Electrical Machines
To increase starting torque of a 3-phase slip ring induction motor, preferred method is to increase

None of these
 supply voltage
 rotor resistance
 supply frequency

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

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