71. Regulations of an alternator supplying resistive or inductive load is
- always positive
- always negative
- either of the above or zero
- none of the above
72. A leading pf load on an alternator implies that its voltage regulation shall be
- positive
- negative
- zero
- any one of these
73. The effect of leading power factor on the voltage regulation of an alternator is
- increasing in nature
- decreasing in nature
- maintained at constant value
- oscillating in nature
74. The leakage reactance of a three phase alternator is determined by performing
- open circuit and zero power factor tests
- zero power factor test and slip test
- open and short circuit tests
- short circuits and slip test
75. The regulation obtained by synchronous impedance method is always higher than actual value because
- synchronous reactance is assumed variable while it is not
- effective armature resistance is assumed constant
- synchronous reactance is assumed constant while it is not
- field current is increased to give short circuit current about twice of full load current
76. The short-circuit characteristic of an alternator is
- always linear
- always non-linear
- either (1) or (2)
- none of these
77. Under short-circuit conditions, the power factor of an alternator is
- unity
- almost zero lagging
- almost zero leading
- none of the above
78. The zero power factor characteristics for the potier diagram can be obtained by loading the alternator using
- lamp load
- synchronous motor
- water load
- dc motor
79. Modern alternators are designed to have poor regulation as it
- increases the value of short-circuit current
- limits the value of short-circuit current
- increases the efficiency of operation
- both (1) and (3)
80. The phasor diagram of ASA method gives
- reliable results for both regulation and power angle of a salient pole synchronous generator.
- reliable result for power angle but erroneous result for regulation.
- reliable result for regulation but erroneous result for power angle.
- erroneous results for both regulation and power angle of a salient-pole synchronous generator.