High energi consumption distribution transformers mainly refer to SJ, SJL, SL7, S7 and other series transformers. Their iron loss and copper loss are much higher than those of S9 series transformers widely used at present. For example, compared with S9, the iron loss of S7 is 11% higher and the copper loss is 28% higher. However, new transformers, such as S10 and S11, are more energy-saving than S9, and the iron loss of amorphous alloy transformer is only 20% of S7. Generally, the service life of transformer is as long as several decades. Replacing high energy consumption transformer with high efficiency energy-saving transformer can not only improve the energy conversion efficiency, but also achieve considerable power saving effect during the service life.