Investigation of Environmentally Sound Insulating Gases for High Voltage Applications

The issue of climate change has gained increasing attention in recent years. The emissions of greenhouse gases (GHG) are steadily increasing, having reached unprecedented values due to intensified human activities. The power industry makes use of sulphur hexafluoride (SF6) for its favourable properties as an insulating and arc-quenching medium. SF6 is a GHG with a global warming potential (GWP) that is 24,300 times higher than carbon dioxide (CO2). SF6 has a very long atmospheric lifetime of over 3,200 years and no viable replacements have been found for all its applications. As a result, SF6 emissions have been increasing at a significant rate in the 21st century. The objectives of this work are:

- Investigate the interaction between gaseous and solid dielectrics in a gas-insulated busbar (GIB), which can cause insulation issues at the interfacing point. Both internal (puncture) and surface flashover effects will be examined through a variety of tests.
- Develop a test system that can be energised long-term in a National Grid substation in Deeside, UK, in order to monitor the performance and thermo-chemical stability of C3F7CN mixtures over time.
- Quantify the long-term system stability through post-test analysis of the gas and its by-products using gas chromatography - mass spectrometry (GC-MS). This test will also validate the material compatibility between new C3F7CN gas mixtures and solid insulating materials that have been historically used in gas-insulated equipment.