Core losses profit in rural monophase transformers by means of percent impedance optimization

This paper presents a study aiming the project of efficient monophase distribution transformers to be used in regions of low energy demand. In these regions, due to the clients profile, no load losses are more expressive than losses in copper. The study necessary for the realization of this work was based on a survey accomplished by AES Sul - Distribuidora Gaúcha de Energia in partnership with the High Voltage Laboratory of Federal University of Itajubá - LAT-EFEI. Through this study, it was found that most of the transformers in rural area operate with low demand, not exceeding, in some cases, the limit of 0, 3 p.u. In these conditions, it is necessary to prioritize the reduction of no load losses so that the transformer can operate efficiently. This work introduces an analysis based on optimization of the percent impedance of the monophase distribution transformer aiming the reduction of losses in the core, indicating that on contrary to common sense, the increase of the percent impedance can result in a transformer with low costs and low no load losses, presenting reduced total losses if used under indicated loading conditions.