Who are the major transformer oil producers in China?

The major transformer oil producers in China include Sinopec, PetroChina, and CNOOC. These companies dominate the market, producing high-quality mineral and synthetic transformer oils essential for electrical insulation and cooling in power transformers. Additionally, smaller companies like Shandong Wanshan and Zhejiang Huaneng also contribute to the industry, but the primary market share is held by the aforementioned giants.