Electrical Machines
A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping

 Rf maximum and Ra minimum
 Ra maximum and Rf minimum
 Ra maximum and Rf maximum
 Ra minimum and Rf minimum

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

  Decrease in speed demanding less armature current.
  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.

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Electrical Machines
An inverted V curve of synchronous motor shows variation of

 supply voltage and field current at constant excitation.
 power factor and supply voltage during hunting.
 supply voltage and excitation current at constant load.
  power factor and DC excitation at constant load.

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