Selection of distribution transformer based on economic criteria

This paper presents considerations related to the loss of life calculation and to the determination of the distribution transformers loading, with technical and economical considerations and applying daily load curves obtained from measurements in typical transformers. Loss of life estimation is done applying probabilistic daily load curves and their probability of occurrence. The transformer loading management criteria is then compared to the methodology presently in use by Sao Paulo State electric utilities (Brazil). Finally a transformer loading analysis is performed using economic criteria that consists of the calculation of the investment cost, losses and the loss of life cost, all during the operational life of the transformer.