Study on particle-induced corona discharge in Insulation Systems

Gas Insulation System (GIS) is in popular use because of its high reliability and recovery ability. Existing particles in GIS deteriorate the GIS performance due to their higher dielectric constant or conductivity than the gas medium. The objective of study is to investigate characteristic of corona discharge induced by particles of different shapes. In our experiments, the particles were set stand on the lower electrode in a parallel electrode system. The corona discharge was detected by R_m = 50 Ω or 500 Ω resistor. The corona inception voltage U_i was calculated in the work to compare with the experimental results. The calculated U_i is highest for the rounded-end particle, and lowest for the very-sharp end particle. U_i is lower when the particle tip was sharper. Using the different R_m values did not give so much difference for the U_i, PD charge, and breakdown voltage U_b. The calculated U_i was higher than but followed the tendency of the measured one. In addition, the PD charges and number of pulses also followed the same tendency as U_i. The PD charges were found to vary approximately linearly with the particle charges calculated by the numerical simulation. The breakdown voltage was close to each other for all particles. The tip of particles did not affect strongly on breakdown voltage. The difference between U_b and U_i was highest for the very-sharp end particle, and lowest for the rounded-end particle.