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.Management Sciences
Category: Electrical Machine Design
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
____________ is the common method of applying brushes to the commntator?
A. Radial
B. Trailing
C. Reaction
D. All of the above
Electrical machines having power outputs ranging from a few kW up to approximately 250 kW may be classified as_____________?
A. small size machines
B. medium size machines
C. large size machines
D. any of the above
The distance between the starts of two consecutive coils measured in terms of coil sides is called_____________?
A. front pitch
B. winding pitch
C. commutator pitch
D. back pitch
Disc windings are primarily used in_____________-?
A. short capacity transformers
B. medium capacity transformers
C. high capacity transformers
D. any of the above
Power transformers should be designed to have maximum efficiency________________?
A. at one-fourth load
B. at one-half load
C. at or near full load
D. any of the above
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