Electrical Machines
In a DC generator in case the brushes are moved so as to bring them in magnetic neutral axis, then, there will be

  cross-magnetization as well as demagnetization.
  none of above.
 demagnetisation.
  cross-magnetisation.

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Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

 a counter-emf is induced in the coil undergoing commutation
 the inequality of air-gap flux on the top and bottom halves of the armature is removed
 the interpoles produce additional flux to augment the developed torque
 the flux waveform is improved with reduction in harmonics

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Electrical Machines
In case of 3 - Φ IM, plugging means

  locking of rotor due to harmonics.
  pulling the motor directly on line without a rotor.
  starting the motor on load which is more than the rated load.
  interchanging two supply phases for quick stopping.

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Electrical Machines
A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will

 increase to 1.25 times 220 V
 increase to value lying between 220 V and 1.25 times 220 V
 not change and remain at 220 V
 increase to a value greater than 1.25 times 220 V

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