Related Questions

In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
A the motor is said to be fully loaded
B the torque generated is maximum
C the excitation is said to be zero per cent
D the excitation is said to be hundred per cent
An over excited synchronous motor on noload is known as
A synchronous condenser
B generator
C induction motor
D alternator
A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
A remain same
B go down
C improve
D none of the above
In an actual transformer the iron loss remains practically constant from noload to fullload because
A value of transformation ratio remains constant
B permeability of transformer core remains constant
C core flux remains practically constant
D primary voltage remains constant
A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
A Slop speed operation
B High starting torque
C Low windage losses
D All of the above
A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
A synchronous motor has no slip
B stator supply is not required to produce magnetic field
C mechanical load on the rotor remains constant
D synchronous motor has large airgap
The power factor of a synchronous motor is better than that of induction motor because
A stator supply is relieved of responsibility of producing magnetic field
B mechanical load on the motor can be adjusted
C synchronous motor runs at synchronous speed
D synchronous motor has large air gap
The low power factor of induction motor is due to
A Rotor leakage reactance
B Stator reactance
C The reactive lagging magnetizing current necessary to generate the magnetic flux
D All of the above
The good power factor of an induction motor can be achieved if the average flux density in the air gap is
A Absent
B Small
C Large
D Infinity
The power factor of a single-phase induction motor is usually
A lagging
B always leading
C unity
D unity to 0.8 leading

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