Voltage harmonic effect on losses in distribution transformers

The effects of harmonic contamination on distribution transformer losses and temperature rise have become an increasing concern. This problem is caused by the widespread presence of non-linear loads and their ever-increasing proportion in the power system networks. The paper focuses on the particular effect of voltage harmonics on oil-filled distribution transformers losses. Laboratory experiments including short circuit and open circuit tests were conducted on two distribution transformers of different age. The results reveal significant increase in losses. Equations are proposed for correcting the calculation of the total transformer loss.