SRM University 2007 B.Tech Electronics and Communications Engineering BANK - Question Paper

47. What are the different kinds of speed control for series motor?

UNIT – II TRANSFORMERS
48. What is a transformer?
49. Give the working principle of transformer
50. Define voltage transformation ratio.
51. Give the emf formula of the transformer.
52. What are the different kinds of stampings used for construction of core of a transformer?
53. What is the material used for making transformer core? Why?
54. What are the different losses in a transformer?
55. Classify transformers.
56. What is an ideal transformer?
57. What are magnetizing and working component currents?
58. What is the function performed by the primary current under no load condition?
59. A 1F 50KVA transformer has primary voltage of 6600V and a secondary voltage of 254V. It has 32 turns on secondary. compute the primary turns.
60. A 40KVA, 3300/240V, 50Hz 1F transformer has 600 turns on primary. Determine the maximum values of flux in the core.
61. A transformer is never given with DC supply. Why?
62. What is eddy current? How can it be minimize in a transformer?
63. Define turns ratio with respect of a transformer.
64. Draw the phasor diagram for an ideal transformer under no load condition.
65. Draw the phasor diagram for a practical transformer under no load condition.
66. What is the significance of increase in primary current of a transformer, when the secondary is loaded?

THREE PHASE INDUCTION MOTOR

67. Classify AC motors.
68. Why is an induction motor called so?
69. What are the advantages of induction motors over other motors?
70. What are the disadvantages of induction motors over the other motors?
71. How can the induction motors be classified, based on the construction of rotor?
72. State the working principle of 3F induction motor.
73. What is synchronous speed?
74. Why does the rotor of a 3F inductor motor rotate?
75. Define slip.
76. Give the expression for frequency of rotor current.
77. Give an expression for torque developed in the induction motor.
78. What are the advantages of slip ring Induction motor over the squirrel caged motor?
79. Give an expression for starting torque of IM.
80. What is the condition for maximum starting torque in an IM?
81. What is the effect of change in supply voltage, on the working of IM?
82. Give 4 applications of induction motor.
83. Give the condition for maximum torque under running conditions.
84. Draw the torque – slip characteristic of an induction motor.
85. What are the starting methods available for IM?

Earning:   Approval pending.