Analysis Of Key Elements In Transformer Grounding Systems

The grounding potential of the neutral point must be strictly controlled within safe thresholds. Excessively high potentials pose a risk of insulation breakdown. Standards stipulate that the neutral point of distribution transformers must be reliably grounded, and equipotential bonding should be implemented to ensure potential equilibrium across all nodes in the system.

2.1 Solid Grounding

Suitable for high-voltage systems of 110kV and above, it effectively limits overvoltage and ensures system stability.

2.2 Grounding via Arc Suppression Coil

Ideal for 6-35kV distribution networks, this method automatically compensates for grounding currents, reducing the impact of ground faults on the system.

2.3 Resistance Grounding

Enables precise control of fault currents and is commonly used in critical industrial sites with high requirements for power supply reliability.

3.1 Resistance Standards

The grounding resistance of distribution transformers should be ≤4Ω.

Independent grounding electrodes should have a resistance ≤10Ω.

3.2 Composite Grounding Grid Correction

When using composite grounding grids, seasonal coefficient corrections must be considered to account for environmental impacts on resistance values.

3.3 Testing Requirements

Dedicated grounding resistance testers should be used quarterly to verify compliance with resistance standards.

4.1 Ground Electrode Installation

Ground electrodes must be buried below the frozen soil layer and kept away from corrosion sources to ensure long-term stability and durability of the grounding system.

4.2 Conductor Cross-Section Requirements

The cross-sectional area of grounding conductors must meet thermal stability requirements for short-circuit currents, preventing damage from overheating during faults.

4.3 Connection Technology

All connection points must use exothermic welding or specialized clamps to ensure secure fastening and minimize contact resistance.