Top 150+ Solved Design of Electrical Machines MCQ Questions Answer
Q. The cold rolled grain oriented steel has ______ permeability in the direction of thegrain orientation.
a. minimum
b. maximum
c. nil
d. none of the above
Q. Cylindrical windings using circular conductors, employed in transformers, are
a. single layered
b. double layered
c. multi-layered
d. none of the above
Q. Helical windings are used in
a. distribution transformers
b. power transformers
c. shell type transformers
d. none of the above
Q. Multi-layer helical windings are commonly used in the transformers as high voltagewindings
a. upto 20 kV
b. upto 50 kV
c. upto 80 kV
d. for 110 kV and above
Q. Disc windings are primarily used in
a. short capacity transformers
b. medium capacity transformers
c. high capacity transformers
d. any of the above
Q. The heat dissipating capability of transformers of ratings higher than 30 kVA inincreased by providing which of the following ?
a. Corrugations
b. Fins
c. Tubes
d. All of the above
Q. Transformers with a capacity of upto _____ have a cooling radiator system with naturalcooling
a. 2 MVA
b. 5 MVA
c. 7.5 MVA
d. 10 MVA
Q. 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
Q. 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
Q. D.C. windings are
a. sometimes 2-layer type
b. never 2-layer type
c. always 2-layer type
d. none of the above
Q. The usual values of maximum flux densities for distribution transformers using hotrolled 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
Q. For 275 kV transformers, using cold rolled grain oriented steel, which of the followingvalues of flux density may be used?
a. 1.0 Wb/m2
b. 1.1 Wb/m2
c. 1.3 Wb/m2
d. 1.6 Wb/m2
Q. For large power transformers, self oil cooled type or air blast type which of thefollowing 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
Q. A current density of _____ is ilsed for large power transformers with forced circulationof 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