61. In an alternator, the armature reaction is considered to be equivalent to a fictitious
- reactance
- resistance
- impedance
- admittance
62. A synchronous generator is feeding a zero power factor(lagging) load at rated current. The armature reaction is
- magnetizing
- demagnetizing
- cross-magnetizing
- ineffective
63. The synchronous reactance is the
- reaction due to armature reaction of the machine
- reactance due to leakage flux
- combined reactance due to leakage flux and armature reaction
- reactance either due to leakage flux and armature reaction
64. Drop in terminal voltage of an alternator due to armature reaction is countered by
- damper winding
- effect of saliency increased
- prime mover output
- automatic voltage regulator
65. The saturated synchronous reactance of an alternator is _______ its unsaturated synchronous reactance.
- more than
- less than
- equal to
- none of these
66. In an alternator, short circuit current is limited by the
- saturated synchronous impedance
- unsaturated synchronous impedance
- either of the above
- none of these
67. When the inductive load is thrown off, the terminal voltage will
- increase
- decrease
- remain unchanged
- none of these
68. As the leading power factor of the load of an alternator decreases, the magnitude of generated voltage required to give rated terminal voltage
- increases
- decreases
- remain unchanged
- none of these
69. The power factor on which an alternator operates depends on the
- speed of the prime mover
- nature of the load being supplied
- armature losses
- copper losses
70. Unbalance three phase stator currents cause
- vibrations
- heating of rotor
- double frequency currents in the rotor
- all of the above