Recently, Shanghai Huaming Electric Power Equipment Manufacturing Co., Ltd. independently developed to sulfur hexafluoride as the insulating medium on-load tap- changer tap-changer acceptance by experts, marking China's 220kV to SF6 dielectric transformer production towards a new area . The product design is safe and reliable, can play a role in extreme conditions such as low temperature, humidity, widely used in industrial and mining, underground and other places. At present, China's power grid operation of 110kV and below power transformer "gas" tap-changer field monopolized by foreign companies in the development and use of 220kV on-load tap-changer is still blank, research and development with independent intellectual property rights, "Gas "On-load tap-changers are imminent. As early as 2009, Wah Ming successfully delivered the first on-load tap-changer of 110kVSF6 insulated transformer and it is currently operating well. In order to further break the monopoly in this field, Wah Ming's technical team continually tackled the challenge and finally completed the delivery of the on-load tap-changer for the first 220kV SF6 gas-insulated transformer in July 2014 in China. As the first domestic manufacturer to successfully develop tap changers for "gasification", 220kVSF6 on-load tap-changers have filled the gap in China. Already has a number of patented technologies, but Wah Ming will continue to explore, with excellent quality, cost-effective products for China's power grid construction to make new contributions. (Yang Hongying)