DGVCL Exam Paper (11-12-2011)
DC series motors are best suited for traction work because

Its torque is proportional to the square of the armature current and speed is inversely proportional to torque
Torque and speed are proportional to the square of the armature current
Torque and speed are inversely proportional to the square of the armature current
Its torque is proportional to the square of the armature current and speed is directional proporational to torque

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DGVCL Exam Paper (11-12-2011)
The purpose of embedding the damper winding in the pole face of a synchronous motor is to

Eliminate losses on account of fair friction
Reduce winding losses
Eliminate hunting and provide adequate starting torque
Reduce bearing friction

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DGVCL Exam Paper (11-12-2011)
The advantage of slipring induction motor over the squirrel cage induction motor is

It can be started with the help of rotor resistances
It's power factor is higher
It is suitable for higher speeds
It has a higher efficiency

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