Electrical Machines
Consider the following statements regarding dc machines : 1. possible resistance of shunt-field winding is 1 Ω 2. possible resistance of series-field winding is 1 Ω 3. electrographite brushes are used for 230 V, 10 A machines 4. Copper-graphite brushes are used for 230 V, 10 A machines 5. Possible armature-circuit resistance is 1 Ω From these, the correct statements are

 1, 3, 5
 1, 4
 2, 4 ,5
 2, 3 , 5

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Electrical Machines
Torque angle of a synchorous machine operating from a constant voltage bus is usually defined as the space angle between

 Stator mmf wave and resultant flux density.
  Rotor mmf wave and stator mmf wave.
 Rotor mmf wave and resultant flux density wave.
 Stator mmf wave and resultant mmf wave.

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Electrical Machines
An alternator is feeding an infinite busbar. Its prime mover is suddenly shutdown. The alternator will

 continue to work as alternator but the direction of rotation will reverse.
 continue to work as synchronous motor with same direction of rotation.
 come to stand still.
 start working as induction motor.

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