Investigation on insulation properties of HFO-1336mzz(E) and N₂/CO₂ mixtures as SF₆ substitutes in gas-insulated electrical applications

The emissions of SF₆ have been restricted owing to 3400 years of atmospheric lifetime and high global warming potential (GWP) as an insulating gas in gas-insulated electrical equipment. In this study, HFO-1336mzz(E) and N₂/CO₂ mixtures are proposed as SF₆ substitutes for their short atmospheric lifetime, low GWP and superior insulation performance. The GWP of HFO-1336mzz(E) is only 18 and its atmospheric lifetime is days to weeks. The breakdown voltage of 25% HFO-1336mzz(E) and N₂/CO₂ mixtures is about 85% that of pure SF₆ under alternating current. The self-recovery ability of HFO-1336mzz(E) and CO₂ mixtures is superior to that of HFO-1336mzz(E) and N₂ mixtures. The decomposition characteristic of HFO-1336mzz(E) shows that a tiny amount of its gas might initiate a carbonisation reaction to form carbon after multiple breakdown tests, which is verified by observations using energy dispersive X-rays spectroscopy and scanning electron microscope. The acute toxicity test of HFO-1336mzz(E) indicates that the gas is non-toxic. The results show that HFO-1336mzz(E) and N₂/CO₂ mixtures are potential substitutes for SF₆ in electrical applications.