The harsh-environment initiative is one of several in progress within the TIA TR-42 engineering commitee.
Patrick McLaughlin
Professionals who install, maintain, and use structured cabling systems in industrial environments will someday have a standard to call their own, reported Paul Kish, chair of the Telecommunications Industry Association's (TIA-Arlington, VA) TR-42 Engineering Committee. Kish explained the efforts being made toward an Industrial Ethernet cabling standard when he addressed the attendees of BICSI's (Tampa, FL) Fall Conference in August. He also took the opportunity to update attendees on other TIA initiatives-some of which Cabling Installation & Maintenance regularly updates as well.
Kish began his presentation with a quick overview of technology drivers that are pushing data-transmission speeds faster. He then tied these increasing data rates to the need for more robust infrastructures on which the data travels. And standards, of course, set minimum performance requirements for those cabling infrastructures.
Several major trends contribute to growth in corporate local-area-network (LAN) bandwidth, including:
- Internet traffic doubling every three months;
- Data traffic increasing 35% annually;
- Rapid growth in the amount of outbound traffic;
- A mixture of real-time and file-transfer data; and
- A prevalence of switched LANs, as opposed to shared LANs.
Internet file sizes will grow rapidly, Kish explained, driven predominantly by increased access bandwidth. As more and more users move from analog modems to digital subscriber line (DSL), cable modems, and other high-speed access technologies, Internet-access bandwidth will require 20- to 200-fold increases.
Industrial cabling
The TIA/EIA-568A standard, which is probably the most commonly referenced cabling standard in conversation, print publications, and job specifications, is officially titled the Commercial Building Telecommunications Cabling Standard. And arguably, it best serves users in buildings in which most workers use desks in walled offices or modular-furniture workstations. The physical layout of such a cabling system is fairly standard, and in most cases, few environmental factors impact the system's performance.
But there is an entire population of cabling-system users whose environments are not so docile. The physical layouts of industrial facilities can vary widely and, perhaps more significantly, the environmental conditions within many of these facilities have the potential to seriously affect a cabling system's performance. Among those environmental factors are moisture, noise, temperature, and vibration. The TIA intends to address each of these issues in its current project.
That project, the proposed Industrial Telecommunications Infra structure Standard, is the responsibility of the TIA's TR-42.9 Subcommittee on Industrial Telecommunications Infrastructure. The proposed standard's first draft states that its purpose is to specify "a generic telecommunications cabling system for industrial buildings that will support a multiproduct, multivendor environment ... The purpose of this standard is to enable the planning and installation of a structured cabling system for industrial buildings, structures, and campuses."
The draft standard also names the following industry sectors as falling within its scope: manufacturing, processing, refining, drilling, recreation and entertainment, transportation, mining, medical, and customer-owned utilities. Further, it states that it "applies to areas where the general environment causes requirements for special cabling." It then lists those general-environment factors as temperature; humidity; electromagnetic interference, electrostatic discharge, and radio-frequency interference; shock; vibration; hazardous gases; corrosive gases; dust; and liquids.
"Cable plays an important role in immunity and radiated performance," Kish said in his presentation. Among the major factors influencing this performance, he added, are crosstalk, impedance-matching, and losses or gains at key transmission frequencies. Cable jacketing is also important, as it provides resistance to potentially harmful manufacturing chemicals.
As to other environmental factors and their direct effect on cabling products, Kish cited testing that has shown handling cables in extreme temperatures will cause jack failure for standard polyvinyl chloride (PVC) jacket materials. Testing has also indicated that extreme temperatures can affect electrical performance.
At the TR-42.9's most recent meeting, also held in August, representatives of Rockwell International Corp. (Milwaukee, WI) and other organizations proposed a sealed RJ-style interface. The proposed interface has the same form factor as the standard M18 industrial low-voltage interface specified in ANSI B39.5. The proposed sealed connector is positioned as being rugged enough to withstand the harsh typical factors in an industrial setting, such as washdowns with cleaning fluids, electrical noise from drives and welders, temperature extremes, and vibration.
As standards go, work is just beginning on this one. The group's initial draft does not specify link distances nor recognized cable types for either backbone or horizontal setups. Other agenda items for the TR-42.9 group include connector specifications, and telecommunications- and equipment-room specifications.
Other standards
In addition to presenting the latest information on the TIA's efforts on the Industrial Telecommunications Infrastructure Standard, Kish updated the crowd on other goings-on within the TR-42 Engineering Committee. He recalled the history of the TIA/EIA-568A standard, and explained the comprehensive revisions it is currently undergoing.
Since it published 568A in 1995, the TIA has drafted five addenda to the standard. The first dealt with propagation delay and delay skew-phenomena typically caused by different conductor-insulation materials in twisted-pair cables. The second addendum addresses near-end crosstalk (NEXT) within connecting hardware.
Number three refers to cable-bundling requirements and hybrid cable. It says that the worst-pair power-sum NEXT between cables must be 3 dB better than the specified worst pair-to-pair NEXT within any cable.
Addendum number four identifies test methods and requirements for patch cords, and number five gives the performance specifications for Category 5E cabling. Kish referred to Category 5E as "a major improvement in transmission performance over Category 5."
One becomes three
The TIA/EIA-568A standard will soon be three separate documents-TIA/EIA-568B.1, B.2, and B.3. The first of that series will be considered the main document, while B.2 will cover copper-based cabling technologies specifically and B.3 will be devoted to fiber-optic technologies.
In the latest draft of 568B.1, the TIA recognizes Category 5E-not Category 5-for use in a cabling system.
The TR-42.8 Telecommunications Optical Fiber Cabling Systems Subcommittee has already approved 568B.3. Of particular note, the document recognizes 50-micron multimode fiber is a transmission medium. The 568A standard did not. Additionally, 568B.3 recognizes both singlemode and multimode fibers to the work area. And, any small-form-factor connector that meets performance and intermateability requirements can be used in the equipment room, telecommunications rooms, and at telecommunications outlets. When that decision was made earlier this year, it put an end to the much-chronicled debate over which, if any, small-form-factor connectors would be officially recognized by the TIA.
Editor's note: Paul Kish's entire presentation from the BICSI Fall 2000 Conference can be viewed at www.bicsi.org. Kish is senior product manager at NORDX/CDT (Pointe-Claire, QC, Canada), responsible for IBDN systems and standards.