Study on Particle-Induced Corona Discharge in Insulation Systems

Abstract

Gas insulated systems are in popular use for operational reliability, safety, and compactness. Metallic particles in gas insulation systems are a common source of failures. The objective of this study is to investigate the characteristic of corona discharge induced by particles having different ending shapes with various gaps between the particle and the electrode. The experiments are conducted with two configurations, (i) particles having rounded, sharp, very-sharp tips or spheroidal particle are set to stand in contact with the grounded electrode, (ii) particle having sharp or flat tips are set to float above the, grounded electrode by small gaps. An analysis is also applied to study. The corona inception voltage is estimated by using streamer breakdown criteria. For the experiment on the standing particles, the corona inception voltage is higher with sharper particle tip; and partial discharge current magnitude and charge tend to be higher or larger for higher corona inception voltage. The partial discharge charge follows the tendency of the measured values for the standing particles. For the experiment on the floating particles, the particles having flat upper tip yield direct breakdown at 0.25 to 1 mm, and corona discharge at larger gap from 1.5 to 2 mm. The corona inception voltage, current magnitude and charge depend on the gap lengths and the tip shapes of the particles.