Detection and analysis of spark discharge products of C5F10O by electron attachment mass spectrometry

Abstract

C5F10O has the potential to replace SF6 as an insulation gas in switchgears due to its high breakdown field strength and low global warming potential. However, as a newly synthesized gas, the chemical characteristics of C5F10O are not well known. In particular, the discharge products of C5F10O are not clear, which limits its insulating capability evaluation in long-term use, and further hinders the development of a gas sensor to monitor the insulation deterioration of C5F10O-containing switchgears. In this paper, electron attachment mass spectrometry (MS) was proposed to detect the decomposed products of C5F10O under pulsed spark discharge condition. It was found that the ionization source of the MS had an optimal electron energy of 2 eV to avoid decomposing the gas molecules to be detected while having a high detection sensitivity. The detected discharge products mainly included CF4, C2F4, C3F6, C3HF5, C3F8, C3HF7, C4F10, C5F10, C6F12, C3F4O and C2F6O, while CF4, C3HF5, C3HF7, C5F10, C6F12, C3F4O and C2F6O were not detected using GCMS. Based on the nonionization measurement, the decomposition mechanism was deduced. Also, it was found that the densities of some products, such as C3F6, C3F8, C4F10 were increasing with the discharge voltage and the number of discharge pulses, implying that these species might be used as indicators for the discharge accumulation effects such as the insulation deterioration of switchgears.