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.Management Sciences
Category: Electrical Machine Design
The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?
A. minimum
B. maximum
C. nil
D. none of the above
Power transformers have rating_______________?
A. equal to 50 kVA
B. equal to 100 kVA
C. above 200 kVA
D. none of the above
The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?
A. heating time constant
B. cooling time constant
C. either A. or B.
D. none of the above
The insulation between windings and grounded core and the insulation between the windings of the same phase is called__________________?
A. minor insulation
B. major insulation
C. either of the above
D. none of the above
The voltage control in electric supply networks in required on account of which of the following reasons ?
A. Adjustment of voltage at consumers premises within statutory limits
B. Control of active and reactive power
C. Adjustment of short period daily and seasonal voltage variations in accordance with variations of load
D. All of the above
In a D.C. machine the current per brush arm should not be more than_____________?
A. 100 A
B. 200 A
E. 300 A
D. 400 A
In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
A. 2 to 3 times greater
B. 3 to 4 times greater
C. 4 to 5 times greater
D. none of the above
The laminations of the armature of a D.C. machine are usually ___________ thick?
A. 0.1 to 0.2 mm
B. 0.2 to 0.3 mm
C. 0.3 to 0.4 mm
D. 0.4 to 0.5 mm
In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?
A. increase
B. decrease
C. either of the above
D. none of the above
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