Effects of Impurity Anions in the Buffer Layer on Electrochemical Corrosion and Ablation of High-Voltage Cables

Ablation faults of high-voltage cables have become a great safety challenge, with electrochemical corrosion playing an important role in ablation faults. Impurity ions have been found in the buffer layer (BFL), however, the mechanism of the effect of impurity ions on electrochemical corrosion and ablation is still lacking in knowledge. In this paper, the influence of impurity anions in BFL on electrochemical corrosion and ablation was investigated. It is found that electrochemical corrosion is hindered in the pure BLF and it is difficult to be ablated. But the BFL with impurity ions is susceptible to persistent electrochemical corrosion and ablation. This is due to the fact that impurity ions including Cl-, NO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>-, and SO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub><sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>-destroy the adsorption barrier layer formed by sodium polyacrylate (NaPA) on the aluminum surface through competitive adsorption. In particular, pitting damage of Cl-to the passivation layer further accelerates the corrosion, so that its effect is more significant. The result of this paper shows that the control of impurity ions in the BFL is critical in the combating of cable ablation.