synchronous alternator, which of the following coils will have emf closer to
sine waveform ?
(A) concentrated winding in full pitch coils
(B) concentrated winding in short pitch coils
winding in full pitch coils
(D) distributed winding in short pitch coils.
alternator has rated field current of 4 A. The alternator develops 180 V while
drawing a field current of 2 A at 750 rpm. If the field current is made 4 A at
750 rpm generated voltage could be
(A) 400 V
armature reaction of an alternator will be completely magnetizing in case the
load power factor is
(C) zero lagging
(D) zero leading.
of the following is not an integral part of synchronous generator system ?
(A) prime mover
(B) distribution transformer
(C) excitation system
(D) protection system.
turbo generators the range of excitation voltage is
(A) 10 to 20 V
(B) 30 to 100 V
(C) 100 to 800 V
(D) 1000 to 1800 V.
case of low speed hydrogenerators, the short circuit ratio is usually
(A) 0.1 to 0.5
(B) 0.5 to 0.6
(C) 0.6 to 1.0
(D) 1.0 to 1.5.
permissible duration for which a generator of rated frequency 50 Hz can run at
46 Hz is
(D) one minute.
permissible duration in supply . frequency is
(A) ± 2 %
± 5 %
(C) ± 10 %
± 25 %.
regulation of an alternator is likely to be negative in case of
(A) high speed alternators
(B) slow speed alternators
(C) lagging power factor of the load
(D) leading power factor of the load.
Questions 85 to 88 refer to the data given below:
A phase, 50 Hz, 6600 V,
alternator is rated at 6600 kW at 0.8 power factor and a full load efficiency
85. kVA is rating of the alternator is
(A) 750 kVA
(B) 7500 kVA
(C) 75000 kVA
(D) 750000 kVA.
current rating of the alternator is
(A) 65.63 A
(C) 6563 A
(D) 65630 A.
input to the alternator is
(A) 666.6 kW
88. If the input. to an alternator remains
unaltered, but excitation is changed then which of the following will not
(A) kVA output
(B) kW output
(D) all of the above.
of the following method is likely to give the voltage regulation more than the
actual value ?
(A) Synchronous reactance method
(B) MMF method
(C) Zero power factor method
(D) None of the above.
effect of cross magnetization in an alternator field is to make the output
(A) true sinusoidal
(C) harmonic free
(D) none of the above.