Winding Of Direct Current Machine Objective Questions and Answers

41.  Aluminium is not used as winding wire in DC machine armature as it

   A. Is costlier

   B. Is of low resistivity

   C. Is of a lower thermal conductivity

   D. Requires large winding space

42.  In a drum type of DC armature winding the back pitch and front pitch in terms of the coil sides must be

   A. Even and odd respectively

   B. Odd and even respectively

   C. Both even

   D. Both odd

43.  Short-circuiting is caused in the armature winding due to

   A. Failure of insulation between two turns of a coil

   B. Failure of insulation between two commutator bars

   C. Grounding of two or more turns of the same coil

   D. Any of the above

44.  In a lap wound DC generator, having P poles and Z conductors the maximum number of equalizer rings will be

   A. Z/P

   B. 2Z/P

   C.Z/2P

   D. Z/4P

45.  The compensating windings are placed in the slots in the pole faces to neutralize the

   A. Cross magnetizing effect

   B. Demagnetizing effect

   C. Both the Cross magnetizing and Demagnetizing effect

   D. Armature reaction mmf under the pole faces and avoid flash over between positive and negative brushes

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