Electrical Machines
For satisfactory parallel operation of two transformers which of the following conditions is most essential,

 percentage impedance of all transformers must be same.
 MVA rating of all transformer inversely proportional to impedance.
  polarities of all transformers must be same.
 voltage ratio of all transformers must be same.

ANSWER DOWNLOAD EXAMIANS APP

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 three times the original value
 changes to 1.5 times the original value

ANSWER DOWNLOAD EXAMIANS APP

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

 increase in speed demanding more armature current.
 increase in speed but armature currnet remains the same.
 decrease in speed but armature current remains the same.
 decrease in speed demanding less armature current.

ANSWER DOWNLOAD EXAMIANS APP