Decomposition products of 1,3,3,3-tetrafluoropropene and perfluoro-(3-methylbutan-2-one) gas mixtures in medium voltage electrical switchgear. Alternatives to SF6

In this work, binary and ternary gas mixtures of 1,3,3,3-tetrafluoropropene, HFO-1234ze(E), and perfluoro-3-methylbutan-2-one, CF3C(O)CF(CF3)2, with CO2 and synthetic air, are presented as alternatives to SF6 in medium voltage electrical equipment. They were used in four medium voltage switchgear cubicles replacing SF6 gas. After a period of time under permanent 30 kV AC voltage, gas mixtures samples were extracted and analyzed at the same day by a validated methodology based on gas chromatography coupled to mass spectrometry (MS) and thermal conductivity (TCD). CF4 (tetrafluoromethane), C2F6 (hexafluoroethane), C3F6 (hexafluoropropylene), C3HF7 (1,1,1,2,2,3,3-heptafluoropropane), CH2F2 (difluoromethane) and cis and trans-C3H2F4 (1,3,3,3-tetrafluoropropene) have been identified as decomposition products in these gas mixtures. The most abundant decomposition products identified in mixtures (C3HF7 and C3F6), water and CO content have been quantified using commercial gas mixture reference standards. The toxicity and global warming of the analyzed compounds are evaluated to determine the best mixture of those exposed in this study.