## electrician

### MCQ ON SYNCHRONOUS MOTOR PAGE - 2

1.
 While running a synchronous motor is compelled to run at synchronous speed because of A Damper winding in  its pole faces B Magnetic locking between stator and rotor poles C Induced em.f in rotor field winding by stator flux D Compulsion due to Lenz’s law Answer : B Explanation :
2.
 In a synchronous motor, the magnitude of stator back e.m.f Eb depends on A Speed of the motor B Load on the motor C Both the speed and rotor flux D D.C excitation only Answer : D Explanation :
3.
 The V-curves of a synchronous motor show relationship between A Excitation current and back e.m.f B Field current and power factor C D.C field current and A.C armature current D Armature current and supply voltage Answer : C Explanation :
4.
 When running under no load condition and with normal excitation armature current La drawn by a synchronous motor A Leads the back e.m.f  Eb by a small angle B Is large C Lags the applied voltage V by a small angle D Lags the resultant voltage Er by 900 Answer : C Explanation :
5.
 A synchronous motor running with normal excitation adjusts to load increases essentially by increases in its A Power factor B Torque angle C Back E.M.F D Armature current Answer : D Explanation :
6.
 The angle between the synchronously rotating stator flux and rotor poles of a synchronous motor is called …. angle. A Synchronizing B Torque C Power factor D Slip Answer : D Explanation :
7.
 A synchronous motor is stated n: A Lagging power factor only B Leading power factor only C Both types of power factors i.e. lagging and leading D None of the above Answer : C Explanation :
8.
 The motor whose rotor and rotating magnetic field of the stator rotate at the same speed is called A induction motor B slip ring induction motor C synchronous motor D universal motor Answer : C Explanation :
9.
 A synchronous motor always works at A Synchronous speed B Lesser than synchronous speed C More than synchronous speed D None of the stated above Answer : A Explanation :
10.
 Which one of the following characteristics is NOT applicable to synchronous motors? A Runs at a constant speed at all loads B Suitable to supply only mechanical load C Can also be used for PF improvement D Not self starting Answer : B Explanation :