Electrical Machines
What is/are the necessary conditions for parallel operation of alternators?

 Both 1and 2
 Frequency should be same
 Speed of alternators should be same
 Terminal voltage is same

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Electrical Machines
For a given torque, reducing divertor resistance of a DC series motor

  Increase in speed but armature currnet remains the same.
  Increase in speed demanding more armature current.
  Decrease in speed but armature current remains the same.
  Decrease in speed demanding less armature current.

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Electrical Machines
Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements,

 1, 2 and 3 are correct
 1, 2 and 4 are correct
 1 and 4 are correct
 2, 3 and 4 are correct

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