UNDERGROUND AND OVERHEAD CABLE WIRING SYSTEM: WHICH IS MORE EFFICIENT?

By: Jessie James B. Prado

Electricity is transmitted via cables from the generating plant to the user. Two major conductor systems are developed called transmission system and distribution system. Both transmission and distribution systems are further divided into two types namely, overhead system and underground system. Electricity has traditionally been distributed to consumers in the overhead transmission [1] on and distribution system using wires that are attached to poles that are located far above the ground. The overhead system's transformers and other components are installed on poles or other supporting structures. While underground cables installed and buried below the ground for the transportation of electrical power. Instead of being carried overhead as aerial cables several meters aboveground, these wires that distribute electrical power and communications are buried underground.

Pros and Cons

There are two typical ways to install utility power lines: overhead and underground. Both of these choices offer advantages and disadvantages. Overhead transmission lines are widely used because they are easy to install and inexpensive to install. In comparison to underground wiring, installing above electricity lines is comparatively simple. It is also easier to add extra connections. However, it has several drawbacks including low reliability and power lines are more susceptible to signal interference than underground power lines. Also, voltage drops are more likely to affect them. The signals of communication cables are disrupted by above power wires. Since they are buried beneath the earth's surface, underground power lines are not susceptible to any of those issues because of their positioning. Therefore, the signal quality in underground power cables is greater. Although underground cables perform best in such circumstances, their use is expanding due to their numerous clear benefits, including lower transmission losses, fewer maintenance costs, and reduced sensitivity to the effects of extreme weather. Underground transmission lines are typically used at significant locations or popular tourist destinations. Cleaner cities have underground electricity lines. One major argument in favor of underground power lines in cities is the aesthetic consideration. Due to its higher reliability and superior scenic attractiveness compared to overhead transmission lines, this form of installation is expanding quickly. As a result, there are more sites where underground cable and overhead line can be connected. Considering that individuals cannot come in contact with underground electrical lines, they are far safer for the general population. Natural catastrophes do not affect underground power lines nearly as much as they do overhead ones, although lines are still easily damaged by adverse weather conditions like lightning, thunderstorms, wind storms, and so forth. The hazards of death and injury to the general public are significantly higher in areas with overhead power lines. The primary argument in favor of underground electricity lines, among environmental concerns, is this. Since they make less noise than overhead power lines and are less likely to collide with trees, animals, and other plants—including those that are endangered—underground power cables are seen to be better for the environment. In addition, underground electricity cables are secure during natural calamities. However, it has certain drawbacks, including difficulty in locating the source of the fault, high cost, lower current carrying capacity, and lower voltage rating, which is normally just 66 kV. Also, the parameters of each type of transmission line vary. This could harm the power system and affect the capacity of the protection system to locate and identify the issue.

Cost

“Why can't overhead electricity lines be buried?” is a common question that arises whenever a significant weather-related tragedy takes place or land is being developed. Since underground cables require better insulation that has resistant soil, weather, and chemicals, they are more than ten times more expensive to produce. These costs include the underground cable, which is typically more expensive than overhead conductors, the materials needed to bury the cable in the earth (such as installing the cables in concrete ducts), and the continuous excavation (or horizontal drilling) required for underground transmission as opposed to the use of poles, tower structures, and foundations for overhead transmission. Because underground electricity cables are more difficult to replace and upgrade, their cost is increased. Because underground power lines are completely insulated, overhead power lines are only insulated at the contact tower, which contributes to their lower cost. Yet, compared to underground cables, which have comparatively low maintenance costs, overhead wires have higher maintenance costs. The primary reason overhead power wires are still used frequently is cost. Due to the high investment and maintenance costs as well as the significant repair costs in the event of an outage, underground power line installation is still only a restricted option.

Conclusion

Many advocates for the development of underground power lines for reasons of safety and the [2] environment, overhead power lines continue to be widely used due to its affordability, simplicity of maintenance, and capacity to transport higher voltages. Although installing and building underground cables costs [3] More money, they are more convenient and less prone to break. The particular situation determines which cable should be used. Due to their price and capacity to transport more power than underground cables, overhead cables are used extensively.

References

[1]	J. &. N. A. Klomjit, "Fault classification on the hybrid transmission line system between overhead line and underground cable.," 2017.
[2]	M. R. K. S. C. &. P. A. S. Hans, "Identification of underground cable fault location and development.," 2017.
[3]	P. R. M. R. R. V. C. P. V. A. J. D. &. R. B. Ocłoń, " Multiobjective optimization of underground power cable systems.," 2020.