A. 1.5
B. 2.5
C. 3.5
D. 4.5
Related Mcqs:
- The density of hydrogen is __________ times the density of air?
A. 0.07
B. 1.5
C. 2.5
D. 3.5 - The thermal conductivity of hydrogen is _____________ times that of air?
A. 2
B. 3
C. 5
D. 7 - 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 mcrease in heat dissipation by air blasts is due to increase in______________?
A. conduction
B. convection
E. radiation
D. any ofthe above - 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 - 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 - In direct cooled system using hydrogen both stator and rotor conductors are made____________?
A. solid
B. hollow
C. perforated
D. any ofthe above - The length cf air gap to be provided in __________ is primarily determined by power factor consideration?
A. d.c. series motor .
B. d.c. shunt motor
C. induction motor
D. synchronous motor - 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 - The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?
A. Corrugations
B. Fins
C. Tubes
D. Radiator tanks
E. All of the above
