A Consideration on the Residual AC Breakdown Voltage of Immersed Dry-Cured XLPE Power Cables under Accelerated Aging Test

Abstract

This paper describes the change of AC breakdown voltages of 6.6kV dry-cured XLPE cables during the immersed accelerated test. The cause of the reduction of the breakdown voltages was investigated. The accelerated test was carried out by applying 6.9kV of 1kHz at room temperature with the conductor strands and insulation shields kept constantly moist. It was found that the breakdown voltage decreased to about half of the initial breakdown voltage until 3 months aging. This decrease was found to be mainly caused by the moisture permeating the cables during the accelerated test. After 3 months, the breakdown voltage decreased due to bow-tie trees which touched inner or outer semi-conductive shields.