Abstract
Fluorinated nitrile (C4F7N) is a potential SF6-alternative gas in Gas-Insulated Transmission Line (GIL) due to its lower impact to global warming and excellent dielectric strength. To ensure the long-term physical and chemical stability at the interface between C4F7N/CO2 gas and epoxy resin assembly in GIL, laboratory thermal ageing tests on the material compatibility were carried out. In order to evaluate the compatibility, the authors set up a gas-solid compatibility test platform in this paper. Thermal ageing tests of C4F7N/CO2 and epoxy resin were set up at different temperatures. Also, the groups of SF6 and He gas were adopted to evaluate the influence of temperature. The compatibility between the gas and solid insulating materials in contact was evaluated in terms of the changes of insulation performance after over long period of tests. The changes of gas compositions and solid contents were also assessed. Dielectric spectroscopy, surface flashover voltages, surface morphology, and chemical elements of epoxy resin and gas composition before and after the ageing tests were compared. The surface insulation of epoxy resin decreased only after ageing reached 160 °C, when a small amount of C3F6 and trimer of C4F7N were found. Under the normal operation of GIL (below 90 °C), the compatibility of epoxy resin with 9 % C4F7N/91 % CO2 is as good as epoxy resin with SF6.
Highlights
In 2015, the 3M Company introduced the environmentally friendly insulating gas fluorinated nitrile (C4F7N) which has stable chemical properties, great dielectric (1.9 times that of SF6), environmental properties (Global Warming Potential value of 2100) and about 30 years of atmospheric life
Since C4F7N has a high liquefaction temperature (−4.7 ◦C) [2], it is necessary to mix with buffer gases with lower liquefaction temperature such as CO2, N2 or air to meet the operational requirements of the equipment in winter
The results showed that C4F7N had good compatibility with copper and aluminum, and the compatibility of C4F7N with aluminum was better than that copper, which explained the reason why C4F7N had good compatibility with metal theoretically
Summary
In 2015, the 3M Company introduced the environmentally friendly insulating gas fluorinated nitrile (C4F7N) which has stable chemical properties, great dielectric (1.9 times that of SF6), environmental properties (Global Warming Potential value of 2100) and about 30 years of atmospheric life. It has superior environmental performance over SF6 [1]. The results showed that 9 % C4F7N/91 % CO2, under uniform electric field and equal pressure, reached the same insulation strength as pure SF6 [4] As a result, it has become one of the potential alternative gases for SF6
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
