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

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

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

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

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Electrical Machines
What will happen if the the supply terminals are reversed in case of a DC shunt motor?

 The motor will stop.
 The motor will run much faster in the same direction.
 The motor will run in reverse direction.
 The motor will run at its normal speed in the same direction as before.

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