高压电缆缓冲层烧蚀机理、检测技术与解决方案研究进展

In recent years, buffer layer ablative failure occurs frequently in high-voltage cables with corrugated aluminum sheathed structure, which seriously affects the safe and stable operation of cables. The mechanism, detection technology and solution of buffer layer ablation have been widely concerned in the field of power cable. On the basis of describing the structure and function of buffer layer, combined with the disintegration analysis results of actual cables, the typical characteristics of ablative faults are systematically summarized from the angles of aluminum sheath, buffer layer, insulation shield layer, and main insulation layer. The mechanism of buffer layer ablation under dry and wet conditions is summarized. Under dry conditions, ablation failure is mainly caused by local current concentration caused by uneven cable force. Under humid conditions, in addition to the above mechanism, the high-resistance white powder generated by the electrochemical corrosion reaction further aggravates the current concentration phenomenon, and the Joule heat continues to accumulate, eventually causing damage to the cable structure. Based on ablative characteristics and mechanism, the applicability of various ablative defect detection techniques is discussed, including detection methods based on changes of physical signal, cable structure during ablative process and ablative products. In addition, this paper discusses the solution of buffer layer ablative failure. For the stock cable, the repair technology can be adopted to repair the fault buffer layer before the ablative damage does not hurt the insulation shield. For incremental cables, it is recommended to strictly control the composition and content of impurity ions in the buffer layer, ensure good electrical contact between the insulation shield and the aluminum sheath, or replace the existing corrugated aluminum sheath structure with a smooth aluminum sheath structure to fundamentally prevent the occurrence of ablation failures.