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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Which type of earthing is done in a high voltage system or equipment?
Ray Earthing
Pipe earthing
Coil earthing
Strip
Ray Earthing
Quick Summary: Ray earthing (also known as Star Earthing or Plate/Pipe with additional conductors) is specifically designed for high-voltage systems and power stations. It involves burying multiple metallic conductors in a radial pattern around the grounding point to minimize ground resistance and handle high-magnitude fault currents effectively.
Ray earthing (also known as Star Earthing or Plate/Pipe with additional conductors) is specifically designed for high-voltage systems and power stations. It involves burying multiple metallic conductors in a radial pattern around the grounding point to minimize ground resistance and handle high-magnitude fault currents effectively.
Rg≈2πLρln(d4L) — Simplified resistance estimation for an earth electrode where ρ is soil resistivity, L is length, and d is diameter.
In high-voltage environments, fault currents can reach several kiloamperes. Ray earthing uses a low-resistance path created by extending radial conductors outward from the main grounding station. This geometry reduces the overall ground resistance (Rg) by increasing the surface area contact with the soil and allowing the fault current to dissipate over a larger volume of earth.
High-voltage systems require extremely low earth resistance to ensure safety and equipment protection.
Ray earthing provides better current dissipation compared to single pipe or rod electrodes.
Used extensively in substations, switchyards, and power generation plants.
The radial design minimizes the step and touch potential in the vicinity of the fault.
Superior dissipation of large fault currents
Provides a very low impedance path to ground
Effective in various soil types
Requires significant land area for installation
Higher installation and excavation costs
HV and EHV Substations
Large Power Generating Stations
High-voltage transmission infrastructure
Pipe earthing (Option B) is standard for domestic and low-voltage industrial applications.
Strip earthing (Option D) is often used in rocky soil where deep excavation is difficult.
Ray earthing is often integrated with the Main Earth Mat of a grid substation.
A is correct — Ray earthing is specifically designed for high-voltage systems to effectively dissipate massive fault currents through a radial network of conductors.
Always remember: Pipe/Rod for Low Voltage, Strip for rocky terrain, and Ray/Grid for High Voltage systems.