Electrical Machines
In a 3 - Φ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by

  E1 / E2 = 1.
  E1 / E2 = f1kw1 / f2kw2.
  E1 / E2 = N1 / N2.
  E1 / E2 = N1kw1 / N2kw2.

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Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

  are provided in a synchronous motor to make it self starting.
  are provided on the stator for improving power factor.
  both (A) and (B).
  consists of short-circuited copper bars embedded in the field pole faces.

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Electrical Machines
In a DC generator, the armature reaction results in

 demagnetization of centers of poles.
  magnetization of inter poles.
 magnetization of leading and demagnetization of trailing pole tip.
  demagnetization of leading & magnetization of trailing pole tip.

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Electrical Machines
If the applied voltage of a certain transformer is increased by 50% and the frequency is reduced by 50%, the maximum flux density will (assuming that the magnetic circuit remains unsaturated)

 remain the same as the original
 changes to 0.5 times the original value
 changes to 1.5 times the original value
 changes to three times the original value

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Electrical Machines
Two DC generators having equal open-circuit emfs but slight different load characteristics are operating in parallel, then

  the machine will share load equally.
None of these
 the machine with more drooping characteristic will supply more load.
  the machine with more drooping characteristic will supply less load.

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