High-energy distribution transformers mainly refer to: SJ, SJL, SL7, S7 and other series transformers, whose iron loss and copper loss are much higher than those of the widely used S9 series transformers. For example, compared with S9, S7 has higher iron loss 11%, copper loss is 28% higher.

The new transformers, such as S10 and S11 transformers are more energy-efficient than S9, and the iron loss of amorphous alloy transformers is only equivalent to 20% of S7. Transformers generally have a service life of several decades. Replacing high-energy-consumption transformers with high-efficiency energy-saving transformers can not only improve energy conversion efficiency, but also have considerable power-saving effects during the lifespan.