Electrical Engineering
GATE EE Electrical Machines PYQs
Build your understanding with focused practice from past exam papers.
Questions 31–40 of 79. Imported answers require independent review unless marked reviewed.
Question 35
Open questionEENAT1 markNeeds review
The frequencies of the stator and rotor currents flowing in a three-phase 8-pole induction motor are 40 Hz and 1 Hz, respectively. The motor speed, in rpm, is ________________. (round off to nearest integer)
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Open questionEENAT2 marksNeeds review
A 20 MVA, 1.2 kV, 4-pole, 50 Hz alternator has an inertia constant of 15 MJ/MVA. If the input and output powers of the alternator are 15 MW and 10 MW, respectively, the angular acceleration in mechanical degree/s² is __________. (round off to nearest integer)
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 62
Open questionEENAT2 marksNeeds review
A 280 V, separately excited DC motor with armature resistance of 1 Ω and constant field excitation drives a load. The load torque is proportional to the speed. The motor draws a current of 30 A when running at a speed of 1000 rpm. Neglect frictional losses in the motor. The speed, in rpm, at which the motor will run, if an additional resistance of value 10 Ω is connected in series with the armature, is __________. (round off to nearest integer)
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 63
Open questionEENAT2 marksNeeds review
A 4-pole induction motor with inertia of 0.1 kg-m² drives a constant load torque of 2 Nm. The speed of the motor is increased linearly from 1000 rpm to 1500 rpm in 4 seconds as shown in the figure below. Neglect losses in the motor. The energy, in joules, consumed by the motor during the speed change is __________. (round off to nearest integer)
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 64
Open questionEENAT2 marksNeeds review
A star-connected 3-phase, 400 V, 50 kVA, 50 Hz synchronous motor has a synchronous reactance of 1 ohm per phase with negligible armature resistance. The shaft load on the motor is 10 kW while the power factor is 0.8 leading. The loss in the motor is 2 kW. The magnitude of the per phase excitation emf of the motor, in volts, is __________. (round off to nearest integer).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 65
Open questionEENAT2 marksNeeds review
A 3-phase, 415 V, 4-pole, 50 Hz induction motor draws 5 times the rated current at rated voltage at starting. It is required to bring down the starting current from the supply to 2 times of the rated current using a 3-phase autotransformer. If the magnetizing impedance of the induction motor and no load current of the autotransformer is neglected, then the transformation ratio of the autotransformer is given by ____________. (round off to two decimal places).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 8
Open questionEEMCQ1 markNeeds review
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
Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 18
Open questionEENAT1 markNeeds review
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 ________%.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 19
Open questionEENAT1 markNeeds review
An alternator with internal voltage of
p.u. and synchronous reactance of 0.4 p.u is connected by a transmission line of reactance 0.1 p.u to a synchronous motor having synchronous reactance 0.35 p.u and internal voltage of
p.u. If the real power supplied by the alternator is 0.866 p.u, then
is ____ degrees. (Round off to 2 decimal places.) (Machines are of non-salient type. Neglect resistances.)Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 33
Open questionEEMCQ2 marksNeeds review
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
Your answerChoose one option.
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