57.  Zero power factor method for an alternator is generally used to determine
A. synchronous impedance of alternator
B. efficiency of alternator
C. voltage regulation of the alternator
D. none of the above

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58. In an alternator the armature reaction is mainly influenced by
A. the power factor of the load
B. short-circuit ratio
C. speed of the alternator
D. total current drawn

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59.  Regulation of an alternator supplying resistive or inductive load is
A. always negative
B. always positive
C. either of the above
D. none of the above

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60.  4 pole 1500 r.p.m. alternator will generate e.m.f. at
A. 20 Hz
B. 40 Hz
C. 50 Hz
D. 60 Hz

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61. To obtain sinusoidal flux distribution
A. chamfering of poles is done in turboalternators only
B. chamfering of poles is done in salient pole alternators only
C. either of the above
D. none of the above

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62.  In air-crafts, alternators have operating frequency of
A. 800 Hz
B. 400 Hz
C. 60 Hz
D. 50 Hz

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63. Alternators, now a days, are designed to have poor regulation because
A. it reduces the construction cost
B. it limits the value of short circuit current
C. we employ automatic voltage regulators
D. none of the above

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