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.Management Sciences
Category: Electrical Machine Design
Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors ?
A. Copper
B. Aluminium
C. Steel
D. Cast-iron
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
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
Which of the following methods may be adopted to reduce the effects of armature reaction ?
A. Increase in length of air gap at pole tips
B. Increasing reluctance of pole tips
C. Compensating windings
D. Interpoles
E. All of the above
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
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