The synchronous motor is not inherently self-starting because

A the force required to accelerate the rotor to the synchronous speed in an instant is absent
B the starting device to accelerate the rotor to near synchronous speed is absent
C a rotating magnetic field does not have enough poles
D the rotating magnetic field is produced by only 50 Hz frequency currents

Correct Answer: the force required to accelerate the rotor to the synchronous speed in an instant is absent

Bissoy MCQ
#Electrical Engineering #Synchronous Motors

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
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
As the load is applied to a synchronous motor, the motor takes more armature current because
A The increased load has to take more current
B The rotor by shifting its phase backward causes motor to take more current
C The back e.m.f. decreases causing an increase in motor current
D The rotor strengthens the rotating field causing more motor current
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
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
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
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will
A stop
B run as induction motor
C function as static condenser
D burn with dense smoke
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
A induction motor torque in field winding
B induction motor torque in damper winding
C eddy current and hysteresis torque in pole faces
D reHetance motor torque due to saliency of the rotor
E all of the above methods

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