81. Armature reaction mmf and leakage reactance of a synchronous machine are determined by
- open-circuit and short-circuit tests
- open-circuit and zero power factor tests
- open-circuit test only
- zero power factor test only
82. Which one of the following methods would give higher than actual value of regulation of an alternator?
- ZPF method
- MMF method
- EMF method
- ASA method
83. Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator?
- MMF Method
- Synchronous Impedance method
- Potier triangle method
- ASA method
84. Slip test is performed to determine
- slip
- direct-axis reactance and quadrature-axis reactance
- positive sequence reactance and negative sequence reactance
- sub-transient reactance
85. For maximum current during slip test on a synchronous machine, the armature mmf aligns along
- d-axis
- q-axis
- 45 degrees to d-axis
- 45 degrees to q-axis
86. In which one of the following is reluctance power developed?
- salient pole alternator
- non-salient pole alternator
- squirrel cage induction motor
- transformer
87. Which is the value of load angle when the power output of a salient pole synchronous generator is maximum?
- 0 degree
- 45 degree
- 90 degree
- none of the above
88. Higher synchronous reactance is preferred in the present day alternators, because one can have
- reduced sub-transient currents
- reduced harmonic currents
- reduced transient currents
- higher voltage regulation with load
89. When a 3-phase alternator is suddenly short-circuited at its terminals, the initial value of short-circuit current is limited by which one of the following
- subtransient reactance
- transient reactance
- synchronous reactance
- Sum of all the above
90. An alternator with higher value of Short Circuit Ratio has
- poor voltage regulation and lower stability limit
- better voltage regulation and higher stability limit
- poor voltage regulation and higher stability limit
- better voltage regulation and low stability limit