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

Related Mcqs:

1. 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

2. 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

3. 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

4. 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

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

   A. 100 A
   B. 200 A
   E. 300 A
   D. 400 A

6. 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

7. 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

8. The stator of a D.C. machine comprises of_____________?

   A. main poles
   B. interpoles
   C. frame
   D. all of the above

9. 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

10. In _________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?

    A. small
    B. medium
    C. large
    D. any of the above.