Important Electrical Machine Design Multiple Choice Questions and Answers

6.  The higher commuter peripheral speeds generally leads to

   A. Commutation difficulties

   B. Ventilation difficulties

   C. Both A and B

   D. None of the above

7.  Mica is used to insulate the commutator segments because

   A. It has a very high specific weight

   B. It is mechanically strong

   C. It is cheaper

   D.Both A and B

8.  In a DC machine if the number of slots in the armature are more

   A. Cooling is likely to be poor

   B. Commutation will be poor

   C. Cost will be more

   D. The flux pulsation will be more

9.  The brushes of a DC motor suitable for rotation in any direction should be placed as

   A. Radial

   B. Reaction

   C. Trailing

   D. Any of the above

10.  Reactance voltage in a DC machine

   A. Increases in direct proportion with the increase in number of commutator segments

   B. Increases linearly with the increase in speed of the machine

   C. Increases with the increase in brush thickness

   D. All of the above

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