A. Copper
B. Aluminium
C. Steel
D. Cast-iron
0
On which of the following variables heat convected depends ?
0
The mcrease in heat dissipation by air blasts is due to increase in______________?
A. Power density
B. Temperature difference between heated surface and coolant
C. Thermal resistivity, density, specific heat
D. Gravitational constant
E. All of the above
0
Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?
A. conduction
B. convection
E. radiation
D. any ofthe above
0
Hydrogen has a heat transfer co-efficient __________ times that of air?
A. 10 MW
B. 30 MW
C. 60 MW
D. 150 MW
0
With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?
A. 1.5
B. 2.5
C. 3.5
D. 4.5
0
cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?
A. 50 MW
B. 100 MW
C. 200 MW
D. none of the above
0
The thermal conductivity of hydrogen is _____________ times that of air?
A. Direct
B. Indirect
C. Conventional
D. Any of the above
0
The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?
A. 2
B. 3
C. 5
D. 7
0
The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
A. air
B. hydrogen
C. either A. or B.
D. none of the above
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