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OPGW  (OPTICAL FIBRE OVER GROUND WIRE)


TClL has mult million USD OPGW Projects in Algeria for replacement of ground wire of the HT transmission system with OPGW under live line conditions on existing 40 nos 220 KV power transmission lines. These 220KV power transmission line cover a total distance of about 3000 Kms and pass through terrorist infested areas in mountains, forests and deserts of all the 42 wilayas (districts) spanning Algeria.

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.

  1. OPGW provides a relatively low cost solution to provide Communication and Data backbone trunks.

  2. As the Power Transmission Company has right of way for its towers it need not acquire land to lay down the fibre optic cable.

  3. No digging, trenching, filling etc. is required as the cable is laid high in the air and not under ground. This is especially advantageous in hilly, marshy, rocky terrain.

  4. The cable is not damaged by human or animal actions as it is out of reach of both of them.

  5. The cable is well protected by a bundle of strong steel or aluminum conductors.

  6. Wherever the towers have Ground wires the new cable can be laid under live  conditions i.e. power need not be switched off. Only in the absence of Original Ground Wire, power needs to be switched off to lay the conductors.

  7.  OPGW provides Power Companies an opportunity to use their towers for other purpose than power transmission. They for a small investment can provide Extremely High Capacity Links to the Telecom sector.

  8. As Power Companies have sub-stations all along the route equipment installation space, power supply, security is also available for the communication equipment.

  9. Same optical equipment can be used as in case of underground optical fibre cables.

  10. The data transmission capacity can be increased as and when needed by just upgrading the optical fibre equipment. The fibre once installed remains the same for its lifetime of around 40 years.

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.