Efficient operation regions of power distribution transformers

A new concept of efficient operation regions of distribution transformers on power factor versus active power (cos ) plane is proposed. Based on it a visual analysis method is obtained to determine efficient ranges of operating transformers. This method could be used for analyzing efficiency of transformer loading based on databases of the distribution automation system, and the real-time operational loci of distribution transformers could also be obtained. An application of this method in a 10 kV overhead distribution automation system is given.