1
GATE EE 2021
MCQ (Single Correct Answer)
+1
-0.33

$$ \text { Consider the table given : } $$

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

A

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

B

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

C

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

D

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

2
GATE EE 2021
Numerical
+2
-0

An 8 pole, $50 \mathrm{~Hz}, 3$ phase, slip-ring induction motor has an effective rotor resistance of $0.08 \Omega$ 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 $\_\_\_\_$ $\Omega$. (Round off to 2 decimal places). Negleet magnetizing eurrent and stater leakage impedanee. Consider equivalent eireuit parameters referred to stator.

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3
GATE EE 2021
Numerical
+1
-0

The power input to a $500 \mathrm{~V}, 50 \mathrm{~Hz}, 6$ pole, 3 phase induction motor running at 975 rpm is 40 kW . The stator losses are 1 kW . If the total friction and windage losses are 2.025 kW , then the efficiency is

$\_\_\_\_$ $\%$.

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4
GATE EE 2021
Numerical
+2
-0

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 $0.025 \Omega$, field resistance is $50 \Omega$ and brush drop is 2 V . Ignoring armature reaction, the speed of the motor is _________ rpm. (Round off to 2 decimal places.)

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