Synchronous Motors Objectives Part 02

21 . In a synchronous motor if the back emf generated in the armature at no load is approximately equal to applied voltage then excitation is said to be 100%

22 . A synchronous motor is connected to supply voltage V and drawing current I, Resultant of V and back emf Eb is represented by E in the below figure It is concluded that the resultant V and Eb is consumed by synchronous impedance

23 . A 3 phase, 400 V, 50 Hz salient pole synchronous motor is fed from an infinite bus and is running at no load, now if the field current of the motor is reduced to zero the motor will run at synchronous speed

24 . The purpose of embedding the damper winding in the pole face is to eliminate hunting and provide adequate starting torque

25 . Please see no. 14

26 . In case of a synchronous motor, the magnitude of stator back emf depends on DC excitation

27 . Which of the following is non-self-starting Synchronous motor

28 . The back emf in the stator of a synchronous motor depends on rotor excitation

29 . Which motor can conveniently operate on lagging as well as leading power factor Synchronous motor

30 . A synchronous motor working on leading power factor and not driving any machancial, is known Synchronous condenser

31 . The constant speed of synchronous motor can be changed to new fixed value by changing the frequency of supply

32 . A 3 phase 400 V 50 Hz synchronous motor is operating at zero power factor lagging with respect to the excitation voltage. The armature reaction mmf produced by the armature current will be magnetizing

33 . In a synchronous motor, the torque angle is a angle between the rotating stator flux and rotor poles

34 . A 3 phase 400 V, 50 Hz, 4 pole synchronous motor has a load angle of 10o electrical. The equivalent mechanical degrees will be 5 degrees

35 . A 3 phase. 400 V, 50 Hz synchronous motor has fixed excitation. The load on the motor is doubled, the torque angle ꝕ , will nearly become equal to 2ꝕr

36 . The hunting in synchronous motor takes place when load is variable

37 . V curves for synchronous motor represent relation between armature current and field current

38 . The breakdown of torque of a synchronous motor varies as applied voltage

39 . Hunting in synchronous motor cannot be due to winding friction

40 . Please see no. 16