We recently explored a wireless hazard monitoring option and discovered some interesting results compared with a wired system. In this study, both systems were strictly monitoring with no interlocking equipment. However, both systems had the capability to be interlocked for equipment shutdown. The wired system required a twisted pair cable for each device that ran all the way from the control panel to each device. The wireless system required remotely mounted antennas to allow for a line of site communication between point A and B.
Case 1: 4-leg feedmill
In the first case, we examined a four-leg feedmill. The wired system required 1,000 feet of conduit, whereas the wireless system required none—although the wireless system did require 400 feet of free-aired antenna cable. With the wired system, a large lift or crane would be needed to run conduit to the top of a 120-foot leg. The wireless system completely eliminated the need for a large lift or crane. Additionally, the wireless system eliminated the need to run a conduit above a busy traffic lane on the job site.
The wired system would feature an Allen-Bradley ControlLogix programmable logic controller (PLC) with PanelView display; the wireless system would feature a manufacturer-supplied control unit with touchscreen display. Both systems have the capability of interlocking for leg and feed conveyor shutdown.
The total cost of a turnkey wired system would be $100,000, while the turnkey cost of the wireless system would be roughly half that at $55,000. Overall, the wireless system appeared to be a much more efficient and cost-effective option.
Case 2: 7-leg ethanol plant
In the second case, we examined a seven-leg ethanol plant. The wired system required 3,000 feet of conduit. Although the wireless system required no conduit, it did require 800 feet of free-aired antenna cable. Similar to Case 1, the wireless system completely eliminated the need for a large lift or crane that would have otherwise been required to run conduit to the top of a 110-foot leg. The wireless system also eliminated the need to run long runs of conduit and wire from opposite ends of the plant.
The wired system would feature an Allen-Bradley ControlLogix PLC with PanelView display and the wireless system would feature a manufacturer-supplied control unit with touchscreen display.
The wired system would cost $270,000, while the wireless system would be $65,000. Again, the wireless system appeared to be a much more efficient and cost-effective option.
Conclusion
After reviewing two separate case studies comparing a wired hazard monitoring system to a wireless option, the wireless system appears to be a good choice. It is important to explore all options and determine what type of hazard monitoring system is the best choice for your needs. When evaluating hazard monitoring systems, check out wireless options because the technology has greatly improved and cost has significantly decreased, making it a competitive option.
Adam Dittbenner is service manager, Interstates Construction, at Interstates Control Systems Inc., a certified member of Control System Integrators Association (CSIA). For more information about Interstates Control Systems, visit its profile on The Industrial Exchange.
