Evaluation of performance of distribution transformers supplying non linear loads currents: Effect of oversizing

Harmonic currents, generated by non-linear loads, produce `penalty losses' in every element of an electrical distribution system. These harmonic-related losses reduce system efficiency, cause apparatus overheating, and increase power and air conditioning costs. In this paper, evaluation of transformer losses under non-linear load conditions will be discussed. In addition, the results of practical measurements of full filled on 7 units of distribution transformers in Tabriz Power Electric Distribution network are evaluated and some suggestions to improve the situation are presented.