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.Management Sciences
Category: Electrical Machine Design
The stator of a D.C. machine comprises of_____________?
A. main poles
B. interpoles
C. frame
D. all of the above
In a D.C. machine the number of brush arms is _________ the number of poles?
A. less than
B. equal to
C. greater than
D. none of the above
The cylindrical windings using circular conductors are used for current rating of____________?
A. upto 20 A
B. upto 40 A
C. upto 60 A
D. upto 80 A
Which of the following is the commonly used type of electromagnets ?
A. Flat-faced armature type
B. Horse shoe type
C. Flat-faced plunger type
D. All 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 action of electromagnetic machines can be related to which of the following basic principles __________?
A. Induction
B. Interaction
C. Alignment
D. All of the above
Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?
A. Equivalent power method
B. Equivalent current method
C. Method of average losses
D. Equivalent torque method
A current density of __________ is ilsed for large power transformers with forced circulation of oil or with water cooling coils?
A. 1.5 to 2.5 A/mm2
B. 3.5 to 4.5 A/mm2
C. 4.0 to 5.0 A/mm2
D. 5.4 to 6.2 A/mm2
On which of the following variables heat convected depends ?
A. Power density
B. Temperature difference between heated surface and coolant
C. Thermal resistivity, density, specific heat
D. Gravitational constant
E. All of the above
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