Electric power transmission occurs in two main ways: through underground cables and overhead lines. Both methods are used to supply energy over long distances from power generation sources to consumers. Each method has its advantages, disadvantages, and specific use cases, depending on the area, climate conditions, and other technical requirements.
Electric Power Transmission via Overhead Lines:
Power is transmitted via overhead lines using conductors suspended on high-voltage poles. This method is widely used due to its simplicity, relatively low cost, and ease of maintenance.
Main Components of Overhead Lines:
Conductors (Wires): Typically bare aluminum or copper wires are used, as these materials are excellent electrical conductors, ensuring minimal resistance to the electric flow.
Aluminum Conductors: Aluminum is commonly used due to its light weight and good conductivity, though copper may still be used in high-quality lines.
Bare Conductors: Since overhead lines are exposed, they do not need insulation – the surrounding air acts as a natural insulator.
Poles: Poles of various heights are used to elevate the lines above ground, ensuring they are out of reach from people or vehicles. They may be made from wood, steel, or concrete.
Insulators: Insulators protect the wires from poles and environmental effects, ensuring that electricity is not lost due to ground contact.
Advantages of Overhead Lines:
Cost: Building overhead lines is cheaper than underground cables, especially over long distances.
Maintenance: Overhead lines are easily accessible for maintenance and repair. Faults can be quickly identified and resolved.
Efficiency: Overhead transmission is efficient over long distances, especially at high voltage.
Disadvantages of Overhead Lines:
Environmental Impact: Overhead lines are vulnerable to natural elements like storms, snow, and strong winds, which can damage the lines or cause accidents.
Aesthetics: Overhead lines can disrupt the landscape visually, so underground transmission is often preferred in urban areas or scenic locations.
Electromagnetic Radiation: Overhead lines create electromagnetic fields, which may impact health or interfere with electronic devices.
Electric Power Transmission via Underground Cables:
Electric transmission via underground cables is common in urban areas or where overhead lines would be impractical or unsuitable.
Main Components of Underground Cables:
Cables: Underground cables are insulated with special materials, often cross-linked polyethylene (XLPE) or PVC, to protect them from moisture, heat, corrosion, and mechanical damage.
Copper or Aluminum Conductors: As in overhead lines, copper or aluminum is used due to their conductivity.
Insulation: Cables are carefully insulated with several layers to prevent moisture, mechanical damage, and electricity leakage.
Protective Sheaths: Armored cables with metal layers may be used in some areas to protect against mechanical damage, especially when deeply buried.
Advantages of Underground Cables:
Protection from Environmental Factors: Underground cables are safe from storms, wind, ice, and other natural conditions, resulting in fewer faults.
Aesthetics: Underground lines are hidden and do not disrupt landscapes or city views.
Safety: Cables are better protected from human or animal contact, reducing accident risks.
Disadvantages of Underground Cables:
Cost: Installing underground cables is more expensive, requiring extensive excavation and specialized insulation.
Maintenance and Repair: Detecting and fixing faults is more complex and costly as it requires excavation to reach the damaged cable.
Cooling: Underground cables lack natural air cooling, which may cause overheating, especially in high-power systems.
Comparison of Overhead Lines and Underground Cables:
Usage Cases:
Overhead lines are the preferred solution in rural and forest areas or where power transmission spans large distances across uninhabited areas.
Underground cables are common in city centers, industrial zones, or sensitive environmental areas where overhead lines would be unsuitable due to aesthetics or space constraints.
Both overhead lines and underground cables are crucial for power transmission, and the choice between them depends on specific location requirements and technical needs.
