AFL HexaCore Optical Ground Wire (OPGW) cable utilizes fiber-bearing stainless steel tubes stranded alongside aluminum clad steel and/or aluminum alloy wires to create a multi-layer cable design suitable for a variety of environmental and geographical conditions. HexaCore OPGW was developed in response to the demand for higher fiber counts, specifically those greater than 96. For traditional OPGW designs, as the fiber count increased, so too did the cable diameter and weight. However, the advent of placing optical fibers into small diameter stainless steel tubes has allowed for smaller cable sizes with higher fiber counts, thereby furthering the expansion of OPGW into even more applications.
Optical Ground Wire (OPGW) is a dual functioning cable. 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.
AFL has been manufacturing Optical Ground Wire (OPGW) since 1985 and has supplied hundreds of thousands of kilometers of cable since our inception. HexaCore OPGW was introduced by AFL in the mid-to-late 1990’s in response to the tremendous push to build higher fiber count backhaul networks. With fiber counts of 144, 216 and even 432 becoming the norm, AFL recognized the need to condense the fibers into smaller, more compact bundles. The use of stainless steel tubes to house as many as 72 fibers in a 3.8mm diameter became a staple of AFL’s product portfolio, allowing AFL to provide the much-needed higher fiber counts without impacting the cable dimensions. Multiple stainless steel tubes, depending on the fiber count, are stranded with steel and/or alloy wires to make an OPGW that resembles more traditional conductor cable. The fibers are grouped in bundles of 12 with color-coded threads denoting the different bundles. The standard color sequence (Blue, Orange, Green, Brown, etc.) is used for the individual fibers as well as for the threads identifying the bundles.
The name “HexaCore” is a blend of the Greek word for six (“hex”) and AFL’s family name for OPGW cables which all end in “Core”. There are traditionally six positions in the first layer of this cable design, thus the tie back to “hex”. However, note that AFL also uses terms for other variants of its stranded stainless steel tube family design including PentaCore, QuadCore, and TriCore, which, as you might guess, indicate five, four and three positions respectively in the first layer of the cable. There is traditionally one inner layer (with the stainless steel tubes and wires) and one outer layer of steel and/or alloy wires. But there are occasions where there might be two or even three outer layers of wire, depending on the requirements of the application for strength and fault current capacity.