Electrical Machines
To achieve spark less commutation brushes of DC generator are rocked ahead so as to bring them

None of these
 just ahead of magnetic neutral axis.
 in magnetic neutral axis.
 just behind the magnetic neutral axis.

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Electrical Machines
Consider the following statements regarding the magnetization characteristics of a dc generator : 1. It represents the variation of field flux with field current. 2. Variation of open-circuit terminal voltage with field current is independent of speed 3. It is non-linear from zero to rated field current 4. It helps to determine the critical field resistance at a given speed 5. It always starts from the origin Which of these statements are correct ?

 2, 3 and 4
 1 and 4
 1, 2 and 5
 3 and 5

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Electrical Machines
In a star - delta starting of an IM

  line voltage is 57.7 % of stator voltage.
  reduced voltage is applied to the stator.
  applied voltage per stator phase is 57.7 % of a line volt
  resistance is inserted in the rotor.

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