Substation Earthing Design – Protecting Infrastructure and Lives

What Is Substation Earthing and Why It Matters

A well-designed earthing system:

• Dissipates fault currents into the soil
• Stabilizes system voltage during abnormal events
• Limits touch & step voltages to safe thresholds
• Controls transferred potentials through buried metallic paths
• Mitigates VFTOs (Very Fast Transient Overvoltages) in GIS

Without compliance, step voltages can exceed 80 V and touch voltages can rise above 50 V—levels that pose lethal shock hazards.

Critical Design Considerations

Fault Current Duration & Path

Longer faults demand stricter voltage limits to reduce human risk exposure.

Soil Characteristics

Resistivity varies with moisture, temperature, and layering; solutions include vertical rods, ground beds, or soil enhancement.

Transferred Potentials

Underground pipes or cable shields can conduct fault currents into nearby structures, affecting public safety.

GIS Station Risks

High-frequency VFTOs during SF₆ disconnector operations can stress insulation and electronics.

Mitigation Methods

Equipotential bonding grids, insulated barriers, shielding electrodes, and surface treatments (e.g., gravel) reduce hazard voltages.

How Keentel Ensures Compliance & Safety

We use advanced tools and site-specific strategies:

1. Detailed Soil Resistivity Surveys (Wenner, Schlumberger, Dipole–Dipole)
2. CDEGS-Based Modeling for step/touch voltage and ground potential rise
3. Touch & Step Voltage Mapping against EN 50522 and IEEE 80 criteria
4. VFTO Analysis for compact GIS installations per IEC 62271-100
5. Hazard Voltage Analysis Reports for audit readiness and safety compliance
   
   

These measures integrate electrical safety compliance with critical infrastructure protection.

FAQs | Substation Earthing & Dangerous Voltages

Case Studies: Real-World Earthing Solutions

Case Study 1: Urban GIS Substation

• Project: 110 kV GIS within a commercial block
• Challenge: Transferred voltages via shared infrastructure
• Solution: 3D simulation of buried paths, >100 m separation of earthing grids, insulated GIS enclosures
• Result: External touch voltages reduced below 50 V

Case Study 2: Remote Wind-Farm Substation

• Project: HV AIS station on high-resistivity terrain
• Challenge: Poor fault dissipation in dry soil
• Solution: Vertical rod clusters, layered resistivity modeling, artificial ground beds, gravel surfacing
• Result: Step/touch voltages safely within EN 50522 limits

Case Study 3: GIS VFTO Mitigation in Compact Substation

• Project: 220 kV GIS near a water treatment plant
• Challenge: VFTO-induced equipment malfunctions
• Solution: Compact grounding mesh, direct enclosure bonding, shield electrodes, isolated CT returns
• Result: VFTO compliance tests passed; no control-system issues

Our Related Services You Can Explore

Substation Design Services

End-to-end primary and secondary substation engineering—including detailed earthing grid layouts, grounding conductor sizing, and safety studies—to ensure your HV/MV substation meets all EN 50522, IEEE Std 80, and local code requirements.

EHV, HV & MV Power System Studies

Comprehensive fault-current, load-flow, and grounding‐grid analyses (using PSCAD, PSSE, ETAP, and CDEGS) that validate your grounding design, step/touch voltages, and transient performance under worst-case fault conditions.

Ready to Secure Your Substation Earthing?

Partner with Keentel Engineering to safeguard your people and infrastructure with code-compliant, scientifically validated grounding designs.