Additional Loss in the Core of Three Phase Transformers Feeding Non Linear Loads

As a consequence of the increasing technological development of electrical and electronic equipments, which are supplied by distribution transformers, the current and the voltage of transformers have presented distorted waveforms. These non-sinusoidal currents and voltages in transformers result in additional losses, which cause increase in temperature and reduction to the transformer insulation and lifetime. One of these losses is located in the transformer core, which may cause increase in the excitation current and in the audible noise. The purpose of this work is to analyse the behaviour of the voltages and currents of distribution transformers when they are supplying energy to non-linear loads and, from this analysis, to calculate the Core Loss (PNL). The measurements are performed using the back-to-back configuration and the adopted model is the three-phase instantaneous model with measurements and calculus made per phase. This work is implemented using a Data Acquisition System (DAQ) and the LabVIEW programming language.