The effects of semicon on space charge behavior under different temperature conditions for HVDC cable insulation

One of the major concerns related to HVDC applications is the presence of space charge within the dielectrics, which distorts the electric field distribution and contributes to accelerated ageing and consequent failure of the cable insulation. In this paper, an attempt is made to explore the space charge characteristics using different electrode materials and temperature conditions to highlight the variation in space charge formation and distribution in the system using pulsed electro acoustic (PEA) technique. To simulate a real cable manufacturing process, XLPE insulation was sandwiched between two layers of thermal bonded semicon material. The experimental results revealed that the semiconductive materials has a greater influence on the space charge formation. It was found the electrode materials play a vital role in determining the charge distribution in the insulation and significant dependence on the electrode materials under the same applied stress and temperature conditions. Thermal bonded semicon samples have a stronger charge injection and greater charge amount within the bulk and high temperature can greatly increase the charge mobility for both polarities as well as enhances charge injection. These findings are discussed in conjunction with unbonded sample (conventional setup) for the space charge measurements.