A fully insulated UHV transformer made by Yawei in Hai'an, Nantong. [Photo/WeChat account: hafbwx]

China's first fully insulated ultra-high-voltage, large-capacity transformer (250MVA/345kV) was completed on Nov 25 at Yawei Transformer in Hai'an, and has now been packed and shipped to the United States.

The milestone was achieved following an international bidding process earlier this year, where Yawei secured an order from a US power company for three specialized transformers. These products had to meet strict requirements — high capacity, ultra-high voltage, and full insulation — a market segment that no Chinese manufacturer had previously entered.

After securing the contract in late April, Yawei established a dedicated R&D team to address the technical challenges. Engineers conducted thorough studies on electromagnetic design and structural layout to identify the best solution. The team then utilized Siemens' latest simulation and verification software to model the entire physical process and confirm the design's validity.

In under three months, Yawei independently designed, manufactured, and self-tested the transformer. The product has passed all factory tests and is now heading to the United States, representing a significant breakthrough for China in high-specification transformer engineering.