Influence of Bridging between Insulating Materials on the Partial Discharge Inception Voltage in Insulating Material-Air Gap-Insulating Material Electrode Systems

Abstract

A minute air gap may result in a successive partial discharge in an insulation system. Here, the partial discharge inception voltage (PDIV) in a half-pipe-type insulating material-air gap-insulating material electrode system with or without bridging between insulating materials was measured to investigate the influence of the bridging between insulating materials on the PDIV. The PDIV under the DC ramp voltage (DC-PDIV) with bridging between insulating materials using Al tape is higher than that without bridging. The DC-PDIV after cutting the bridging Al tape between insulating materials also corresponds to that without bridging. In addition, the PDIV under a surge voltage application (Surge-PDIV) is almost the same despite the bridging change. These results indicate that the inverse field due to the charge traveling via the Al tape for bridging between insulating materials relaxes the external field.