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By which of the following method bulk electric power for a long distance may be transmitted from one location to another location?
UnderGround System
Overhead system
UnderGround System & Overhead system
None of the above
Overhead system
Overhead transmission systems are the standard for long-distance power bulk transfer due to their cost-effectiveness and ease of maintenance. They utilize bare conductors suspended on towers or poles, using air as the primary insulating medium.
Overhead transmission systems are the standard for long-distance power bulk transfer due to their cost-effectiveness and ease of maintenance. They utilize bare conductors suspended on towers or poles, using air as the primary insulating medium.
PlossтАЛ=3I2R тАФ Power loss in three-phase line
VdropтАЛтЙИIRcos╧Х+IXsin╧Х тАФ Approximate voltage drop
The system transmits bulk power by stepping up the voltage using transformers to reduce I2R losses and voltage drop. The overhead conductors are supported by insulators on towers, where air serves as the dielectric to prevent flashover, making it more economical for long distances compared to underground cables which require expensive XLPE or oil-impregnated paper insulation.
Overhead lines use air as a natural, free insulator.
Easier to locate and repair faults in overhead systems.
Corona effect is a significant consideration in high-voltage AC overhead lines.
Underground cables have high charging current due to high capacitance (C).
Low installation and maintenance costs.
Easy to detect and repair faults.
Current carrying capacity is higher due to better heat dissipation.
Expansion is easier compared to underground conduits.
Susceptible to lightning and weather-related outages.
Higher chance of public accidents.
Requires significant Right-of-Way (ROW) clearance.
Radio and television interference (Corona).
High Voltage (HV) and Extra High Voltage (EHV) bulk power transmission.
Rural electrification and sub-transmission networks.
| Feature | Underground | Overhead |
|---|---|---|
Insulation | Solid/Oil/Gas | Air |
Cost | Very High | Low |
Underground systems are generally used only in densely populated urban areas or river crossings due to extreme costs.
Option A is incorrect because underground cabling is prohibitively expensive for long-distance bulk power transmission.
B is correct тАФ Overhead systems are the most economically viable and standard method for long-distance bulk power transmission.
Always remember that for transmission voltage V>66kV, overhead lines become significantly more economical than underground cables, which face limits due to dielectric stress.