Repair of defects in buffer layer of high voltage cable based on additive liquid silicone rubber material

Abstract

In recent years, the issue of defects in the buffer layers of high-voltage cables has garnered significant attention due to their widespread occurrence and the substantial potential damages they pose. Although progress has been made in understanding the mechanisms behind these defects and in developing detection methods, effective repair solutions remain limited. This study addresses this challenge by proposing a novel repair material: a two-component, additive liquid silicone rubber-based compound that utilises vinyl silicone oil as its base. The electrical, thermal, and mechanical properties of the cured silicone-based repair fluid are thoroughly analysed. To evaluate its effectiveness, an experimental platform was constructed using a 17-m-long, 110 kV retired cable with known buffer layer defects. A specialised injection process was developed to facilitate the application of the repair fluid. The thermal characteristics, buffer layer voltage distribution, and partial discharge behaviour of the defective cable were analysed both before and after the repair. The results indicate that following the repair, the cable's heat dissipation capacity under full load increased by 6.25%. Additionally, the buffer layer voltage at the rated voltage (U₀) decreased from 1.97 to 0.34 V, representing an 82.74% reduction. Notably, no partial discharge signals exceeding background noise were detected post-repair. This study demonstrates the effectiveness of the addition-cure liquid silicone rubber-based semi-conductive material in repairing cable buffer layer defects and provides valuable experimental support for its practical application in engineering.