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By Dan Hebert, PE, Senior Technical Editor
Wireless communications in industrial facilities have moved decisively to become a practical solution. Practicality for industry means saving money without taking undue chances, and wireless has advanced to the point where it delivers concrete benefits with manageable risk.
The most obvious cost savings for wireless are delivered in installation, especially for projects in existing plants. It takes lots of money and time to dig trenches, lay conduit and pull wires. Even for above ground installations, the costs of conduit and wiring are often substantial.
Savings over and above lower installation costs are realized during operations because of reduced maintenance costs and greater flexibility. Wireless is cheaper to maintain because there no wires or cables that can be damaged. Wire and cable damage can occur through accidents such as lightning strikes, contact with moving in-plant equipment and inadvertent cutting during unrelated construction activities.Normal wear and tear of wire and cables is most prevalent with connected components that move such as those mounted on cranes, material handling equipment and robot arms. Wiring and cabling to both moving and stationary components also can suffer wear and tear through corrosion, insulation breakdown and degradation due to temperature changes.
Another key advantage of wireless is flexibility. Once a wireless network is installed, the cost of adding another device is very low. Need an extra I/O point 2,000 ft from the control room? No problem with wireless, but very expensive with a wired system.
Wireless saves costs during installation and throughout the operational life of the control and monitoring system, but these savings are accompanied by the risk of implementing what for many is a new technology. Many users get around these risks by limiting the scope of the wireless system in terms of bandwidth, criticality and other parameters.
In most instances, it is cheaper to install a wireless system than its wired counterpart. "We were hired by a major steel producer in the Midwest U.S. to replace the DCS controls on four large boilers that supplied steam to its steel making process," says Timothy Stout, PE, manager process systems for system integrator Matrix Technologies (www.matrixti.com) in Maumee, Ohio. "Wireless saved money because it replaced very long conduit and cable runs of up to 2 miles. This saved miles of conduit and wire which equates to several hundred thousand dollars in installation costs."
Another long-distance application that resulted in substantial savings is detailed by Michel Dubé, automation coordinator at the Montreal facility of Para-Chem (www.parachem.com), a manufacturer of coating, emulsion polymers and adhesives. "We implemented remote monitoring with security cameras via a Wi-Fi wireless system. The monitored site is 1.2 km away from our security office, so we saved an estimated $200,000 Canadian on fiberoptic cables and installation," relates Dubé.
Wireless also can save money on a smaller scale. "We have used wireless to connect portable and stationary label printers," notes Harry Pettit, manager of systems and infrastructure engineering at Pepperidge Farm (www.pepperidgefarm.com), headquartered in Norwalk, Conn..
"Wireless provides flexibility in equipment location that you don't get with hardwired, and we also estimate installation savings at $1,500 per printer," adds Pettit.
Wireless not only saves money on installation labor, it also can cut design costs. "With wireless, engineers don't need to sort through rolls of schematic diagrams, installation and termination details, and the drawings for the fabrication and layout of the cable tray, conduit, junction boxes and interface panels," observes Joe Bingham, president and CEO of system integrator AES Global (www.aesglobal.com), Anaheim, Calif.
Installation savings for wireless compared with wired are often obvious, especially where long distances must be spanned. But in many instances, operational savings due to wireless are just as important.
“Since going to the wireless system almost three years ago, we have replaced only one bolster cable, whereas in the past we would have to replace one every other month.”
Gestamp Automoción (www.gestamp.com) is a Tier 1 Spanish-based automotive supplier with 56 production centers in 17 countries. Its facility in McCalla, Ala., implemented a wireless Ethernet link from ProSoft Technology to connect a ControlLogix programmable automation controller to I/O for a press-stamping application.
"Since going to the wireless system almost three years ago, we have replaced only one bolster cable, whereas in the past we would have to replace one every other month," says Mike Mullins, press maintenance team leader at Gestamp.
Wireless allowed Gestamp to reduce downtime associated with cable failure and replacement, translating to savings of up to $174,000 per year plus the value of parts produced during that time, says Kevin Zamzow, ProSoft Technology's (www.prosoft-technology.com) strategic product manager for wireless technologies.
Wireless technology also can help manufacturers reduce the skill set required for maintenance tasks. "Most maintenance issues are mechanical problems," observes Cliff Whitehead, manager of strategic applications at Rockwell Automation (www.rockwellautomation.com).