GATE EE year:2017 PYQs & Answers — Page 10 — Exam Papers

Questions 91–100 of 130. Imported answers require independent review unless marked reviewed.

Topic practice 130 questionsPage 10 of 13

Two parallel connected, three-phase, 50Hz, 11 kV, star-connected synchronous machines A and B, are operating as synchronous condensers. They together supply 50 MVAR to a 11 kV grid. Current supplied by both the machines are equal. Synchronous reactances of machine A and machine B are 1Ω and 3Ω, respectively. Assuming the magnetic circuit to be linear, the ratio of excitation current of machine A to that of machine B is ________. (Give the answer up to two decimal places.)

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Consider the system described by the following state space representation

If

is a unit step input and

the value of output

at

sec (rounded off to three decimal places) is __________

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A 220 V DC series motor runs drawing a current of 30 A from the supply. Armature and field circuit resistances are 0.4 Ω and 0.1 Ω, respectively. The load torque varies as the square of the speed. The flux in the motor may be taken as being proportional to the armature current. To reduce the speed of the motor by 50%, the resistance in ohms that should be added in series with the armature is ________. (Give the answer up to two decimal places.)

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A 10 ½ digit timer counter possesses a base clock of frequency 100 MHz. When measuring a particular input, the reading obtained is the same in (i) Frequency mode of operation with a gating time of one second and (ii) Period mode of operation (in the x 10 ns scale). The frequency of the unknown input (reading obtained) in Hz is _____.

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A three-phase, three winding

(1.1 kV/6.6 kV/400 V) transformer is energized from AC mains at the 1.1 kV side. It supplies 900 kVA load at 0.8 power factor lag from the 6.6 kV winding and 300 kVA load at 0.6 power factor lag from the 400 V winding. The RMS line current in ampere drawn by the 1.1 kV winding from the mains is ________. (Give the answer up to one decimal place.)

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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.)

Diagram for Electrical Engineering question 48

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A separately excited DC generator supplies 150 A to a 145 V DC grid. The generator is running at 800 RPM. The armature resistance of the generator is 0.1Ω. If the speed of the generator is increased to 100 RPM, the current in amperes supplied by the generator to the DC grid is ________. (Give the answer up to one decimal place.)

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For the synchronous sequential circuit shown below, the output Z is zero for the initial conditions

.

Diagram for Electrical Engineering question 49

The minimum number of clock cycles after which the output Z would again become zero is __________

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For a system having transfer function

, a unit step input is applied at time

. The value of the response of the system at

sec (rounded off to three decimal places) is ________.

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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.)

Diagram for Electrical Engineering question 50

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