Related Questions

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 a synchronous motor, the magnitude of stator back e.m.f. Eb depends on
A load on the motor
B d.c. excitation only
C both the speed and rotor flux
D none of the above
The back e.m.f. in the stator of a synchronous motor depends on
A number of poles
B flux density
C rotor speed
D rotor excitation
A synchronous motor can be used as a synchronous capacitor when it is
A under-loaded
B over-loaded
C under-excited
D over-excited
A synchronous motor can develop synchronous torque
A when under loaded
B while over-excited
C only at synchronous speed
D below or above synchronous speed
In a synchronous motor, the maximum power developed depends on all of the following except
A rotor excitation
B maximum value of coupling angle
C direction of rotation
D supply voltage
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
While starting a synchronous motor by induction motor action, field winding is usually
A connected to D.C. supply
B short-circuited by low resistance
C kept open-circuited
D none of the above
A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
A power factor as well as armature current will decrease
B power factor as well as armature current will increase
C power factor will increase but armature current will decrease
D power factor will decrease and armature current will increase
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

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