As early as in the 70s Shanghai and Beijing transformer factory successively developed thick insulation with quartz powder filler in the vacuum state casting epoxy resin encapsulated dry-type transformers, from then on dry-type transformers in China officially become a batch supply of a new generation of products, although at that time it was replaced by the thin insulation technology of pure epoxy resin due to some problems in the material, manufacturing process, but after all it created a good start for dry-type transformers, promoting the development of dry-type transformer technology in China.

As the thick insulation is difficult to solve the cracking problem, when people are doubtful about the epoxy resin dry-type transformer technology, Shunde Transformer Factory successfully introduced the pure epoxy resin thin insulation (1-3mm) technology without quartz filler from Germany, which appeared and made the technology of dry-type transformer in China develop rapidly.

As the quality of products of this technology was more stable (with imported casting equipment and imported resin), users were more satisfied. Coupled with the better economic benefits of manufacturing plants at that time, we have been on the horse. At first more than 10, then 30, 70, now there are more than 100 adopt this technology. Currently has accounted for 90-95% of the dry transformer market, production capacity has been more than 30 million kVA per year. supply has been much greater than demand. This kind of transformer we are already familiar with, we will not say more.

At the beginning of this century, Shanghai GE company adopted American technology to research and develop H-class insulation with filler thin insulation epoxy resin vacuum casting dry-type transformer, the transformer's internal part of the insulation material using NOMEX insulation paper. It has successfully solved the technical problems of insulation fit between various insulation components inside the transformer, process formula and casting uniformity. Its appearance has improved the insulation heat resistance level of epoxy resin encapsulated dry-type transformers from B and F to H. However, it is impossible to improve it to C level with the current technology.