System Architecture & Functions
The Cable Online Monitoring System integrates Partial Discharge (PD) monitoring and sheath circulating current monitoring to provide comprehensive and intelligent awareness of high-voltage cable operating conditions.
Partial Discharge Monitoring:
Equipped with Intelligent High-Frequency Current Transformers (HFCTs), the system adopts broadband detection technology (1–30 MHz) to accurately capture high-frequency discharge signals from cable bodies and joints. With built-in AI algorithms, it automatically identifies typical insulation defects such as corona discharge and surface discharge, enabling early warning of insulation degradation risks.
Sheath Circulating Current Monitoring:
Using intelligent sheath current sensors, the system continuously records sheath grounding current magnitude and directional variations. By analyzing multi-loop synchronous data, it detects sheath insulation breakdown, multi-point grounding faults, and sudden current amplitude changes (±1% accuracy), preventing sheath overheating and mitigating risks of cable aging or external damage.
Integrated Data Management:
The system supports multi-source data fusion, offering real-time alarms, historical trend analysis, and health index evaluation. It is compatible with fiber-optic and wireless transmission, and seamlessly integrates into power IoT platforms.
This solution meets IEC 60502 and GB/T 12706 standards, making it ideal for smart O&M applications in high-voltage cable tunnels, urban power grids, and renewable energy substations—helping utilities achieve “visible status, controllable risk, proactive maintenance.”
1. Partial Discharge (PD) Online Monitoring
The HFCT sensor operates on a non-intrusive principle with no direct electrical connection to the measured current loop. When insulation defects exist inside a cable, PD pulses generated under high-voltage AC fields propagate along the cable body or grounding line. Installed HFCT sensors capture these high-frequency signals for real-time PD monitoring.
Collected PD data is transmitted via LoRa wireless to access nodes for preprocessing, and then uploaded to the central monitoring platform through 4G or Ethernet. The AI-based diagnostic system identifies insulation anomalies and discharge-related faults, providing early warnings for potential joint failures.
1.1 Main PD Monitoring Device
HMJ1010-HFCT Intelligent High-Frequency Current Sensor
- Application: Cable joints, switchgear/GIS grounding cables
- Communication: LoRa, RS485
- Installation: Clamp-on type
| Item | Specification |
| Frequency Range | 0.5–30 MHz |
| Measurement Range | 0–70 dB |
| Bandwidth | ≥2 MHz |
| Sensor Size | Inner Diameter ≈ 56 mm (customizable) |
| Transfer Impedance | ≥6.5 mV/mA |
| Sensitivity | Minimum detectable PD level ≤ 50 pC |
| Communication | Wireless: LoRa / Wired: RS485 |
| Power Supply | Wireless: Built-in lithium battery |
| Wired: DC 24V | |
| Operating Temperature | -40°C to +85°C |
| Operating Humidity | 5%–95% RH |
1.2 Field Deployment of PD Monitoring
2 Sheath Circulating Current Online Monitoring
The sheath current monitoring subsystem consists of a sheath current collector and an intelligent sheath current sensor, installed on the cable sheath grounding line. It measures sheath leakage currents and transmits real-time data to access nodes via RS485, which is then uploaded to the AI management platform.
By continuously analyzing sheath current amplitude and phase, the system can detect multi-point grounding, sheath insulation faults, or sudden leakage current increases caused by cable failures. Alarm signals are immediately sent to the control center, ensuring timely fault response and enhancing cable network stability.
2.1 Main Sheath Current Monitoring Device
Intelligent Sheath Circulating Current Sensor
- Application: Cable joints, grounding leads, switchgear/GIS grounding cables
- Communication: Coaxial cable, RS485
- Installation: Split-core circular sensor design; customizable inner diameter to fit different cable sizes
| Product Type | Item Name | Technical Parameters |
| Sheath Circulation Sensor | Measurement Range | 0 – 200A |
| Resolution | 0.1A | |
| Maximum Error | ±1A | |
| Accuracy | Class 0.5 | |
| Frequency | 50Hz | |
| Protection Level | IP68 |
2.2 Field Deployment of Sheath Current Monitoring
