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ElectricalPower System
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Which type of earthing is done in a high voltage system or equipment?

A

Ray Earthing

B

Pipe earthing

C

Coil earthing

D

Strip

Correct Answer

тЪЩя╕П TE тАв Technical Concept & PrincipleElectricalPower System
Option A

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.

тЪЩя╕ПTETechnical SolutionConcept & Principle
ЁЯТб Explanation

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.

ЁЯФв Key Formulas

RgтЙИ╧Б2╧АLlnтБб(4Ld)R_g \approx \frac{\rho}{2\pi L} \ln(\frac{4L}{d})RgтАЛтЙИ2╧АL╧БтАЛln(d4LтАЛ) тАФ Simplified resistance estimation for an earth electrode where ╧Б\rho╧Б is soil resistivity, LLL is length, and ddd is diameter.

тЪЩя╕П Working Principle

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 (RgR_gRgтАЛ) by increasing the surface area contact with the soil and allowing the fault current to dissipate over a larger volume of earth.

ЁЯУМ Key Points
  • тЦ╕

    High-voltage systems require extremely low earth resistance to ensure safety and equipment protection.

  • тЦ╕

    Ray earthing provides better current dissipation compared to single pipe or rod electrodes.

  • тЦ╕

    Used extensively in substations, switchyards, and power generation plants.

  • тЦ╕

    The radial design minimizes the step and touch potential in the vicinity of the fault.

тЬЕ Advantages
  • тЦ╕

    Superior dissipation of large fault currents

  • тЦ╕

    Provides a very low impedance path to ground

  • тЦ╕

    Effective in various soil types

тЭМ Disadvantages / Limitations
  • тЦ╕

    Requires significant land area for installation

  • тЦ╕

    Higher installation and excavation costs

ЁЯЫая╕П Applications / Uses
  • тЦ╕

    HV and EHV Substations

  • тЦ╕

    Large Power Generating Stations

  • тЦ╕

    High-voltage transmission infrastructure

ЁЯУД Additional Information
  • тЦ╕

    Pipe earthing (Option B) is standard for domestic and low-voltage industrial applications.

  • тЦ╕

    Strip earthing (Option D) is often used in rocky soil where deep excavation is difficult.

  • тЦ╕

    Ray earthing is often integrated with the Main Earth Mat of a grid substation.

ЁЯУК Diagram / Illustration
Ray Earthing PrincipleRadial Conductors for HV Fault Dissipation
тЬЕ

A is correct тАФ Ray earthing is specifically designed for high-voltage systems to effectively dissipate massive fault currents through a radial network of conductors.

Core Concepts Used
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Grounding Resistance Step Potential Fault Current Dissipation
ЁЯТб EXAM TIP

Always remember: Pipe/Rod for Low Voltage, Strip for rocky terrain, and Ray/Grid for High Voltage systems.

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