1
GATE EE 2023
MCQ (Single Correct Answer)
+1
-0.33

A 10-pole, 50 Hz, 240 V, single phase induction motor runs at 540 RPM while driving rated load. The frequency of induced rotor currents due to backward field is

A
100 Hz
B
95 Hz
C
10 Hz
D
5 Hz
2
GATE EE 2023
MCQ (Single Correct Answer)
+1
-0.33

The four stator conductors (A, A', B and B') of a rotating machine are carrying DC currents of the same value, the directions of which are shown in the figure (i). The rotor coils $$a$$-$$a'$$ and $$b$$-$$b'$$ are formed by connecting the back ends of conductors '$$a$$' and '$$a'$$' and '$$b$$' and '$$b'$$', respectively, as shown in figure (ii). The e.m.f. induced in coil $$a$$-$$a'$$ and coil $$b$$-$$b'$$ are denoted by $${E_{a - a'}}$$ and $${E_{b - b'}}$$, respectively. If the rotor is rotated at uniform angular speed $$\omega$$ rad/s in the clockwise direction then which of the following correctly describes the $${E_{a - a'}}$$ and $${E_{b - b'}}$$?

GATE EE 2023 Electrical Machines - D.C Machines Question 2 English

A
$${E_{a - a'}}$$ and $${E_{b - b'}}$$ have finite magnitudes and are in the same phase
B
$${E_{a - a'}}$$ and $${E_{b - b'}}$$ have finite magnitudes with $${E_{b - b'}}$$ leading $${E_{a - a'}}$$
C
$${E_{a - a'}}$$ and $${E_{b - b'}}$$ have finite magnitudes with $${E_{a - a'}}$$ leading $${E_{b - b'}}$$
D
$${E_{a - a'}}$$ = $${E_{b - b'}}$$ = 0
3
GATE EE 2023
Numerical
+1
-0.33

A separately excited DC motor rated 400 V, 15 A, 1500 RPM drives a constant torque load at rated speed operating from 400 V DC supply drawing rated current. The armature resistance is 1.2 $$\Omega$$. If the supply voltage drops by 10% with field current unaltered then the resultant speed of the motor in RPM is ____________ (Round off to the nearest integer).

Your input ____
4
GATE EE 2023
Numerical
+2
-0.67

A three-phase synchronous motor with synchronous impedance of 0.1+j0.3 per unit per phase has a static stability limit of 2.5 per unit. The corresponding excitation voltage in per unit is _________ (Round off to 2 decimal places).

Your input ____
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