Research on Fault Diagnosis Method for Cable Shielding Layer Based on Main Core Current Proportionality and Terminal Voltage Analysis

With the rapid development of high-speed railways and urban rail transit, the safe operation of traction power supply system cables is facing higher requirements. This article proposes a cable shielding layer fault diagnosis method based on the proportional relationship between the main core current and the shielding layer grounding current, as well as the terminal protector terminal voltage variation, using the cable online monitoring system of Zhongshan Station and Guangzhou South Traction Substation on the Guangzhou-Zhuhai Intercity Railway as the background. By analyzing the current ratio and voltage variation of cables under normal and fault conditions, combined with industrial Internet of Things technology, real-time monitoring and fault diagnosis of cable operation status can be achieved. Practical engineering applications have shown that this method has high accuracy in identifying specific faults such as open circuit and multi-point grounding in cable shielding layers, and can significantly improve cable operation and maintenance efficiency and reliability.