Ground potential rise is caused by transient high potentials resulting from lightning current entering the ground. When lightning strikes a building's lightning rod or the nearby ground, thousands to hundreds of thousands of amperes of lightning current are discharged through the grounding system. Due to the resistance and inductance of the grounding system, according to U=IR+L·di/dt, the potential of the entire grounding system rises sharply by tens to hundreds of kilovolts in a very short time.

Main hazards:

Reverse flashover: The elevated ground potential discharges along the incoming lines (power lines, signal lines) to distant low-potential points, breaking down the insulation of the lines, and allowing the lightning current to intrude into the equipment in reverse.

Potential difference between systems: A large potential difference can be generated between independently grounded equipment within a building and the main grounding system, leading to insulation breakdown of the equipment.

SPD Overload: The actual voltage applied across the SPD far exceeds its designed voltage tolerance, causing damage to the surge protector.

Core protection principles:

Equipotential bonding: This involves connecting all metal conductors and grounding systems within a building using equipotential bonding strips to create an electrically unified system, ensuring simultaneous potential rise and eliminating dangerous potential differences.

Coordinated SPD protection: Install matching SPDs at various line entry points to provide a controlled discharge path for lightning currents.

Grounding grid optimization: Using a ring/mesh grounding system reduces surge impedance and improves the dissipation of high-frequency lightning currents.

This protection system minimizes the dangers of ground potential rise through the concept of "equalizing potential and controlled discharge."