In this article, we shared the alternator objective questions and answers for electrical and electronics engineers.
The below list provides all the multiple-choice questions related to the electrical alternators.
Answers are available at the bottom of the article.
1. If the voltage of one of the two machines running in synchronism is suddenly increased
2. What is the largest size of alternator being manufactured in India?
3. In air-crafts, alternators have an operating frequency of
4. An alternator running in parallel with other alternators all having automatic voltage regulators is to be taken off the bus. The usual procedure before opening the switch is to
5. Salient pole type rotors as compared to cylindrical pole type are
6. Which of the following is a prime mover?
7. As the load power factor of an alternator becomes more leading, the value of generated voltage required to give rated terminal voltage
8. In a cylindrical rotor how much portion of the rotor is wound?
9. Harmonic component of generated e.m.f. will be more in
10. Salient pole rotors are used where
11. 4 pole 1500 r.p.m. alternator will generate e.m.f. at
12. An exciter for a generator is a
13. The load between two steam-driven alternators operating in parallel may be adjusted by varying
14. An infinite bus bar has
15. In a large generator, dampers
16. The Poter’s triangle separates the
17. Unlike D.C. generator kW rating, alternators are rated in
18. Which of the following is not an integral part of the synchronous generator system?
19. In a synchronous machine, all of the following losses are fixed except
20. The regulation of an alternator is likely to be negative in the case of
21. For parallel operation, A.C. polyphase alternators must have the same
22. The slip rings employed in a 3-phase alternator in the hydro station are insulated for
23. When an alternator is supplying unity power factor load, the armature reaction will produce
24. Hydrogen is used in large alternators mainly to
25. Alternators, nowadays, are designed to have poor regulation because
26. Two alternators ‘1’ and ‘2’ are share an inductive load equally. If the excitation of alternator ‘1’ is increased
27. What kind of rotor is most suitable for turbo-alternators that are designed to run at high speed?
28. Which fractional pitch will eliminate the seventh harmonic from the voltage waveform of an alternator?
29. An alternator operating at a lower voltage, for the same power rating, will be
30. In an alternator terminal voltage rise will be more
31. Alternators are usually designed to generate
32. For the alternators operating in parallel, if the load shared by one of them is to be increased, its field excitation is
33. The regulation of an alternator is
34. Which of the following prime-movers is the Ieast efficient?
35. Dirt accumulation in generators can cause all of the following except
36. In a star connected armature winding
37. In a larger generator dampers
38. Due to which of the following- reasons concentrated windings are not used in alternators?
39. If the space flux distribution is nonsinusoidal, e.m.f. induced in the distributed winding
40. Zero power factor method for an alternator is generally used to determine
41. Synchronous impedance method gives more regulation as compared to ampere turn method because
42. An exciter is nothing but a
43. In an alternator, the pitch factor is the ratio of the e.m.fs. of
44. The power factor of an alternator is determined by its
45. If the input to the prime mover of an alternator is kept constant but the excitation is increased, then
46. In an alternator zero power factor method is used to find the
47. The permissible duration for which a generator of rated frequency 50 Hz can run at 46 Hz is
48. A commercial alternator has
49. Where the terminal voltage of an alternator falls on the throwing off the load, it indicates that the load is purely
50. In a synchronous machine, if the field flux axis is ahead of the armature field axis, in the direction of rotation, the machine is working as
51. If the input to the prime mover of an alternator is kept constant but the excitation is changed then
52. Generated e.m.f. for same field current and double speed will be
53. The speed of a 4-pole 60 Hz synchronous machine will be
54. Which harmonic will be totally eliminated in an alternator by using a fractional pitch of 4/5?
55. Large-diameter salient-pole rotors have short axial length mainly because
56. Alternator of a central power station will have
57. Two alternators are to be put in parallel. Which of the following factors should be identical for both?
58. A lower voltage alternator, for the same power rating, will be
59. Fleming’s left-hand rule may be applied to an electric generator to find out the direction of
60. For a 3-phase winding with 5 slots per pole per phase and with a coil span of 12 slot pitch, the value of pitch factor is
61. In an alternator one of the advantages of distributing the winding is to
62. The fictitious part of synchronous reactance takes care of
63. Turbo-alternators usually have
64. When the speed of an alternator increases
65. The frequency of voltage generated in large alternators is
66. The maximum current that can be supplied by an alternator depends on
67. The power drawn by the prime-mover of an alternator, under no-load conditions, goes to
68. When a three-phase alternator supplies capacitive load, armature reaction flux will be
69. Regulation of an alternator supplying resistive or inductive load is
70. If the driving power from the prime mover driving an alternator is lost but the alternator remains connected to the supply network and field supply is on, then the alternator will
71. Regulation of an alternator supplying leading load is
72. In an alternator the armature reaction is mainly influenced by
73. An alternator is capable of delivering power at a particular efficiency. The frequency can be increased by
74. The advantage of salient poles in an alternator is
75. In the case of turbo-alternators the rotor is usually made of
76. The number of poles in turbo-alternator is usually
77. Modern 3-phase alternator of a central power station will have generated voltage of
78. In turbo-alternators, smooth cylindrical type rotors used have long axial lengths because
79. In an alternator, for a coil having a span of 2/3 of pole pitch, the coil span factor will be
80. In an alternator, armature reaction is considered equivalent to
81. Leakage reactance of the armature of a salient pole synchronous machine which varies with the position of the rotor is due to
82. Dirt accumulation in generators can cause
83. Due to which of the following reasons, for aircraft alternators high frequency is used?
84. In power generating stations (Thermal stations), the usual number of poles employed in alternators are
85. Which of the following organizations is engaged in the manufacture of large size alternators for power plants in India?
86. Which of the following methods is best for finding the voltage regulation?
87. An alternator driven by a Francis hydraulic turbine is a ____alternator
88. Which of the following relays come into operation in the event of the failure of the prime-mover connected to the generator?
89. When two alternators are running in exact synchronism, the scychronising power will be
90. In order to reduce the harmonics in the e.m.f. generated in an alternator
91. Which of the following coils in an alternator will have e.m.f. closer to sine waveform?
92. A stationary alternator should not be connected to a live bus-bar because it
93. The rotor preferred for alternators applied to hydraulic turbines are
94. Salient pole type alternators are generally used on
95. The dark and bright lamp method is used for
96. Turbo-alternators are generally used to run at
97. Turbo-rotor is made up of
98. In an alternator short-circuit current is limited by
99. Which of the following conditions does not have to be met by alternators working in parallel?
100. One of the super-thermal power stations is being located at,
101. In which coil the harmonic component of the generated e.m.f. will be more?
102. For parallel operation of the two alternators, the desirable feature is that both should have
103. In an alternator, the armature reaction will be completely magnetizing in case the load power factor is
104. In an alternator, the frequency of voltage generated depends on
105. Excessive windage loss and noise occur with
106. Non-salient pole type of rotor construction is usually provided in the alternators used in
107. In an alternator, the flux is created by the armature m.m.f. subtracts directly from the main flux for the following conditions of the load
108. In an alternator, the stator frame serves
109. If an alternator is operating at leading power factor, then it can be concluded that
110. The synchronous impedance method of finding voltage regulation of an alternator is called the pessimistic method because
111. Unbalanced three-phase stator currents cause
112. The speed of a salient pole machine is nearly
113. For a given output steam turbo-alternators are much smaller in size than water turbine alternators because
114. When two alternators are running in parallel, their kVAR load share and kW load share are changed by changing their
115. If two alternators are running in proper synchronism and the voltage of one machine is suddenly increased
116. An alternator coupled to which prime mover will usually have the highest rotating speed?
117. Damper winding on alternator results in all of the following except
118. To obtain sinusoidal flux distribution
119. ___ plays an important role in overspeed protection of a generator?
120. In alternators, the standard practice nowadays is to have
121. The distribution factor, in alternators, is defined as the ratio of e.m.fs. Of
122. Voltage regulation obtained by synchronous impedance method is
123. Two alternators are running in parallel. If the field of one of the alternators is adjusted it will
124. The power factor of an alternator is determined by its
125. In an alternator, when the load power factor is unity
126. In an alternator field, the effect of cross magnetization is to make the output
127. Three-phase alternators are invariably star-connected because
128. Which of the following prime mover is least efficient?
129. At leading power factor, the armature flux in an alternator
130. An alternator is said to be over-excited when it is operating at
131. If the driving force of both the alternators running in parallel is changed, this will result in a change in
132. The speed of an alternator is changed from 3000 r.p.m. to 1500 r.p.m. The generated e.m.f./phase will become
133. Which of the following is the common synchronous speed in r.p.m. between 50 Hz and be 60 Hz alternators?
134. If two alternators are running in parallel and the excitation of one of the alternators is increased, then
135. If the steam supply of an alternator running in parallel with another identical alternator is increased keeping its excitation constant, then
136. The choice of field construction, in an alternator, is basically determined by
If you liked this article, then please subscribe to our YouTube Channel for Electrical, Electronics, Instrumentation, PLC, and SCADA video tutorials.
You can also follow us on Facebook and Twitter to receive daily updates.
