Assesment of Dielectric Bevaviour of Sf₆/N₂ Gas Mixtures In The Presence Of Metallic Particle Contamination in A Common Enclosure Gas Insulated Busduct

Sulphur hexafluoride (SF₆) gas currently used as an insulating medium in the gas insulated switchgear has many advantages of chemical stability non flammability, non-toxicity and non explosiveness. However, SF₆ is not easily decomposed in nature by its chemical stability. The possible effect on the environment has become a burning topic as “GREEN HOUSE” gas. Among the environmentally benign gases, alternative to SF⁶ gas, the SF⁶- N² gas mixtures is regarded as one of the most attractive gases for the same setup used for SF⁶, because of the synergetic effect in electrical insulation performance. Failures in GIS are mainly due to the presence of various conducting contaminants in the form of loose particles which are produced by the abrasions between components during assembly and operation. The presence of metallic contaminant in compressed GIS is a major threat when operated at higher fields. If the effect of these can be reduced, the reliability of GIS can be improved. This paper aims at formulation of basic equations that govern the movement of the metallic particles of different shapes in a 3-ph Gas Insulated Bus duct (GIB). Simulation considers the effect of electric field on the movement of metallic contaminant in pure SF⁶ gas and mixture of gases (SF⁶/N²) in different proportions and results have been presented and analyzed.