By Paul Miller, Contributing Editor
Engineers and technicians in industrial facilities and system integrators are becoming more familiar with fiberoptic networking media as a complement to or replacement for copper cabling and connectors.
A number of myths still surround the technology. Lets explore the validity of some of these myths and look at examples how optic networking technology is used to help solve problems in todays real-world industrial environments, while providing a foundation for future applications.
Myth #1Fiberoptic Cable Is Fragile
When first used in commercial applications in the late 1970s, fiber cabling was not known for its ruggedness. Cable design and construction has progressed since the early days of the technology. While improperly installed fiberoptic cable and connectors still can be more fragile than copper, this is not the case when the appropriate cable, connectors and terminations for the application are selected and the proper installation guidelines are followed.
The top reasons for choosing fiberoptic cable for use in the three Evansville Water and Sewer Utility (EWSU) treatments plants were bandwidth, EFI/EMI immunity and reliability, says Michael Halbig, president of InGen Technologies, a system engineering and process control company in Evansville, Ind., that installed extensive fiberoptic networks in the three treatment plants at the EWSU. The fiber cable delivered everything that was expected. Due to large EMI loads in the facilities, communications errors occurred from time to time when copper media was used. These can be difficult to diagnose and resolve. The fact that there have been no failures in the fiberoptic systems is proof of the reliability.
Fiber has gotten incredibly rugged, according to one of its suppliers. Ive seen someone pulling reinforced fiber cable through a conduit with a backhoe without any problems, says Sven Burkard, marketing manager at Hirschmann Americas. With fiber, you dont have the impedance losses and pair-to-pair crosstalk problems you can have with copper when non-bonded, twisted-wire pairs separate due to improper handling. Ive tied fiber into loose knots without it breaking or causing problems.
Fiber cable is pretty strong, agrees Kevin Burak, a networking consultant at Invensys Process Systems. Youd have to bend it back onto itself before youd have problems.
Myth #2Fiberoptic Networks Are More Expensive Than Copper
This might still be true at the component level, but not when you consider total installed costs. Fiberoptic cable itself often costs more per foot, but certainly not in capacity. You can push more data through fiber, says Burkard. With copper, as speeds go up, the cable tends to get more expensive. This is not usually the case with fiber.
The price of fiber has gone down to the point that the costs are about the same, says Burak. In some cases, some would argue that fiber is even cheaper, he claims. The media converters used in network switches also cost about the same.
Due to its lighter weight, smaller diameters and immunity from corrosion, fiberoptic cable often is less expensive to install and maintain than copper in many industrial applications. Fiber has really come a long way in the 10 years that Ive been in this business, says Burkard. Its no longer a voodoo-like technology relegated to the IT people. Fiber is getting very easy to implement. Once you have a properly terminated fiberoptic connection, youll have far fewer problems than with copper connections.
Myth #3Fiber Benefits Are Limited to Higher Bandwidth, Faster Speeds, Longer Distances and Interference Immunity
The obvious advantages of fiber over copper are more bandwidth, faster transmission speeds , the ability to transmit data error-free over longer distances and immunity from types of electrical interference and ground loops. However, fiber offers a number of less-obvious, but equally significant safety and security-related benefits over copper.
Since fiberoptic cable conducts light pulses rather than electricityas is the case with copper mediayou dont worry about the network causing sparks, shocks or fire, says Burak. As a result, fiber can be used in hazardous areas where copper would be problematic. Fiber also is resistant to the electromagnetic pulses (EMPs) that often follow an explosion. EMPs can cause communications problems, blanking out system screens and making it very difficult for plant operators to deal with the situation.
Fiberoptic networks are more difficult to tap into than copper networks, says Burak. With copper, all you need to do is bring a special radio close to the wire to be able to eavesdrop on a network, he says. Its also much easier for someone to physically tap into a copper network without being noticed. Any tampering of fiberoptic media will become apparent immediately to network users. As a result, fiber networks make it easier to comply with Federal Energy Regulatory Commission critical-infrastructure-protection guidelines.
Fiber is extremely secure and tamperproof, agrees Burkard. The fiber strand itself is so thin that you cant easily tap into it.
Fiberoptic cabling installed at Evansville Water and Sewer Utility plant
Initial costs might be a little higher, but Hirschmann heartily preaches the ROI-of-fiber sermon. With fiber, it doesnt matter which protocol youre transmitting, says Burkard. Be it Ethernet, Profibus, Modbus or whatever the case, the fiber cable you install today very likely will be usable 20 years from now, regardless of the protocols then in vogue. This is not likely to be the case with copper.