CONDUCTING PARTICLES IN COMPRESSED GAS INSULATED TRANSMISSION LINE SYSTEMS

The excellent insulation properties of Sulphur Hexafluoride (SF(,6)) are the main factors for the growing interest in the application of compressed gas systems for electrical insulation in high-voltage equipment. Electrical insulation performance of gas insulated transmission line (GITL) systems is adversely affected by metallic particle contamination. The motion of such particles is essentially random in nature. The dynamics of wire and spherical particles in a coaxial system under AC voltage are studied. The numerical model of the particle movement permits an evaluation of particle trapping during commissioning.;The breakdown voltage of a contaminated gas insulated power apparatus depends upon the particle shape, size, material and the instantaneous position in the inter-electrode space. The breakdown voltage profile describes the insulation's instantaneous withstand voltage as a function of the particle position. An approach to predict the possibility of the SF(,6) gas insulation breakdown in the presence of metallic contaminants in a practical GITL system is presented.;Diagnostic tests on contaminated GITL systems are developed. The tests were done with wire particles since they approximately correspond to the type of particles encountered in practice. Both breakdown and partial discharge test results may be used as diagnostic tools in determining particle lengths in contaminated GITL systems.