OPGW is primarily used by the electric utility industry, placed in the secure topmost position of the transmission line where it “shields” the all-important conductors from lightning while providing a telecommunications path for internal as well as third party communications. Optical Ground Wire is a dual functioning cable, meaning it serves two purposes. It is designed to replace traditional static / shield / earth wires on overhead transmission lines with the added benefit of containing optical fibers which can be used for telecommunications purposes. OPGW must be capable of withstanding the mechanical stresses applied to overhead cables by environmental factors such as wind and ice. OPGW must also be capable of handling electrical faults on the transmission line by providing a path to ground without damaging the sensitive optical fibers inside the cable.
OPGW cable has two constructions:
Central loose tube type—The fibers are placed loosely in a sealed and water resistant central, aluminum tube filled with water blocking gel. This tube provides protection to the fiber during installation and operation under severe environmental conditions. The stainless steel tube may also be aluminum-clad steel depending on the engineering requirements. The stainless optical tube is located at the center of the cable protected by single or multiple layers of aluminum clad steel, aluminum alloy wires, or steel wires. The metallic wires provide mechanical strength to withstand severe installation and operating conditions, while achieving conductivity to control temperature rise during short circuit conditions.
Each optical fiber is clearly distinguishable utilizing a fiber identification system consisting of coloring and the number of ring marks on it. This compact design features high mechanical strength and fault current rating within a smaller diameter. The smaller diameter also results in excellent sag tension performance.
ASTM B416-98, AS1222, IEC61089
|Number /diameter(mm) of stainless steel tube||1/3.5||2/2.4||2/2.6||2/2.8||1/3.0|
|Number /diameter of AL wire(mm)||0/3.5||12/2.4||12/2.6||12/2.8||12/3.0|
|Number /diameter of ACS wire(mm)||6/3.5||5/2.4||5/2.6||5/2.8||6/3.0|
|Diameter of Cable (mm)||10.5||12.0||13.0||14.0||15.0|
|Cable weight (kg/km)||415||320||374||432||527|
|DC resistance(200C W/km)||1.36||0.524||0.448||0.386||0.327|
|Modulus of elasticity(Gpa)||162.0||96.1||95.9||95.6||97.8|
|coefficient of Linear thermal expansion(1/℃×10-6)||12.6||17.8||17.8||17.8||17.2|
|Short circuit capacity (kA²s)||24.0||57.3||78.9||105.8||150.4|
|Max. operation temperature (℃)||200||200||200||200||200|
|Max. fiber count||48||32||48||52||30|