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

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Electrical Machines
If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

 Pe will increase but Ph will decrease
 Ph will increase but Pe will decrease
 Ph will decrease but Pe will remain same
 both hysteresis loss(Ph) and eddy current loss(Pe) will increase

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