Electrical Machines
For a DC machine having P no of pole pairs Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance for lap-winding ?

 PZL/4S
 PZL/4SP²
 PZL/ 4Sa
 PZL/4Sa²

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Electrical Machines
Compensating windings are used in DC generators

  mainly to reduce the eddy currents by providing local short circuit.
  to provide path for the circulation of cooling air.
None of these
  to neutralize the cross magnetizing effect of the armature reaction.

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Electrical Machines
Consider the following statements: To control the speed of a dc shunt motor above the base speed over a reasonably wide range, the motor must 1. have compensating winding 2. have interpole winding 3. be started using a 3-point starter 4. be started using a 4-point starter Of these statements

 2 and 4 are correct
 1 and 3 are correct
 1, 2 and 4 are correct
 1, 2 and 3 are correct

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