As early as the 1970s, Shanghai and Beijing transformer plants successively developed epoxy-encapsulated dry-type transformers that were cast in a vacuum state with a thick insulating tape filled with quartz powder. Since then, dry-type transformers have officially become a new generation of bulk-supply products, although At the time, it had problems in materials and manufacturing processes and was replaced by the thin insulation technology of pure epoxy resin. However, it created a good start for dry-type transformers and promoted the development of dry-type transformer technology in China.

Because thick insulation is difficult to solve the cracking problem and people are doubting about epoxy resin dry-type transformer technology, Shunde Transformer Factory successfully introduced pure epoxy thin insulation (1-3mm) technology without quartz filler from Germany. The emergence of China's dry-type transformer technology has rapidly developed.

Because of the relatively stable product quality of this technology (with imported pouring equipment and imported resin), users are satisfied. With the better economic benefits of the manufacturing plant at that time, everyone started to launch. More than 10 began, followed by 30, 70, and now more than 100 use this technology. At present, it has accounted for 90-95% of the dry-change market, and its annual production capacity has exceeded 30 million kVA. The supply has been greater than for much better. Everyone is already familiar with this type of transformer, and we won't say much about it.

At the beginning of this century, Shanghai GE adopted U.S. technology to research and develop Class H insulated, thin-insulated epoxy resin vacuum-pumped dry-type transformers with a filler. Some of the transformer's internal insulation uses NOMEX® insulation paper. He succeeded in solving the technical problems of insulation coordination, process recipes, and casting uniformity between various insulating components inside the transformer. Its appearance has raised the heat-insulating rating of epoxy-encapsulated dry-type transformers from Class B and Class F to Class H, but the current technology is impossible to raise to Class C.