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Examoogle • User • info@examoogle.com • EE-2024-8821
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What type of earthing is done in a power station?
Plate earthing
Pipe earthing
Coil earthing
All of above
Pipe earthing
Quick Summary: Pipe earthing is the preferred method for power stations and large electrical installations because it provides a very low resistance path to the ground and can handle high fault currents. It involves burying a galvanized steel pipe vertically into the earth to ensure deep penetration where soil moisture remains consistent throughout the year.
Pipe earthing is the preferred method for power stations and large electrical installations because it provides a very low resistance path to the ground and can handle high fault currents. It involves burying a galvanized steel pipe vertically into the earth to ensure deep penetration where soil moisture remains consistent throughout the year.
R=2πLρln(d4L) — Simplified formula for resistance of a pipe electrode where R is resistance, ρ is soil resistivity, L is length, and d is diameter.
The pipe earthing system utilizes a perforated galvanized steel pipe placed vertically into the ground. A salt and charcoal mixture is often added around the pipe to reduce soil resistivity. This arrangement allows the dissipation of fault currents deep into the moist, conductive layers of the earth, ensuring the station's grounding grid remains at a safe potential.
Pipe earthing is more efficient than plate earthing in high-resistivity soil.
The length and diameter of the pipe are chosen based on the fault current rating of the substation.
Periodic maintenance involves pouring water into the funnel to maintain soil moisture levels.
It is the most common and standardized method for power station grounding according to IS standards.
Can be installed at deeper soil levels to achieve lower resistance.
Economical and easier to install compared to plate electrodes in limited space.
High current carrying capacity.
Requires periodic water treatment to maintain moisture.
Susceptible to corrosion over long periods.
Power generating stations
Transmission substations
Large industrial transformer installations
| Feature | Plate Earthing | Pipe Earthing |
|---|---|---|
Depth | Shallow | Deep |
Moisture Consistency | Less consistent | Highly consistent |
Standard pipe diameter for major substations typically ranges from 38mm to 50mm.
Plate earthing is usually reserved for smaller installations or areas where soil resistivity is low at shallow depths.
Coil earthing is rarely used in power stations due to its inability to handle high fault energy.
B is correct — Pipe earthing is the standard method used in power stations for its ability to provide a deep, reliable, and low-resistance path to the earth.
Always remember that earthing requirements depend on Rearth≤Ifault50, where Rearth is the resistance of the earthing system.