The influence of water-blocking powder on corrosion products and ablation failures of cable buffer layers

To clarify the influence of Water-blocking Powder (WBP) on buffer layer ablation failure in cables, this study investigated two types of buffer layers, with and without WBP. The full failure process was reproduced through electrical parameter measurements, moisture intrusion corrosion experiments, and partial discharge tests, and was further analyzed in combination with microscopic characterization, electrochemical analysis, ablation gas analysis, and electro-thermal field coupled simulation. In this way, the performance differences and failure behavior of the two buffer-layer systems were systematically compared. The results show that moisture intrusion is a common trigger for the deterioration of the electrical properties of both buffer layers, but their failure characteristics differ markedly: the WBP-free buffer layer is more prone to corrosion, whereas the WBP-containing buffer layer is more sensitive to partial discharge, exhibiting a larger reduction in partial discharge inception voltage and a higher ablation risk. The electrochemical results further indicate that NaPA regulates the charge-transfer process at the buffer layer–aluminum sheath interface through local alkalization, interfacial adsorption, and complexation. ablation gas analysis shows that WBP does not alter the core components of the characteristic fault gases, thereby preserving the applicability of existing fault-detection methods. The simulation results further confirm that the superposition of an air gap and white corrosion products significantly aggravates electric-field distortion and temperature-rise effects, thereby accelerating ablation development. This study clarifies the key distinction between the two buffer-layer systems, these findings provide theoretical support and engineering reference for the optimization of cable buffer layer selection and fault early warning.