Deployable Fiber Optic Systems for Harsh Industrial Environments
As the utilization of fiber optics in the industrial sector has increased, so have the number of “deployable” systems used in applications ranging from oil and gas exploration to drilling and distribution to mining. Deployable systems, as opposed to fixed installations, are designed to be quickly installed, retracted, and then relocated in the field and even deep underground in some of the most inhospitable environments on earth.
Given the environments in which they reside, industrial-grade fiber optic systems are typically commercialized versions of field-tested, proven military-grade products. As such, the component parts of the system are designed to withstand everything from dust and debris to chemical exposure, temperature extremes, UV, radiation, electrical power transients, interference, fire, moisture, humidity, water, crush, tension, flexing, impact, and vibration.
When designing a deployable fiber optic system, designers need to look at the system in its entirety. Unlike fixed applications, a deployable system is designed from beginning to end (plug-and-play) and delivered to the customer as a complete solution. The primary elements of a deployable system include hardened cable jacketing; “genderless” connectors for quick deployment without regard for male or female ends; hybrid systems that include copper along with fiber to deliver data communications and power; and reel systems that speed deployment and retraction while protecting the fiber while not in use or during transit.
For purposes of deployment, Optical Cable Corporation (OCC) typically recommends its tight-bound, tight-buffered distribution-style cabling, which is ideal because of its small diameter and lightweight construction.
Distribution-style cables have a tight-bound outer jacket, which is pressure-extruded directly over the cable’s core. This combination of a helically stranded core and a pressure-extruded outer jacket provides an overall cable construction that offers better crush and impact protection and increased tensile strength. This also reduces outer jacket buckling during deployment. Escalating degrees of cable protection are available as needed to meet the specific needs of an application.
Various jacket materials are available as well, including PVC or polyurethanes, which are specifically tailored to meet the mechanical and environmental needs of the application. Options within each jacket material include coefficient of friction, cold temperature flexibility, and temperature range, to name a few. Water-tolerant options take advantage of the qualities of tight-buffered cable and super-absorbent polymer aramid yarn, and fiberglass or metal braided jackets not only provide excellent abrasion resistance, but also deliver increased rodent protection. (In deployable applications, exposed cable is often an intriguing temptation for animals, which can, and often do, chew on it.)
Hybrid Cables and Connectors
For applications that can benefit from fiber optics and copper, hybrid connector-cables offer both within the same cabling sheath. A distinct advantage of hybrid cable-connector solutions is that the customer can bundle both the high performance of fiber with the copper power or control signals in one cable. This reduces the number of cables that must be designed, purchased, and deployed into a system. It also offers distinct savings in labor and cable structure costs for the customer.
“Genderless” connectors have both male and female elements, and perhaps are more appropriately described as dual-gender. They are designed for quick deployment, allowing the user to unreel fiber cable without regard for male or female ends. Companies such as OCC have further simplified the genderless design with user-friendly mating interfaces capable of “blind mate” and/or applications that require thousands of mating cycles. In addition, the connector system is designed to resist extreme harsh mechanical and environmental conditions, including high vibration, mechanical and thermal shock, and fluid immersion.
Another benefit of genderless connectors is that multiple identical cable assemblies can be daisy-chained (sequenced) together to extend the distance of a deployable system while maintaining polarity. Polarity can be an issue when connecting an odd number of traditional male to female gender connectors. In such cases, an additional connector is required to correct polarity. However, such connectors are known for high loss and add additional components for the customer. Therefore, genderless connectors are uniquely advantaged over traditional interconnection systems. Distances of several kilometers are possible, limited only by system link budget (dBm). This type of genderless connector provides extreme flexibility in the case of redeployment, where the length of the cable assemblies required for the next application may not be fixed, or even known.
The key characteristics of a reel system in deployable fiber optic applications are that it is lightweight and stackable for storage and transit. To meet these requirements, companies provide lightweight alternatives to traditional metal reels. Constructed of durable, yet lightweight, impact-absorbing polymers, these modular advanced reel systems are designed specifically for the demanding needs of harsh-environment fiber optic installations.
Reels can be used with simple deployable axle or flange-supported deployment and acquisition systems. These types of systems include A-frames, cable acquisition cradles, transit case systems, tripods, bumper mounts, backpacks, backpacks with fiber optic slip rings, and cartridge systems.
The cartridge system, which comes with casters, is an ideal choice in many deployable applications. Using a cartridge system, a single person can handle multiple spools at once and can quickly deploy fiber and rewind on the reel without assistance.
To simplify shipping and transit, cartridge systems, transit cases, and reels are designed with interlocking stacking features. Reel systems also provide a measure of protection for unspooled cabling or when the cabling is retracted.
In harsh environments, when a customer can put fiber optic assemblies in a controlled environment storage system like a reel, any potential damage to the cable or the connectors is minimized. This reduces the need to refurbish components regularly, because the system is better protected during its deployment.
Wireless Access/Data Communications
Although deployable fiber optic systems are largely “wired,” hybrid cabling (the combination of fiber optic and copper/electrical within the same cable sheath) also allows for installation of wireless access points anywhere, even underground. This is ideal when access points are constantly changing.
Unlike traditional wireless networking devices that require 110 VAC power for each device, with a hybrid system, power can be supplied in the same cable that also carries voice and data.
As a result, any 802.11-certified devices are able to communicate through the network, including personal devices such as PDAs, laptops, VOIP devices, and cell phones.
This provides personnel, even deep within mines, with the means to communicate with each other and even make calls outside the system. In addition, sensor-based data, such as temperature, humidity, airflow, and gas, can also be collected and delivered wirelessly for use by the entire network.
Increasing Conversion to Fiber Optics
Many industrial companies that converting to fiber optics as the costs for components continue to drop, making fiber a better solution than copper in most applications. Even die-hard copper devotees are moving to fiber — and when they do, they rarely look back.
By Rick Hobbs, Director of Business Development at Optical Cable Corporation