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

 PZL/4Sa²
 PZL/ 4Sa
 PZL/4Sp²
 PZL/4S

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Electrical Machines
In a loaded DC generator, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will

 deteriorate with fall of terminal voltage.
 deteriorate with rise in terminal voltage.
 improve with fall of terminal voltage.
 improve with rise in terminal voltage.

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Electrical Machines
Which of the following represents the commutator pitch?

 Number of commutator segments between two successive coils.
 The distance between the staring of first coil and its next successive coil
 Number of conductors spanned by one coil at the front end of the armature.
 Number of conductors spanned by one coil at the back end of the armature.

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