41. The transformer efficiency will be maximum at a power factor of
- 0.8 lead
- 0.8 lag
- unity
- none of the above
42. The all day efficiency of a distribution transformer will be high with low
- copper losses
- iron losses
- operating temperature
- copper as well as iron losses
43. The desirable properties of a transformer core material are
- low permeability and low hysteresis loss
- high permeability and high hysteresis loss
- high permeability and low hysteresis loss
- low permeability and high hysteresis loss
44. The use of higher flux density in the transformer design
- reduces the weight per kVA
- increases the weight per kVA
- has no relation with the weight of transformer
- increases the weight per kW
45. What does the use of higher flux density value in a transformer design lead to
- increase in weight per kVA
- decrease in weight per kVA
- reduced iron losses
- reduced copper losses
46. The size of the transformer core depends upon
- area of the core
- frequency
- permissible flux density in the core material
- frequency and permissible flux density in the core material
47. Ferrite cores are employed in high frequency transformers due to
- low resistance
- high resistance
- low permeability
- high hysteresis loss
48. Cores of large power transformers are made from which one of the following?
- hot rolled steel
- cold rolled non-grain oriented steel
- cold rolled grain oriented steel
- ferrite
49. Grain oriented laminated sheet steel in transformer reduces
- copper loss
- eddy current loss
- hysteresis loss
- none of the above
50. If the iron core of a transformer is replaced by an air core, then the hysteresis losses in the transformer will
- increase
- decrease
- remain unchanged
- become zero