Pressure Rise due to SF₆ Arcing and Energy Balance in a Closed Container

Abstract

From an environmental viewpoint, when carrying out internal arc tests on SF 6 -insulated power equipment, it is necessary to prevent SF 6 from being released into the atmosphere or to replace SF 6 with air in accordance with IEC standards. However, the pressure rise and the thermal effect of the hot gas exhausted during arcing when testing in air are still considerably different from those for testing in SF 6 . Thus, it is necessary to propose a specific procedure to replace SF 6 with air and to select appropriate parameters for the tests. Therefore, it is desirable to clarify the equivalent conditions causing these phenomena both experimentally and analytically. In this paper, we describe the effect of the charged gas pressure in a closed container on the pressure rise due to air and SF 6 arcing and the ratio of the arc energy to the energy contributing to the internal pressure rise (k p ) from an experimental viewpoint. Additionally, to research the energy balance resulting from SF 6 arcing in the container, the energy balance is discussed on the basis of chemical reactions, radiation, and the melting and vaporization of the electrodes. It is found that the maximum pressure rise increases for both gases upon increasing the gas pressure from 0.1 MPa to 0.4 MPa. Subsequently, good agreement with the energy balance was obtained under reasonable assumptions by taking account of the energy components related to the chemical reactions, radiation, and the melting and vaporization of the electrodes. The ratio of the radiation energy loss to the total consumption energy increased upon increasing the charged gas pressure. C⃝ 2016 Wiley Periodicals, Inc. Electr Eng Jpn, 195(3): 26-37, 2016; Published online in Wiley Online Library (wileyonlinelibrary.com).