Important Electrical Machine Design Multiple Choice Questions and Answers

31.  In a DC machine with the increase in number of poles all of the following increases except

   A. Iron losses

   B. Labour charges

   C. Overall size of the machine

   D. Tendency of flash over

32.  In a larger size DC machine the contactors are of...........in cross-section

   A. Circular

   B. Rectangular

   C. Triangular

   D. None of the above

33.  In a DC machine the diameter of an armature is governed buy

   A. Pole pitch

   B. Peripheral speed

   C. Core length

   D. Both A or B

34.  In a DC machines the width of ventilating ducts usually varies from

   A. 4 to 5 mm

   B. 8 to 10 mm

   C. 12 to 15 mm

   D. 2 to 3 mm

35.  In DC machines air gap is ............in comparison to that in ac machines

   A. Very short

   B. Short

   C. Longer

   D. Any of these

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