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Overview
The cable sheath protection grounding box is specifically designed for 35–220 kV high-voltage cable systems. It is used for direct grounding and cross-bonding connection of three-phase cable metal sheaths, effectively protecting the outer sheath insulation from overvoltage damage and significantly improving the operational reliability of power cable lines.
This product accommodates grounding cable conductor cross-sections ranging from 120 mm² to 400 mm². Suitable for both outdoor installation and cable trench applications, it adapts well to a variety of high-voltage cable routing environments, including urban underground cable networks, substation outgoing sections, and mountainous transmission corridors.
Key Features
1. Reliable Cable Sheath Protection
The grounding box connects and protects the metal sheath of high-voltage cables, helping to reduce the risk of sheath overvoltage damage during system operation. It is particularly effective in mitigating transient overvoltages caused by switching operations, lightning strikes, or fault conditions.
2. Supports Cross-Bonding and Direct Grounding
The product supports both cross-bonding interconnection and direct grounding of three-phase cable metal sheaths. This flexibility allows cable system designers to optimize sheath current distribution, reduce circulating currents, and minimize sheath losses for long-distance transmission lines.
3. Durable Structural Design
The outer enclosure and main internal structure are welded using high-grade stainless steel, ensuring long-term durability for outdoor use even in corrosive or humid environments. All insulating components are treated for moisture resistance, improving operational reliability across diverse environmental conditions.
4. High-Conductivity Copper Grounding Connection
The grounding busbar and connection terminals are made of high-conductivity copper, ensuring stable grounding performance and low contact resistance in high-voltage cable applications. Tin-plated copper options are available for enhanced corrosion resistance.
5. Easy Installation and Maintenance
All internal assemblies are secured with bolt connections, making installation convenient and also allowing easy disconnection between the cable metal sheath and the ground wire during preventive testing or fault diagnosis. The front cover can be opened without special tools, facilitating routine inspection.
Working Principle
The core component of the grounding box is the cable sheath protector, which consists of oxidation-resistant nonlinear resistance elements (typically zinc oxide varistors). Under normal operating conditions, the resistance element remains in a high-resistance state, effectively isolating the sheath from the ground for cross-bonded sections. When an overvoltage wave occurs (e.g., due to a lightning strike or switching surge), the resistance element rapidly switches to a low-resistance state, clamping the voltage across the protector within a safe range.
This mechanism helps effectively protect the outer sheath insulation of the cable, preventing damage caused by overvoltage and extending the service life of the high-voltage cable system.
| Item | Specification |
|---|---|
| Application Voltage Class | 35–220kV high-voltage cable systems |
| Grounding Cable Conductor Cross-Section | 120–400mm² |
| Ambient Temperature | -40℃ to 40℃ |
| Altitude | Not exceeding 1800 meters |
| Power Frequency | 50Hz |
| Installation Environment | Outdoor or cable trench |
