The first 500kv GIL using C4 gas is operating with electricity in China

The first environmentally friendly gas insulated equipment with the highest voltage level in the country has successfully operated with electricity
Recently, the first 550 kV perfluoroisobutyronitrile (C4F7N, abbreviated as C4) environmentally friendly gas insulated metal enclosed transmission pipeline (abbreviated as GIL) in China was put into live operation at the 500 kV Rongsheng substation in Anqing. This is the highest voltage level environmentally friendly gas insulated electrical equipment for engineering applications in China.
Sulfur hexafluoride (SF6) gas is widely used in electrical equipment due to its excellent insulation and arc extinguishing properties, but it has a high potential for greenhouse effect and has been strictly controlled and constrained.
State Grid Corporation of China issued Document No. 290 in 2022, promoting SF6/N2 mixed gas as a substitute for SF6 pure gas in GIS and GIL. Currently, SF6/N2 mixed gas is basically used for all newly built 110-220kV GIS in State Grid of China.

C4 is a new type of environmentally friendly insulating gas, with a greenhouse effect about one tenth that of sulfur hexafluoride and an insulation strength about 2.2 times that of sulfur hexafluoride. It has become internationally recognized as the most promising SF6 alternative gas and is one of the solutions to replace SF6.

To solve this problem, since 2017, Anhui Electric Power Co., Ltd., a subsidiary of State Grid Corporation of China, has collaborated with advantageous units such as China Electric Power Research Institute Co., Ltd. to carry out joint research and development. In 2019, the localization of C4 gas industrial preparation was successfully achieved, and the insulation design basis and compatibility evaluation indicators for C4 gas electrical equipment were proposed. In May 2021, the 12 kV C4 environmentally friendly gas ring main unit developed by the team was put into operation on the grid in Anhui and achieved large-scale application. The first batch of equipment has been running stably for over 4 years with excellent performance, further verifying the reliability of long-term operation of C4 environmentally friendly gas.