OPGW stands for Optical Ground Wire. The characteristic of the Optical Fibre is that there is no effect of high voltage induction on the data being transmitted through the Fibres. Hence this characteristic of the Fibre is exploited to transmit the data along the high power transmission lines.
High Voltage Power Transmission (400/220 KV etc.) runs along the
countryside over very long distances. The huge towers used for this purpose
usually have 6 power-carrying conductors and one thin wire running on top of the
towers, called the Ground Wire. Its function is to protect the power conductors
against lightning strikes. During thunderstorms lightning hits are common on
these towers and conductors, as they are the highest conducting structures
present in the area. The Ground Wire being the
highest conductor on the tower, grounded properly, attracts the lightning way
from the power conductors and towers onto itself and safely discharges the
current to the ground.
An OPGW Cable
is a special type of Ground Wire in which Optical Fibres are also embedded along
with ground wire during manufacturing process to provide a high capacity data channel for communication
purposes. Thus it helps in providing dual functions of Earth Wire and Optical Fibres which can be used for high bandwidth data transmission.
However it may be noted that OPGW installation increases the weight and tension load on the towers so tower reliability, life span may get reduced, if proper engineering study is not done. Some towers may need to be replaced, refitted, reinforced etc during the process.
Altogether OPGW is an additional advantage to provide high bandwidth along with the installation works of power cables. The additional expenses are very less as most of the expenses are covered under installation works of power lines. Hence it is a boon to the telecom and IT sector for cheap and reliable media for transmission purposes. The power companies on their part get extra revenue for a small investment.