Space charge accumulation under effects of temperature gradient and applied voltage reversal on solid dielectric DC cable

Abstract

A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of DC power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial AC XLPE power cables under an application of 80 kV DC supply at different temperature gradients and during external voltage reversal are discussed in this paper. The space charge distributions were measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material during voltage reversal. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature as space charge accumulation during polarity reversal plays an important factor on the electric field distribution within the insulation material.