Aging condition assessment of cable sheath protectors based on high-order harmonic ratio of leakage current

Zinc oxide cable sheath protectors are critical devices in power systems that ensure the safety of cable power supply, and their operating status directly influences the safety of the line. However, prolonged exposure to various over voltages can lead to significant aging, resulting in performance degradation. In this context, leakage-current-based condition monitoring plays an important role in predicting the aging state of cable sheath protectors. This study employs lightning impulse aging methods to investigate the high-frequency characteristics of cable sheath protectors after impact aging, proposing a diagnostic detection indicator for aging status based on the harmonic ratio of the leakage current. Notably, this indicator showed a gradually increasing trend with the aging progression. Therefore, it can be effectively used to assess the aging status of the cable sheath protector, providing technical support for the detection of the aging status of the cable sheath protector.