1. The joints of the transformer core lamination are staggered so as to:
a) Avoid continuous gap causing increase in the magnetising current
b) To increase the mechanical strenght of the core
c) Avoid undue humming noise
d) All the above
2. In order to reduce hysteresis loss:
a) Core may be laminated
b) Silicon steel may be used as the core material
c) Core may be constructed with any permanent magnetic material
d) Core may be impregnated with varnish
3. Silicon content in iron laminations is kept within 5% as it:
a) Increases the hysteresis loss
b) Increase the hysteresis loss
c) Makes the material brittle
d) Reduces the curie point
4. Conservator is employed to:
a) Takes care about the expansion and contraction of oil
b) Provides fresh air for increasing cooling effect
c) Stores extra oil in case of emergency
d) Provides fresh air for increasing cooling effectively
5. Multi step core is used in a transformer to:
a) Increase the output
b) Decrease the cost of the core material
c) Decrease the cost of the cooper
d) increase the efficiency
6. In a power transformer:
a) Primary winding is always wound with many windings of thin wire
b) Secondary windings are always wound with lesser number of turns of thin wire
c) Low voltage winding is always wound with lesser number of turns of thicker wire
d) High voltage winding is always wound with larger number of turns of thicker wire
7. Grain oriented laminated sheet steel in transformer reduces:
a) Copper loss
b) Eddy current loss
c) Hysteresis loss
d) Both b and c
8. The hum in a transformer is mainly attributed to:
a) Variations in the load
b) Mechanical vibrations
c) Magentostriction
d) both b and c
9. The thickness of the transformer core laminations is:
a) 3 mm to 5 mm
b) 0.35 mm to 0.5 mm
c) 30 mm to 50 mm
d) 0.035 mm to 0.05 mm
10. The all day efficiency of the distribution transformer is defined as the ratio of:
a) Power output to power input in kw during the whole day
b) Energy output to energy input in kwh during the whole day
c) kva output to kva input during whole day
d) kvah output to kvah input during the whole day
a) Avoid continuous gap causing increase in the magnetising current
b) To increase the mechanical strenght of the core
c) Avoid undue humming noise
d) All the above
2. In order to reduce hysteresis loss:
a) Core may be laminated
b) Silicon steel may be used as the core material
c) Core may be constructed with any permanent magnetic material
d) Core may be impregnated with varnish
3. Silicon content in iron laminations is kept within 5% as it:
a) Increases the hysteresis loss
b) Increase the hysteresis loss
c) Makes the material brittle
d) Reduces the curie point
4. Conservator is employed to:
a) Takes care about the expansion and contraction of oil
b) Provides fresh air for increasing cooling effect
c) Stores extra oil in case of emergency
d) Provides fresh air for increasing cooling effectively
5. Multi step core is used in a transformer to:
a) Increase the output
b) Decrease the cost of the core material
c) Decrease the cost of the cooper
d) increase the efficiency
6. In a power transformer:
a) Primary winding is always wound with many windings of thin wire
b) Secondary windings are always wound with lesser number of turns of thin wire
c) Low voltage winding is always wound with lesser number of turns of thicker wire
d) High voltage winding is always wound with larger number of turns of thicker wire
7. Grain oriented laminated sheet steel in transformer reduces:
a) Copper loss
b) Eddy current loss
c) Hysteresis loss
d) Both b and c
8. The hum in a transformer is mainly attributed to:
a) Variations in the load
b) Mechanical vibrations
c) Magentostriction
d) both b and c
9. The thickness of the transformer core laminations is:
a) 3 mm to 5 mm
b) 0.35 mm to 0.5 mm
c) 30 mm to 50 mm
d) 0.035 mm to 0.05 mm
10. The all day efficiency of the distribution transformer is defined as the ratio of:
a) Power output to power input in kw during the whole day
b) Energy output to energy input in kwh during the whole day
c) kva output to kva input during whole day
d) kvah output to kvah input during the whole day
