The ferrite cores are used for ____________ transformers.
a) Small transformers
b) Medium transformers
c) Large transformers
d) Medium and small transformers
Q.2.
A 2-pole, 3-phase,Hz induction motor is operating at a speed ofrpm. The frequency of the rotor current of the motor in Hz is __________
a) 43.33
b) 42.54
c) 43.11
d) 41.47
Q.3.
Calculate the phase angle of the sinusoidal waveform w(t)=.45sin(87πt+8π÷787).
a) 2π÷39
b) 8π÷787
c) 5π÷74
d) 42π÷4
Q.4.
Calculate the moment of inertia of the disc having a mass of 1 kg and radius of 1 m.
a) 1 kgm2
b) .5 kgm2
c) 2 kgm2
d) 3 kgm2
Q.5.
Calculate the moment of inertia of the thin spherical shell having a mass of 3 kg and diameter of 6 cm.
a) .0178 kgm2
b) .0147 kgm2
c) .0398 kgm2
d) .0144 kgm2
Q.6.
The power factor of a synchronous motor __________
a) Improves with an increase in excitation and may even become leading at high excitations
b) Decreases with increase in excitation
c) Is independent of its excitation
d) Increase with loading for a given excitation
Q.7.
The frame of a synchronous motor is made of _________
a) Aluminum
b) Silicon steel
c) Cast iron
d) Stainless steel
Q.8.
The slope of the V-I curve is 45°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
a) 2 Ω
b) 3 Ω
c) 4 Ω
d) 1 Ω
Q.9.
Which one of the following methods would give a higher than the actual value of regulation of the alternator.
a) ZPF method
b) MMF method
c) EMF method
d) ASA method
Q.10.
A 3-phase induction motor runs at almostrpm at no load andrpm at full load when supplied with power from aHz, 3-phase supply. What is the corresponding speed of the rotor field with respect to the rotor?
a) 430 revolution per minute
b) 440 revolution per minute
c) 460 revolution per minute
d) 450 revolution per minute
Q.11.
Which of the following core has linear characteristics?
a) Air core
b) Steel core
c) CRGO core
d) Iron core
Q.12.
Calculate the active power in a 1 Ω resistor with 2 A current flowing through it.
a) 2 W
b) 4 W
c) 7 W
d) 1 W
Q.13.
The slope of the V-I curve is 13°. Calculate the value of resistance. Assume the relationship between voltage and current is a straight line.
a) .2544 Ω
b) .7771 Ω
c) .2308 Ω
d) .5788 Ω
Q.14.
A 2-pole lap wound generator witharmature conductors and a flux per pole of .Wb has an armature current ofA. The developed torque is _________
a) 39.7 N-m
b) 39.2 N-m
c) 38.4 N-m
d) 37.2 N-m
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