Estimation of surface breakdown voltage of solid/gas composite insulation with embedded electrode

Abstract

Solid insulated switchgear (SIS) has been developed as a substitution for medium voltage SF6 gas insulated switchgear. Its main circuits including a vacuum interrupter are coated with epoxy resin, therefore, a solid/gas insulation system is formed. For further miniaturization and higher stress design of SIS, the authors investigated on the surface insulation of the solid/gas insulation system containing an embedded electrode. In the present study, the surface breakdown voltage was estimated based on the surface discharge propagation characteristics. From the measurement of the surface flashover voltage on a dielectric against the surface distance, the relation between the surface flashover voltage and the surface distance was found to be expressed with an equation derived from the empirical equation presented by Toepler. Then, the surface breakdown voltage was estimated based on the obtained equation. The estimated values were compared with the experimental data obtained varying a parameter of the radius of the embedded electrode, thickness of the epoxy resin plate or the radius of the plate. As a result, a good correlation was obtained. Therefore, the estimation method of the surface breakdown voltage on the solid/gas insulation with embedded electrode was established.

Basic study on surface insulation design of solid/gas composite insulation system with embedded electrode

“…In the previous paper [5], the surface breakdown voltage (BDV) under impulse voltage application was found to depend on the polarity. However, lower value should be taken as the impulse BDV.…”

“…The surface breakdown takes place when both of the surface discharges reach the opposite electrodes. In the previous study [5], the surface breakdown voltage was estimated based on the propagation characteristics of the surface discharge. In the present study, the surface breakdown voltage was also calculated based on the estimation method proposed in the previous study [5].…”

“…In the previous study [5], the surface breakdown voltage was estimated based on the propagation characteristics of the surface discharge. In the present study, the surface breakdown voltage was also calculated based on the estimation method proposed in the previous study [5]. In addition, potential distribution along the surface was calculated using a software, Ansoft Maxwell (Ansoft Japan Co., Ltd.).…”

“…In the previous paper [5], the authors measured the surface discharge propagation characteristics experimentally and proposed an estimation method of BDV based on the surface discharge propagation characteristics. From the comparison between the estimated value and the measured value in [4], a good correlation was obtained.…”

“…In the present study, the surface breakdown characteristics were calculated using the estimation method proposed in the previous paper [5]. The divided voltage ratio, the radius of the embedded electrode, the enhancement factor of the surface insulation strength and the peak value of the surface breakdown voltage are examined.…”