Multi-particle initiated breakdown of gas mixtures inside compressed gas devices

Sayed A Ward,M A Abd Allah,Amr A Youssef

doi:10.1109/ceidp.2012.6378793

Abstract

SF 6 gas insulated switchgear plays an important role in electric power networks all over the world due to its merits as compared to traditional air insulated switchgear. According to a numerous studies, it appears very difficult that any pure gas can bring a solution to the issue of desirable insulation ability and low environmental impact, so the mixtures composed of a strongly electronegative gases with high dielectric strength such as SF 6 and ordinary gases (N 2 , CO 2 , or Air) are used to reduce the gas price and liquefaction temperature. From this point of view, various types of gas mixtures such as(5%SF 6 +5%CO 2 +90%Air), (5%SF 6 +40%CO 2 +55%Air), (5%SF 6 +80%CO 2 +15%Air), (5%SF 6 +5%N 2 +90%Air), (5%SF 6 +40%N 2 +55%Air) and (5%SF 6 +80% N 2 +15%Air) are used inside compressed gas devices to give a higher dielectric strength with lower cost and lower environmental impact. In this paper, the Finite Elements Method (FEM) is used to evaluate the electric field distribution on and around multi-contaminating filamentary wire particles. The effect of two contaminating particles which one of them is rested at ground plate and other is hovering inside the gap on the electric field values are studied. The effect of three contaminating particles which are rested at ground plate on the electric field values are also studied. The effect of gas pressure, SF 6 gas concentration in mixture, gap spacing and height between particles on the breakdown voltage calculations are also studied.

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