Electrical Machines
A 4 pole wave wound dc motor having flux per pole of 9.56 X 10-3 Wb contains 460 armature conductors. Calculate the back emf produced when it is running at a speed of 1500 rpm.

 240 volt.
 230 volt.
  220 volt.
 440 volt.

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

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

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Electrical Machines
For a single phase capacitor start induction motor which of the following is valid?

 Rotation can be changed by interchanging supply terminals.
  Rotation can be changed by reversing main winding terminals.
 None of these.
 Direction of rotation cannot be changed.

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