Surface Charging in Different Gaseous Medium in Extremely Nonuniform Electric Fields

The introduction of gaseous insulation in electrical systems played a major role in the evolution of the power industry. It made the systems compact in size and stable during operation. The discharge characteristics of dry air, N2, and CO2 have been extensively studied in the literature, whereas the dc/ac surface charging characteristics in the presence of these gases require further investigation. The present study provides notable insights into the dc/ac surface charging of insulators in dry air, N2, and CO2 due to discharges in extremely nonuniform fields. The corona current pulse and discharge images were also captured to analyze the discharge behavior. The results obtained have been compared with sulfur hexafluoride (SF6) gas. Surface charging is mainly governed by the source type and the medium (gas) where the discharge occurs. Of all the gases studied, CO2 and SF6 perform similarly, exhibiting less discharge but increased surface charge deposition.