MCQ – DC Machines
#1. A DC generator works on the principle of....?
incorrect#2. The process by which an emf induced in a DC generator is called.......?
incorrect
#3. The direction of dynamically induced emf in DC generator can be identified by rule of.....?
#4. The yoke of a dc machine made of....?
#5. The armature of dc machine is made by....?
#6. The thickness of laminations of pole core varies from....?
#7. The armature core is laminated to minimise the....?
#8. Carbon brushes are used in dc machine because of....?
incorrect
welding generator used metal graphite brushes.
#9. The material used for commutator is....?
incorrect
#10. In small capacity dc machines the yoke is made up of....?
#11. The material used for split ring is....?
#12. The number of parallel path in the wave winding of a dc machine is....?
#13. The number of parallel path in a lap winding dc machine is....?
#14. A lap winding is made in a machine for....?
#15. High voltage dc machines use which winding?
#16. In a 4 pole lap wound dc machine the resistance of one conductor is 0.2 ohm of 64 conductors.calculate the armature resistance?
incorrect
conductors/parallel path= 64/4=16
resistance/parallel path=16×0.2=3.2ohm
total armature resistance for 4 parallel path= 3.2/4=0.8 ohm
#17. Slot wedges in a dc machine are made of....?
#18. An exciter for a turbo generator is ....?
#19. The commutator of a dc generator act as....?
#20. Flemmings right hand rule applicable to....?
#21. A dc series motor is most suitable for....?
#22. In which type of DC motor, two point starter is used?
#23. Which type of DC generator is used for battery charging?
#24. Two dc series motors are connected in series to produce a torque T. now if the motors are connected in parallel, the torque produced will be....?
#25. For traction which motor is used.....?
#26. Which motor has widest variety of methods of speed control?
#27. Interpoles are used for.....?
#28. No load speed of dc series motor is......?
#29. The condition for a maximum power output from a dc motor is Eb=.....?
#30. In swinburns method of testing dc machines. the shunt motor is run as a.....?
#31. Poles of dc machine are often laminated to.....?
#32. The armature of dc machine is made of silicon steel laminations to ....?
#33. The teeth of the armature of dc machine are skewed is to reduce.......?
#34. The commutator of dc motor serves the purpose of.....?
#35. In dc machines armature windings are placed on the rotor because of the necessity for....?
#36. A lap wound dc machine has 800 conductors and 12 poles. The voltage induced per conductor is 2V. The machine generates a voltage of.....?
#37. Th brushes of a dc machine should be physically placed on the....?
#38. The highest speed attained by dc shunt motor is....?
#39. The direction of rotation of shunt motor can be reversed by inter changing....?
#40. Which of the following motor can work satisfactorily on both AC & DC?
#41. Eddy current of the ferromagnetic core is propotional to.....?
#42. Which motor should not be used for centrifugal pump?
#43. The speed of the DC motorcan be controlled by....?
#44. The core losses in a dc machine occures in.....?
#45. The speed of dc series motor at no load is....?
#46. DC shunt motor is a .....?
#47. DC series motor is a .....?
#48. If a dc motor is connected to ac supply, it will....?
#49. Four point starter can be used for.....?
#50. Which of the following motor has poorest speed regulation?
#51. The magnitude of the back emf depends on....?
#52. A shunt motor can be started with....?
#53. Compensating winding of dc motor is connected in......?
#54. If the field of the shunt motor is opened....?
#55. A DOL starter is used for starting motors...?
#56. DC shunt motor is used for driving....?
#57. The commutator in a dc machine acts as....?
#58. Th purpose of dummy coils in the dc machine is to ....?
#59. Functions of interpoles in a dc machine is to....?
#60. As the load incresed the speed of a shunt motor ......?
#61. Commutator segments of dc machine by....?
#62. For a 4 pole dc machine with wave wound armature, the number of brushes required is....?
#63. The material used for split rings is...?
#64. The split rings are connected to facilitate the output will be....?
#65. Armature resistance of a dc machine generally....?
#66. In a 6 pole simplex lap wound armature, the number of parallel paths are...?
#67. As the speed of dc generator increase, the induced voltage will......?
#68. Shunt field resistance value for building up voltage should be....?
#69. The current drawn by a dc motor at starting is...?
#70. Plugging of dc machine is normally executed by....?
#71. Nature of induced current in the dc generator is....?
#72. Steinmetz formula is related to....?
#73. The critical resistance of a dc generator is the resistance of.....?
#74. The wave winding is suitable for......voltage and ......current dc generators?
#75. In dc machines the armature winding must be....?
#76. Which type of dc generators do not need equilizers for satisfactory parallel operation?
#77. Which of the following generator has poorest voltage regulation?
#78. Differential compound generators are suitable for....?
#79. Stray losses are....?
#80. A compound motor is best suited for driving......?
#81. For a dc shunt motor, which method is used for wide and very sensitive speed control?
#82. Which of the motor is not self starting?
#83. If series winding is connected in series with the armature and then the shunt winding is connected parallel to the combination, then such a combination will form which kind of gnerator?
#84. The basic difference in 4 point starter when compared to 3 point starter is.....?
#85. Which of the following starter used in dc series motor?
#86. Which of the following starter used in dc shunt motor?
#87. Which of the following starter used in dc compound motor?
#88. The number of parallel paths in a simplex 8 pole lap wound armature in a dc generator is...?
#89. ....... are loops of electric current induced within conductors by changing magnetic field?
#90. In a dc motot back emf is directly propotional to.....?
#91. Function of inter poles used in dc machine is to.....?
#92. The method of speed control of series motor used in electric trains is.....?
#93. The dc generator used for arc welding process is......?
#94. Interpoles in dc machine used to....?
#95. In dc generator armature reaaction is produced by?
#96. According to which law, the back emf in DC motor opposes the applied voltage?
#97. A triplex wave winding have .... parallel path?
#98. The open circuit characteristics of a DC generator is also called its ..... characteristics?
#99. Which of the following is a loss in DC generator?
#100. The compensating windings are connected in ..... of a DC generator?
#101. Hysteresis loss is proportional to....?
#102. The critical field resistance of a shunt generator should be....?
#103. The most suitable material for cores of electromagnet is....?
#104. The direction of induced emf can be determined by....?
#105. Motor used in the household refrigerator is.....?
#106. Which motor would you select for vaccum cleaner?
#107. The voltage regulation of an over compound dc generator is always...?
#108. The normal value of armature resistance of a dc motor is…?
#109. The speed of dc motor inversely its...?
#110. Which test used for find stray losses of DC shunt motor?
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