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.Management Sciences
Category: Electrical Machine Design
In D.C. machines the number of slots per pole usually lies___________?
0
A. between 2 to 4
B. between 6 to 8
C. between 9 to 16
D. between 20 to 30
D.C. windings are____________?
A. sometimes 2-layer type
B. never 2-layer type
C. always 2-layer type
D. none of the above
Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?
A. 10 MW
B. 30 MW
C. 60 MW
D. 150 MW
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
When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of_____________?
A. short pitch
B. full pitch
C. either of the above
D. none of the above
Which of the following is an advantage of hydrogen cooling ?
A. Increase in efficiency
B. Increase in ratings
C. Increase in life
D. Smaller size of coolers
E. All of the above
____________are used for construction of core of electromagnets?
A. Soft magnetic materials
B. Hard magnetic materials
C. Either A. or B.
D. None of the above
__________ has a low relative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable?
A. Cast steel
B. Aluminium
C. Soft steel
D. Cast iron
electromagnets generally function as holding magnets ?
A. Tractive
B. Portative
C. Either of the above
D. None of the above
The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc?
A. conduction
B. convection
C. radiation
D. any of the above
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