2 decimal places.)

is the correct answer.

Ques 19 Digital Logic

A counter is constructed with three D flip-flops. The input-output pairs are named (D₀, Q₀), (D₁, Q₁), and (D₂, Q₂), where the subscript 0 denotes the least significant bit. The output sequence is desired to be the Gray-code sequence 000, 001, 011, 010, 110, 111, 101, and 100, repeating periodically. Note that the bits are listed in the $Q 2 Q 1 Q 0$ format. The combinational logic expression for $D 1$ is

Q₂Q₁Q₀

Q₂Q₀ + Q₁Q₀

Q₂Q₁ + Q₂Q₁

Ques 20 Electrical Machines

A belt-driven DC shunt generator running at 300 RPM delivers 100 kW to a 200 V DC grid. It continues to run as a motor when the belt breaks, taking 10 kW from the DC grid. The armature resistance is 0.025 Ω, field resistance is 50 Ω, and brush drop is 2 V. Ignoring armature reaction, the speed of the motor is _______ RPM. (Round off to 2 decimal places.)

276.75 is the correct answer.

Ques 21 Electrical Machines

An 8-pole, 50 Hz, three-phase, slip-ring induction motor has an effective rotor resistance of 0.08 Ω per phase. Its speed at maximum torque is 650 RPM. The additional resistance per phase that must be inserted in the rotor to achieve maximum torque at start is _______ Ω. (Round off to 2 decimal places.) Neglect magnetizing current and stator leakage impedance. Consider equivalent circuit parameters referred to stator.

1.16 is the correct answer.

Ques 22 Electrical Machines

Consider the table given:

Constructional feature	Machine type	Mitigation
(P) Damper bars	(S) Induction motor	(X) Hunting
(Q) Skewed rotor slots	(T) Transformer	(Y) Magnetic locking
(R) Compensating winding	(U) Synchronous machine	(Z) Armature reaction
	(V) DC machine

The correct combination that relates the constructional feature, machine type and mitigation is:

P-V-X, Q-U-Z, R-T-Y

P-U-X, Q-S-Y, R-V-Z

P-T-Y, Q-V-Z, R-S-X

P-U-X, Q-V-Y, R-T-Z

Ques 23 Electrical Machines

Inductance is measured by

Schering bridge

Maxwell bridge

Kelvin bridge

Wien bridge

Ques 24 Electrical Machines

The power input to a 500 V, 50 Hz, 6-pole, 3-phase induction motor running at 975 RPM is 40 kW. The total stator losses are 1 kW. If the total friction and windage losses are 2.025 kW, then the efficiency is _______ %.

is the correct answer.

Ques 25 Electrical Machines

In a single-phase transformer, the total iron loss is 2500 W at nominal voltage of 440 V and frequency 50 Hz. The total iron loss is 850 W at 220 V and 25 Hz. Then, at nominal voltage and frequency, the hysteresis loss and eddy current loss respectively are

1600 W and 900 W

900 W and 1600 W

250 W and 600 W

600 W and 250 W

Ques 26 Electromagnetic Fields

Which one of the following vector functions represents a magnetic field ̂B? ( x̂, ŷ, and ẑ are unit vectors along x-axis, y-axis, and z-axis, respectively)

10x𝑥̂ + 20y𝑦̂ − 30z𝑧̂

10y𝑥̂ + 20x𝑦̂ − 10z𝑧̂

10z𝑥̂ + 20y𝑦̂ − 30x𝑧̂

10x𝑥̂ − 30z𝑦̂ + 20y𝑧̂

1 2 3 4 5

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Electrical Engineering GATE 2021 Questions with Answer