In a D.C. machine the current per brush arm should not be more than_____________?

Related Mcqs:

1. In a D.C. machine the number of brush arms is _________ the number of poles?

   A. less than
   B. equal to
   C. greater than
   D. none of the above

2. The resistivity of water should not be less than_____________?

   A. 10 Q m
   B. 100 Q m
   C. 1000 Q m
   D. 2000 Q m

3. is usually used for brush rockers____________?

   A. Mild steel
   B. Copper
   C. Aluminium
   D. Cast-iron

4. The efficiency of a machine should be as ____________ as possible to reduce the operating cost?

   A. high
   B. low
   C. either of the above
   D. none of the above

5. The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?

   A. Conduction
   B. Convection
   C. Radiation
   D. All of the above

6. The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?

   A. air
   B. hydrogen
   C. either A. or B.
   D. none of the above

7. The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?

   A. heating time constant
   B. cooling time constant
   C. either A. or B.
   D. none of the above

8. In a D.C. machine, the value of peripheral speed should not, normally, exceed___________?

   A. 10 m/s
   B. 20 m/s
   C. 30 m/s
   D. 40 m/s

9. The operation of a D.C. machine with large air gap lengths is comparatively_____________?

   A. quiet
   B. noisy
   C. either of the above
   D. none of the above

10. The laminations of the armature of a D.C. machine are usually ___________ thick?

    A. 0.1 to 0.2 mm
    B. 0.2 to 0.3 mm
    C. 0.3 to 0.4 mm
    D. 0.4 to 0.5 mm