In direct cooled system using hydrogen both stator and rotor conductors are made____________?
A. solid
B. hollow
C. perforated
D. any ofthe above
Electrical Machine Design
The resistivity of water should not be less than_____________?
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
Machines cooled by direct cooling method may be called_____________?
Machines cooled by direct cooling method may be called_____________?
A. “supercharged”
B. “inner cooled”
C. “conductor cooled”
D. any of the above
The density of hydrogen is __________ times the density of air?
The density of hydrogen is __________ times the density of air?
A. 0.07
B. 1.5
C. 2.5
D. 3.5
Which of the following is an advantage of hydrogen cooling ?
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
The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
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
The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?
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
The thermal conductivity of hydrogen is _____________ times that of air?
The thermal conductivity of hydrogen is _____________ times that of air?
A. 2
B. 3
C. 5
D. 7
cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?
cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?
A. Direct
B. Indirect
C. Conventional
D. Any of the above
With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?
With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?
A. 50 MW
B. 100 MW
C. 200 MW
D. none of the above