Study on the Electrical Conductivity Characteristics of Semi-Conductive Buffer Layer for High-Voltage Cables

Discharge-induced ablation failures in the buffer layers of corrugated aluminum-sheathed XLPE cables have been observed in both domestic and international applications, posing significant threats to the safe and stable operation of cables. The semiconductive water-blocking buffer layer, situated between the outer shielding and the corrugated aluminum sheath, serves multiple critical functions including fault current conduction, mechanical stress buffering, water resistance, and thermal insulation. Electrical conductivity is one of the key performance indicators of the buffer layer, and its conductive properties are highly susceptible to internal environmental factors such as temperature, humidity, and pressure. However, current research on the influence of environmental factors has primarily focused on conventional buffer layer materials, with limited studies on semiconductive butyl rubber tapes. Furthermore, potential structural improvements to mitigate discharge-induced ablation failures remain unexplored. This study presents a comparative analysis of the effects of environmental factors on two types of buffer layer materials. The experimental results reveal the following: The semiconductive polyester non-woven water-blocking fabric exhibits a negative temperature coefficient, but with significant spatial variations in resistivity distribution. In contrast, the semiconductive butyl rubber tape demonstrates a positive temperature coefficient and maintains uniform resistivity distribution. The semiconductive polyester non-woven fabric is inferior to the butyl rubber tape in terms of water resistance. Elevated temperatures, increased pressure, and moisture absorption can all lead to a rise in the volume resistivity of the buffer layer, potentially exceeding standard thresholds and thereby triggering discharge-induced ablation failures.