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By which of the following method electric power may be transmitted from one location to another location?
UnderGround System
Overhead system
Both 1 and 2
None of the above
Both 1 and 2
Electric power transmission is achieved by either overhead lines using conductors supported by towers or poles, or underground systems using insulated cables buried in trenches. Both methods are industry-standard depending on voltage levels, environmental constraints, and economic factors.
Electric power transmission is achieved by either overhead lines using conductors supported by towers or poles, or underground systems using insulated cables buried in trenches. Both methods are industry-standard depending on voltage levels, environmental constraints, and economic factors.
R=╧БAlтАЛ тАФ Resistance depends on length and cross-section, crucial for transmission loss calculation
P=3тАЛVLтАЛILтАЛcos(╧Х) тАФ Power equation for three-phase transmission
Overhead systems utilize air as an insulating medium, making them cost-effective for long-distance high-voltage transmission. Underground systems utilize solid or liquid-impregnated dielectric materials within cables, which are safer for congested urban areas despite higher installation costs.
Overhead systems are standard for extra-high voltage (EHV) and ultra-high voltage (UHV) transmission due to ease of maintenance.
Underground systems are restricted by high capacitive charging currents and thermal dissipation limits.
Transmission voltage level inversely affects the line current for a constant power, reducing I2R losses.
Overhead: Lower cost, easier fault detection, higher current-carrying capacity.
Underground: Immunity to atmospheric disturbances (lightning, storms), aesthetic benefits in urban areas.
Overhead: Prone to environmental faults, aesthetic issues, requires wide right-of-way.
Underground: Extremely high installation cost, difficulty in locating faults, restricted heat dissipation.
Overhead: Rural electrification, long-distance inter-state power corridors.
Underground: City centers, dense metropolitan areas, river/sea crossings.
| Feature | Overhead | Underground |
|---|---|---|
Insulation | Air | Solid Dielectric/Oil |
Cost | Low | High |
Underground cables are categorized by voltage rating (LV, MV, HV, EHV) and type of insulation such as XLPE or PILC.
Transmission of power at higher voltages reduces the I2R line losses and improves voltage regulation.
C is correct тАФ Electric power can be transmitted via both overhead transmission lines and underground cable systems depending on the specific requirements of the utility network.
Always remember that for underground cables, the high shunt capacitance (C) causes significant charging current, which is a limiting factor for long-distance underground transmission.