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.