Load On Synchronous Motor Multiple Choice Questions and Answers

31. 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 but armature current will increase

32. As the load is applied to 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

33. The standard full-load power factor ratings for synchronous motors are

   A.Zero or 0.8 leading

   B.Unity or 0.8 lagging

   C.Unity or 0.8 leading

   D.Unity or zero

34. A synchronous motor connected to infinite bus-bars has at constant full-load, 100% excitation and unity p.f. on changing the excitation only, the armature current will have

   A.Leading p.f. with under-excitation

   B.Leading p.f. with over-excitation

   C.Lagging p.f. with over-excitation

   D.No change of p.f.

35. When load on an over-excited or under-excited synchronous motor is increased, rate of change of its armature current as compared with that of power factor is

   A.More

   B.Less

   C.Equal

   D.Twice

< 1 2 3 4 5 6 7 8 9 10 Next>