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83 Multiple choice questions

  1. Sleeve or ball bearings.
  2. The type of enclosure.
    generator (open frame) motor (fully enclosed).
  3. So that the strength of the interpole matches the strength of the armature field.
  4. Effective voltage.
  5. Efficiency is the ratio of power out to power in.
  6. Mechanical, electrical, magnetic.
  7. The field coils must be properly connected with respect to the armature and to each other.
  8. As armature current increase, the strength of the series field increase.
  9. Armature current, armature resistance.
  10. Opposes.
  11. Critical field resistance.
  12. Armature reaction is a distortion of the main field flux caused by current flowing in armature conductors.
  13. 0
  14. Base speed.
  15. Field rheostats should be set to their minimum ohmic value.
  16. Fail to start.
  17. Flux per pole ( excitation and rotational speed.
  18. Differential compound.
  19. By laminating the core materials.
  20. The rheostat would have to carry the high armature current resulting in high wattage losses.
  21. Residual magnetism.
  22. No.
  23. Connected load on terminal voltage.
  24. Series windings.
  25. Armature current.
  26. Differential compound.
  27. The current for separately excited fields is obtained from a source external to the machine.
  28. The direction of force acting on a conductor.
  29. Decrease.
  30. Toque and speed.
  31. Armature.
  32. Lap windings are used in high current, low voltage applications.
    Wave windings are used for low current, high voltage applications.
  33. Interpoles.
  34. The impedance of the connected load.
  35. Counter emf.
  36. One and two psi.
  37. No-load terminal voltage.
  38. Weakening of the main field, Exvessive brush sparking.
  39. Reverse the connection of the armature leads. Reverse the connection of both the series and shunt field leads.
  40. Armature = A; Shunt field = F; Series field = S
  41. The persistence of high starting current may damage the motor.
  42. Bearing friction and windage.
  43. Whenever a conductor carries current in the presence of a magnetic field, a force will act on the conductor at right angles to the field.
  44. Decrease.
  45. The commutator maintains the current in one direction to the external circuit.
  46. Interpole coils are connected in series with the armature.
  47. Copper losses.
  48. Armature resistance.
  49. Differential compound.
  50. Flat-compound.
  51. The increase in armature current )due to a decrease in counter emf) is greater than the decrease in excitation.
  52. The generated voltage is reduced by one third.
  53. Carbon, graphite, electro-graphite, and copper graphite.
  54. A small number of turns of large gauge wire.
  55. Open faced ball bearings.
  56. Series and shunt (parallel).
  57. A reduction in terminal voltage with an increasing load. Impaired commutation.
  58. IR drop of the armature, armature reaction and loss of field current due to reduction in generated voltage.
  59. Flux, armature current.
  60. The motor would stall.
  61. Field poles provide the necessary magnetic field.
  62. Cumulative compound.
  63. Magnetos.
  64. Compensating windings.
  65. In long shunt, the shunt field is connected across the line. In short shunt, the shunt field is connected across the armature.
  66. Connect the shunt field across the source of emf.
  67. Flux, speed.
  68. Without a load the circuit is an open circuit so no current flows through the series field coils.
  69. Field rheostat.
  70. A rheostat in the field circuit. (field rheostat)
  71. Both series and shunt.
  72. Speed regulation.
  73. The rising voltage characteristic is used to offset the decrease in terminal voltage associated with shunt field excitation in a compound generator.
  74. Over-compound.
  75. Flashing the field.
  76. Resistance is placed in series with the armature.
  77. Number of poles, flux per pole, rotational speed, number of armature paths, number of active armature conductors.
  78. Torque is a twisting or turning force that is capable of producing rotation about an axis.
  79. The voltage applied to the armature.
  80. Lap and Wave.
  81. Increase.
  82. In a generator, the armature is a source of emf. In a motor, the armature is a load.
  83. Residual magnetism.