The transmission of electrical power can be done either through the usage of overhead or underground transmission lines. However, both lines have pros and cons when it comes to their common use and place.
Which transmission line is better: underground transmission line or overhead transmission system?
Yabtir Ahor
The overhead transmission lines are the pylons supported bared conductors. Pole transmission lines are mounted at certain distances to hold these conductors in the air. Underground lines are the insulated cables that are buried beneath the earth. The underground cables, vaults and trenches are installed.
Location of fault:
The overhead lines are visible; it is easy to detect the location of the fault and to repair it. Yet that becomes more difficult in case of underground line, so it may require some time to find and repair it.
Effect of lightning:
Overhead line is more prone to thunders and natural lighting, whereas the underground line is not affected by lighting as they are buried deep under the earth.
Life span:
In contrast to underground lines, the overhead lines provide a longer operating period. The life span of underground lines is 30 to 35 years about half of the overhead lines, whereas overhead lines can work for 70 years.
Environmental impacts:
The overhead and underground lines differ quite fundamentally when it comes to their respective impact on the environment. The underground lines have significant environmental and health safety advantages owing to reduced noise and better control of vegetation. Moreover, they provide minimal loss of transmission, less disruption and incidents such as electrocutions for wildlife. On the other hand, humans, animal intervention, natural disasters such as heavy wind storms and floods as well as larger plants can pull down the overhead lines. These conditions have a less visual impact on underground lines.
Costs:
The cost of underground transmission lines is 5 to 10 times higher than the overhead line. Insulated cables, underground surveying and diggings, splicing vaults to protect the line from dig-in adds to higher costs.
Applications:
Overhead transmission lines are used for the distribution system in the long-distance transmission system and rural areas due to the low cost of these systems. The overhead lines are more practical in open areas. In contrast, the underground lines are used in short distances, particularly in heavily populated areas because of the high cost. Secondly, where there is a big concern of space to the overhead lines.