Overhead transmission lines have once been an important form of transmitting power but no longer! Today, it is the underground cables which have gained greater popularity as a source of power transmission. And that is because of the several advantages offered by them.

Shortcomings of Overhead Transmission

Overhead transmission lines have to face the vagaries of weather. Tree branches borne by winds or extremely windy conditions cause damage and come in the way of their effective functioning. Natural disasters also act as a hindrance at the power companies’ end while transmitting power to the end consumers. Most of the times, power flow limits occur because of a drop in voltage or over-electrical phase shift or quality issues in substation equipment or due to some thermal shortcomings in the power lines. Moreover, lack of insulation of these power lines can cause serious injury to people. The area that has to be always kept clear around these overhead transmission lines for the purposes of repair and maintenance as well as safety purposes is about 20-200 metres wide. This is a pretty large area which cannot be used for any other purpose.

Pros and Cons for Underground Transmission Lines

Firstly, the strip around the underground transmission lines that have to be kept free is limited to 1-10 metres only. Lesser area is occupied for this reason. Underground transmission lines have low impedance and this feature ensures that there is less transmission loss. The amount of power load that can be borne by these lines is greater than that borne by the overhead transmission lines. Zero electric field and a lesser magnetic field is emitted by these lines in comparison to that of the overhead line. Effects of bad or adverse weather are not experienced by these due to the insulation technology in use.

However, there are a couple of shortcomings too. One of them is the higher cost of installation and maintenance and therefore underground transmission lines are prevalent in areas with dense populations. Moreover, if there are irregularities in their working then time required to sort out the problems is much more than that required for an overhead transmission line.

Cutting-Edge Advantage

Sophisticated insulation technology in use today however, gives a cutting edge advantage to the underground transmission lines. Heat shrink protection assumes great importance here. Heat shrink tubes used in all electrical insulations today offer protection from chemicals, dust and other foreign bodies besides providing relief from mechanical strain. Insulators that give total resistance to salty atmospheric conditions or polluted environment are being used to stabilize the electric flow. A heat shrink boot which is coated with adhesive material safeguards the cable from mechanical abuse and corrosion as it forms a watertight seal around it. The heat shrink boots fulfil the requirements of almost all electrical interconnect designs and helps to close the bridge between the connectors and sealed cable assemblies. PVC caps of the heat shrink variety are also useful here.

Underground cabling is definitely a better alternative because of the several advantages offered by it as against the overhead transmission lines.