高压电缆缓冲层烧蚀缺陷的超声检测实验

高压电缆缓冲层烧蚀故障是近年来频发的电缆故障类型，然而目前的烧蚀缺陷检测手段难以满足存量电缆的检测需求。本文首次研究了基于铝护套内表面粗糙度的高压电缆缓冲层烧蚀缺陷的超声检测方法。首先，开展了潮湿条件下的缓冲层烧蚀模拟实验，并对烧蚀后的铝片开展了激光共聚焦显微镜测试以及电化学阻抗谱分析，发现随着烧蚀时间的增加，铝片的表面粗糙度逐渐增大，同时铝片表面的腐蚀程度逐渐加深，对应的缓冲层烧蚀缺陷逐渐加重，表明铝片的表面粗糙度与潮湿条件下缓冲层的烧蚀程度存在关联。其次，对烧蚀后的铝片开展了超声检测实验，并通过相邻超声回波信号的幅值比推算出了铝片腐蚀面的粗糙度，与实验测得的粗糙度具有相同的变化趋势。本文结果表明超声检测可用于检测缓冲层烧蚀缺陷的严重程度，为高压电缆缓冲层烧蚀缺陷超声检测方法的应用奠定了研究基础。

Experiments on the Ultrasonic Detection Method of Ablation Defects in High Voltage Cable Buffer Layer

The ablation fault of buffer layers in high-voltage cables is a frequent type of cable fault in recent years. However, current detection methods for ablation defects cannot meet the detection requirements of existing cables. In this paper, the ultrasonic detection method for the buffer layer ablation defects in high voltage cables based on the surface roughness of aluminum sheath is studied for the first time. First, simulated buffer layer ablation experiments under humid conditions were carried out, and the laser confocal microscopy and electrochemical impedance spectroscopy analysis were carried out on the ablated aluminum specimens. It is found that with the increase of ablation time, the surface roughness of aluminum specimens gradually increases, and the surface corrosion degree of aluminum specimens gradually deepens, corresponding to the aggravated ablation defects of buff-er layers, which indicates that the surface roughness of aluminum specimens could be correlated with the ablation degree of buffer layers under the moisture conditions. Secondly, ultrasonic testing experiments were carried out on the ablated aluminum specimens, and the roughness of the corroded surfaces of aluminum specimens could be calculated from the amplitude ratio of adjacent ultrasonic echo signals. The calculated results show the same variation trend as the measured roughness in the experiment. The results in this study indicate that the ultrasonic tests could be used to detect the severity of buffer layer ablation defects, providing the research basis for the ultrasonic detection method of ablation defects in the buffer layer of high-voltage cables.