The development of smart energy management systems is the need of the hour and is aimed at alleviating the burgeoning demands from today’s power infrastructures. Optical Fiber Composite Ground Wire (OPGW) is a revolutionary solution that enables synergies between efficient power distribution grids and high-speed optical fiber-based SCADA networks, giving power utility companies the unique capabilities of a telecom carrier or service provider.

The functional aspects

OPGW replaces a conventional ground wire (or earth wire) to protect the transmission system from lightning strikes and serves as a conductive medium for carrying fault currents to ground. It also acts as a medium for real-time monitoring and security of the transmission system over which it is installed – doubling up for SCADA controls and network.

Such cable combines the functions of grounding and communications. An OPGW cable contains a tubular structure with one or more optical fibers in it, surrounded by layers of steel and aluminum wire.

The OPGW cable is run between the tops of high-voltage electricity pylons. The conductive part of the cable serves to bond adjacent towers to earth ground, and shields the high-voltage conductors from lightning strikes. The optical fibers within the cable can be used for high-speed transmission of data, either for the electrical utility’s own purposes of protection and control of the transmission line, for the utility’s own voice and data communication, or may be leased or sold to third parties to serve as a high-speed fiber interconnection between cities.

The optical fiber itself is an insulator and protects against power transmission line and lightning induction, external noise and cross talk. Typically OPGW cables contain single-mode optical fibers with low transmission loss, allowing long distance transmission at high speeds.

Design considerations for OPGW cables

OPGW cables are required to withstand the effects from installation and long-term in-service exposure to mechanical, electrical and environmental loads without allowing any significant degradation in its performance. OPGW cables would need to fulfill basic performance criteria to enable selection of an appropriate design.

(a) Electrical performance:

• Fault current performance to overcome the line-to-tower short circuits or system unbalances.
• Lighting performance so that lighting arcs do not impair the long-term functionality of the cable.

(b) Mechanical performance

• Sag and tension
• Vibration
• Galloping and Sheave

(c) Environmental performance

• Range of temperatures & wind zones
• Corrosion levels at the installation sites including the pollution level (1-4)
• Salinity levels

Attraise’s OPGW hardware