Operational Risks Of Surge Arresters And Grounding Optimization Schemes In High Soil Resistivity Environments

In mountainous areas, Gobi deserts, or rocky terrain with high soil resistivity, the installation of grounding grids for power distribution lines and substation equipment faces severe challenges. For 11kv surge arrester equipment, the magnitude of the grounding resistance is directly related to the smoothness of lightning current discharge. When a lightning strike occurs, if the grounding resistance is too high, the lightning current cannot flow into the ground quickly, which will cause the 120 kv lightning arrester residual voltage to rise. This phenomenon not only weakens the ability to control overvoltage, but may also trigger a "retaliation" against electrical equipment. In severe cases, it can even cause the 12kv surge arrester equipment itself to explode or the insulator string to break down, threatening the safe operation of the line.

Technical Causes and Risks of Excessive Grounding Resistance

The main reason for the excessive grounding resistance of equipment 132 kv lightning arrester is the constraint of geological conditions. In areas with high soil resistivity, the current dissipation efficiency of conventional grounding electrodes is extremely low, and the power frequency grounding resistance is often much higher than the value required by regulations (e.g., some standards require the grounding resistance of the 132kv lightning arrester grounding point of overhead lines to be no more than 10Ω, or even a higher standard of 5Ω). This high-impedance path causes a very high potential rise to occur on the grounding device when the 132kv surge arrester operates. This potential rise can creep along the grounding wire into the equipment casing or secondary circuit, creating a dangerous overvoltage that directly threatens operator safety and the stable operation of microprocessor-based relay protection devices.

Grounding Retrofit Strategies Based on Long-Term Resistance Reduction

To address the challenges posed by high soil resistivity, single resistance reduction measures often have limited effectiveness, necessitating a comprehensive grounding retrofit solution.

Extended Grounding and Deep Well Blasting Technology

By laying auxiliary grounding grids in areas with relatively good geological conditions or relatively low soil resistivity and connecting them to the main grounding grid via multiple connecting lines, the current dissipation area can be effectively expanded. For rocky areas with thin overburden, deep well blasting pressure grouting can be used. This method involves drilling through the surface rock, creating fissures within the hole, and then pumping in a resistance-reducing agent with conductive and moisture-retaining properties, thereby establishing a deep current dissipation channel and significantly reducing grounding impedance.