44) Results of a transformer with a rating of 15 kVA, 1100V/ 220V, 50Hz are obtained, while testing. Short circuit test power input = 510 watts. Open circuit test power input = 252 watts. What is the efficiency of the transformer at full load, 0.8 p.f.?

45) What is the maximum load upto which an open delta transformer can safely maintain supply to load ?

46) What is the cause for producing humming noise in the transformer core ?

47) No load loss of a transformer has two components. They are eddy current and hysteresis loss. In which part of a transformer hysteresis loss will occur ?

48) Which material is used for the construction of the power transformer core ?