Electrical Machines
A slip ring Induction motor runs at 290 rpm at full load, when connected to 50 Hz supply. Determine the number of poles and slip.

  P = 40, s = 5.79 %.
  P = 50, s = 4.43 %.
  P = 20, s = 3.33 %.
  P = 60, s = 0.96 %.

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Electrical Machines
Two of supply terminals to a 3 - Φ induction motor get interchanged during re-connection after normal maintenance. When switched on the supply, the motor will

  not start at all.
  get heated and damaged.
  rotate in the same direction as before maintenance.
  rotate in direction opposite to that before maintenance.

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Electrical Machines
A compound dc generator is delivering full load current at a terminal voltage of 230 V. Its series-field winding gets short circuited. If its terminal voltage 1. becomes more than 230 V, it is overcompounded generator 2. becomes more than 230 V, it is differentially compounded generator 3. becomes less than 230 V, it is overcompounded generator 4. becomes less than 230 V, it is differentially compounded generator 5. becomes less than 230 V, it is level compounded generator From these, the correct answer is

 1, 4, 5
 1, 4
 2, 3, 5
 2,3

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