Exploring the Decomposition Products of 1,3,3,3Tetrafluoropropene and Perfluoro-(3-methylbutan-2-one) Gas Mixtures in Medium -Voltage Electrical Switchgear as Alternatives to SF6

Abstract

In this work, binary and ternary gas mixtures of 1,3,3,3-tetrafluoropropene, HF0234ze(E), and perfluoro-(3-methylbutan-2-one), CF3C(0)CF(CF3)2 with CO, 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, and after a period of time, under permanent 30 kV AC voltage, gas mixture samples were extracted and analyzed on the same day using a validated methodology' based on gas chromatography (GC) coupled to mass spectrometry (MS) and thermal conductivity (TCD). CF4 (tetrafluoromethane), C2F6 (hexafluoroethane), C,F6 (hexafluoropropylene), C3FIF7 (1,1,1,2,2,3,3-heptafluoropropane), CHF, (difluoromethane), and the cis and trans-C3H2F4 (1,3,3,3 tetrafluoropropene) have been identified as decomposition products in these gas mixtures. In addition, a quantity of water has been observed, as well as CO in one of the cubicles. The most abundant decomposition products identified in gas mixture samples (C3HF7 and C3F6) together with 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 most adequate gas mixture among those studied as a candidate to substitute SF6.