Derating of a distribution transformer for non-linear loads

This paper deals with an important problem related to power quality that has been tackled in the literature quite often. The three-phase distribution transformer in electrical power systems is generally installed for supplying loads with rated frequency. Non-linear loads introduce harmonics to the supply and result in a different performance compared with that of the designed transformer. In this paper a three-phase 50kVA distribution transformer is modeled using the finite element (FE) method in order to evaluate its losses under non-linear loads. Comparison of the FE computation results with the analytical standard method results shows that the latter method leads to a more conservative estimate of the transformer derating. Copyright (c) 2005 John Wiley & Sons, Ltd.