A vast network of high-voltage cables runs through cable trenches, tunnels, and utility tunnels, forming the backbone of regional power transmission. Compared to overhead lines, underground cables take up less space and are less susceptible to weather conditions; however, they also present significant challenges. Early signs of faults in underground cable routes are often hidden, and once a problem arises, troubleshooting is time-consuming and labor-intensive. Among the various hidden defects in cables, abnormal loop currents in the metal sheath have long been a persistent headache for frontline operations and maintenance personnel.
When a single-core cable is in operation, the alternating current flowing through the conductor generates an alternating magnetic field, which induces an electromotive force in the metal shield. If the outer sheath is damaged, water enters the cross-connection grounding box, or the grounding wire becomes loose or is even stolen, a closed circuit is formed, resulting in a continuous shield grounding loop current. These changes exhibit no visible signs and cannot be detected with the naked eye. Traditional inspection methods rely solely on periodically opening the cover for spot checks, yielding only instantaneous measurement data at specific points. Situations such as slowly drifting loop currents or sudden spikes are easily overlooked, and by the time problems are discovered, damage has often already accumulated.
Dinsee Smart Technology Co., Ltd. has been deeply involved in the field of condition monitoring for power transmission, distribution, substations, and cables for many years. Its products have been shortlisted for provincial and national framework projects on multiple occasions, have won numerous bids, and have been deployed on a large scale in many cities. For example, to address on-site challenges related to cable sheath loop current monitoring, the company has launched an online monitoring device for cable sheath ground loop currents, available in multiple versions. It offers customized products tailored to specific customer applications and has accumulated a vast amount of real-world operational data across different regions and under various cable corridor conditions.
The design concept of the online monitoring device for cable sheath ground loop currents is tailored to the practical needs of on-site cable operation and maintenance:
1. Real-time collection of multiple parameters, covering typical basic parameters
The loop current transformer is mounted on the cable sheath grounding conductor. By collecting data such as sheath grounding loop current and induced sheath voltage, it measures the magnitude and changes in the loop current in real time. It can identify common defects such as sheath damage, failure of the cross-connection system, and broken grounding conductors, and comprehensively records trends in parameter changes.
2. High-Immunity Sensing Solutions
By using a high-precision split-core current sensor, there is no need to disconnect the ground wire or shut down power for installation, and there is no need to worry about the complexity of the electromagnetic environment in the on-site cable duct.
3. Multiple power supply modes to accommodate various installation locations
Supports power harvesting via CT induction and photovoltaic energy; in cable trenches without sunlight, power is harvested from the cable’s own magnetic field; outdoor grounding box locations can also be equipped with an optional photovoltaic power supply solution.
4. View Status Remotely
Data transmission supports both wireless and wired methods, with monitoring data uploaded in real time to the monitoring platform. As soon as potential hazards—such as loop current exceeding limits, sudden current changes, or grounding wire abnormalities—are detected, alerts are immediately sent. Operations and maintenance personnel can view real-time readings and historical data for each monitoring point from the backend, eliminating the need to repeatedly descend into cable trenches and allowing them to remotely monitor the operational status of the entire cable line’s sheath.
5. Industrial-grade housing designed to withstand harsh underground environments
The equipment housing features a high protection rating and is moisture-proof, waterproof, and corrosion-resistant, making it suitable for harsh operating conditions such as standing water in cable trenches and large temperature fluctuations in tunnels.
Underground cables are the invisible lifelines of urban power supply, and sheath ground loop current monitoring serves as the health monitoring nodes for these lifelines. Dingxin Smart’s sheath ground loop current monitoring products, backed by successful bids in multiple provincial and regional networks as well as extensive implementation experience in prefectural and municipal-level applications, have been refined through numerous field conditions and are now technically mature and stable. As the power grid’s digital transformation progresses, these solutions continuously address gaps in cable condition monitoring, enable early detection of hidden defects in cable sheaths, reduce the risk of sudden cable failures and power outages, and provide reliable support for the safe operation of underground high-voltage cables.
