This research investigates the problem of estimating additional losses in 6 (10)/0.4 kV voltage rating double-wound power transformers caused by asymmetric active-inductive load with a delta connection. This research used the symmetrical components method, modern methods of analysis and synthesis of electric circuits, the theory of electric circuits, full-scale experiment, and comparative experiment. The research found a functional dependence that enables estimating additional losses in the transformer caused by asymmetric load, which differs from similar ones in that it uses phase resistance. The amperage, voltage, and active power was measured in each phase of the “distribution transformer – asymmetric load” model to confirm the discovered functional dependence. The experiments showed that the loss of active power, calculated according to the standard formula, should be corrected with regard to the discovered functional dependence. The practical value of the offered functional dependence for the estimation of additional losses is that it enables estimating the losses of active power in transformers due to asymmetry by measured voltage, amperage, and active power for each phase. This makes it universal: there is no need to build equivalent circuits and carry out calculations according to the symmetrical components method.
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.