A. solid
B. hollow
C. perforated
D. any ofthe above
Related Mcqs:
- 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 - In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?
A. equal to that of armature mmf
B. less in comparison with the armature mmf
C. large in comparison with the armature mmf
D. none of the above - Machines cooled by direct cooling method may be called_____________?
A. “supercharged”
B. “inner cooled”
C. “conductor cooled”
D. any of the above - Direct water cooling of rotor winding presents_____________?
A. no mechanical difficulties
B. lesser mechanical difficulties
C. greater mechanical difficulties
D. none of the above - The stator of a D.C. machine comprises of_____________?
A. main poles
B. interpoles
C. frame
D. all of the above - The cylindrical windings using circular conductors are used for current rating of____________?
A. upto 20 A
B. upto 40 A
C. upto 60 A
D. upto 80 A - Cylindrical windings using circular conductors, employed in transformers, are_____________?
A. single layered
B. double layered
C. multi-layered
D. none of the above - In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
A. 2 to 3 times greater
B. 3 to 4 times greater
C. 4 to 5 times greater
D. none of the above - For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?
A. 1.0 to 1.2 A/mm2
B. 1.5 to 2.0 A/mm2
C. 2.2 to 3.2 A/mm2
D. 3.2 to 4.2 A/mm2 - Hydrogen has a heat transfer co-efficient __________ times that of air?
A. 1.5
B. 2.5
C. 3.5
D. 4.5
