A. 2
B. 3
C. 5
D. 7
Related Mcqs:
- Hydrogen has a heat transfer co-efficient __________ times that of air?
A. 1.5
B. 2.5
C. 3.5
D. 4.5 - The density of hydrogen is __________ times the density of air?
A. 0.07
B. 1.5
C. 2.5
D. 3.5 - 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 mcrease in heat dissipation by air blasts is due to increase in______________?
A. conduction
B. convection
E. radiation
D. any ofthe above - The operation of a D.C. machine with large air gap lengths is comparatively_____________?
A. quiet
B. noisy
C. either of the above
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 - The forced oil and air circulation method is usual one for transformers of capacities____________?
A. upto 5 MVA
B. upto 10 MVA
C. upto 20 MVA
D. 30 MVA upwards
