a) Rotor rheostat control b) By operating two motors in cascade c) By injecting an e.m.f. in the rotor circuit d) By changing the number of stator poles Ans: (d)
a) True b) False Ans: (a)
a) The same frequency as the slip frequency b) The same phase as the rotor e.m.f. c) High value for the satisfactory speed control d) Zero frequency Ans: (a)
a) To improve power factor and provide better speed regulation b) To eliminate armature reaction c) To prevent hunting in the motor d) To provide mechanical balance Ans: (a)
a) True b) False Ans: (a)
a) True b) False Ans: (a)
a) Increasing the magnitude of inductances of field and armature winding b) Decreasing the magnitude of reactances and armature winding c) Equalizing the armature resistance to armature reactance d) None of the above Ans: (b)
a) Increasing the number of turns on armature winding proportionately b) Decreasing the number of turns on armature winding c) Increasing armature resistance d) Equalizing the armature resistance to the armature reactance Ans: (a)
a) Connected in parallel with the armature b) Short-circuited and has no interconnection with the motor circuit c) Connected in series with the armature d) None of the above Ans: (c)
a) True b) False Ans: (a)
a) Increasing inductance of the compensating winding b) Increasing resistance of the compensating winding c) Decreasing the number of turns in the compensating winding d) Shunting the winding of each commutating pole with non-inductive resistance Ans: (d)
a) Same output but different speeds b) Same speed and different output c) Approximately same output and same speed d) Synchronous speed Ans: (c)
a) To facilitate commutation and avoid sparking at the brushes b) To reduce the resistance of the armature c) To reduce the resistance of the armature d) To reduce the weight of the armature Ans: (a)
a) A.C. series motor b) Universal motor c) Repulsion motor d) Reluctance motor Ans: (d)
a) D.C. series motor b) A.C. series motor c) Induction motor d) Reluctance motor Ans: (d)