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.Management Sciences
Category: Electrical Machine Design
In direct cooled system using hydrogen both stator and rotor conductors are made____________?
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A. solid
B. hollow
C. perforated
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
The winding where dummy coils are used is sometimes called______________?
A. duplex winding
B. triplex winding
C. forced winding
D. none of the above
If an insulating material is operated beyond the maximum allowable temperature, its life is_____________?
A. drastically increased
B. drastically reduced
C. unaffected
D. none of the above
Cylindrical windings using circular conductors, employed in transformers, are_____________?
A. single layered
B. double layered
C. multi-layered
D. none of the above
The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?
A. 0.5 to 0.8 Wb/m2
B. 0.8 to 1.0 Wb/m2
C. 1.1 to 1.35 Wb/m2
D. 1.4 to 1.8 Wb/m2
The mcrease in heat dissipation by air blasts is due to increase in______________?
A. conduction
B. convection
E. radiation
D. any ofthe above
In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?
A. 5 percent
B. 10 percent
C. 15 percent
D. 30 percent
E. none of the 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
___________ brushes are fragile and cause excessive wear of commutator?
A. Natural graphite
B. Hard carbon
C. Electro graphitic
D. Metal graphite
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