Evaluation of discharge characteristics on the triple junction for development of the Gas-Insulated Switchgear

In this study, discharge characteristics on the triple junction in GIS (Gas-Insulated Switchgear) are performed to enhance the electrical insulation performance. Firstly, the distribution of the electric field according to the contact angles is calculated with the analytical method. As a result, the case of the contact angle between 10° and 20° is calculated as the lowest electric field intensity at the triple junction. Secondly, discharge characteristics varying with contact angles of the triple junction are analyzed with the three different discharge theories such as Streamer, Paschen curve and Pedersen theory, respectively. Through the analysis, it is found that the discharge is ignited not at very close to the contact point of the triple junction which has the maximum electric field intensity, but around the contact point of the triple junction. Finally, an improved shape of the spacer having sufficient insulation performance is derived without a shield ring installation to reduce the process cost and time.