# Performance Optimization of Grounding System for Multi-Voltage Electrical Installation
## 5 Comparative Analysis of Grounding Performance
### 35 kV System (High-Voltage) Grounding  
Grounding systems in high-voltage substations, particularly those rated at 35 kV, face significant challenges due to the high-fault currents and large potential gradients involved [24]. A primary concern is ensuring efficient fault current dissipation, which prevents dangerous step and touch voltages from affecting personnel and equipment. Inhomogeneous soil conditions, including varying resistivity and moisture content, further complicate the design and maintenance of grounding systems. Moreover, the expansive surface area of substations causes ground potential rise (GPR) to extend over a broad region, necessitating careful planning to ensure safe voltage levels throughout the substation. In many industries, high-resistance grounding is designed to ensure that the system's capacitive charging current does not exceed the resistor current during a ground fault. This approach mitigates risks associated with ungrounded systems, such as overvoltages from inductive-capacitive resonance and intermittent ground faults [25]. In high-voltage mining environments, the employment of shielded cables--with higher capacitance than unshielded counterparts--adds complexity to grounding, requiring careful system design to maintain stability and safety. Table 10 shows the high-voltage substation grounding challenges for a 35 kV grounding system. Table 11 presents a comparison of fault current dissipation across various voltage levels, highlighting the corresponding ground resistance, ground potential rise (GPR), and safety compliance based on Equation (21). For 400 V (LV), fault currents range from 5 to 10 kA with ground resistance between 3 and 5 \(\Omega\), resulting in a GPR of 15,000 to 25,000 V. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Challenge** & **Description** & **Solution with Optimization Strategies** \\ \hline High-Fault Currents & High-fault currents can generate hazardous step and touch voltages. & Use multiple ground electrodes (rods, meshes) and fault current limiters to safely dissipate fault currents. \\ \hline Large Potential Gradients (GPR) & High-voltage systems create large GPR, affecting safety and equipment. & Increase electrode surface area and employ mesh or radial configurations to distribute fault current and reduce GPR. \\ \hline Soil Resistivity Variations & Soil resistivity variations lead to uneven fault current distribution, increasing GPR. & Use soil conditioning (conductive backfill) and layered electrodes to minimize resistivity impacts. \\ \hline Electromagnetic Interference (EMI) & EMI from high-voltage systems affects nearby equipment and grounding performance. & Implement shielding, proper grounding of sensitive equipment, and adequate separation to reduce EMI. \\ \hline Transient Overvoltages & Transient overvoltages from lightning or switching can overwhelm the grounding system. & Install surge arresters and transient voltage suppressors to manage overvoltages. \\ \hline Maintenance Challenges & Grounding system performance can degrade due to environmental changes. & Regular monitoring, including soil resistivity and GPR testing, and use of corrosion-resistant materials for durability. \\ \hline Substation Size and Layout & Large substation area complicates fault current dissipation and GPR management. & Optimize grounding layout with radial or mesh configurations and appropriately spaced electrodes for better current flow. \\ \hline \hline \end{tabular}
\end{table} 
Table 10: High-voltage substation grounding challenges for a 35 kV grounding system. Higher-voltage systems require low-resistance grounding due to the significantly larger fault currents they must dissipate safely [26]. As the system voltage increases, the ground potential rise (GPR) escalates, necessitating more advanced grounding strategies to mitigate potential hazards.