How Expanding an Existing Wireless Network to Over 1km Cut Project Time and Cost

Emerson’s B.J. Peltier and Jennifer Hejl of Emerson local business partner Puffer-Sweiven team up to tell the story of a petrochemical manufacturer’s need to extend their wireless network. Their abstract describes the facility as having:

…a remote water treatment plant (WTP) located an estimated 3,375 feet south of their main facility. A series of measurements are monitored and setup to alarm back to the main plant. These alarms are wired back to a portion of the plant that is currently being dismantled or demolished and needed to be ‘re-routed’ to a control room at another location in the plant. Being these values and alarms are to be closely monitored and reported, a cost efficient, quick turn-around was greatly needed.

BJ-PeltierB.J. described how the Rosemount 702 Wireless Discrete Transmitter was used. It can take a variety of non-powered switch types such as pressure, flow and level switches as input and pass these discrete input signals back to the control system through the Wireless gateway.

The main plant site was on 200 acres. The boiler house building was being demolished to make room for plant expansions. This was the area the water treatment plant alarms were coming into. Railroad tracks surrounded the water treatment plant so conventional wiring through trenching or overhead cabling was not a good option.

The existing infrastructure included a DeltaV system with wireless I/O card (WIOC) which was the wireless gateway to bring the wireless signals in. With the existing wireless infrastructure in place, B.J noted that it was a “no-brainer” to add the Rosemount 702 wireless devices to bring in the alarm signals.

First a wireless field trial was performed which included a 1420 Wireless gateway, 3 demo transmitters with high-gain remote antennas and placement in locations to provide a good transmission path between the WTP and main plant. The long range antenna can reach 225 meters, the extended range antenna can reach 800 meters, and the high-gain remote can reach 1 kilometer.

Some best practices include scoping to a single process unit, using scaled drawings, network should contain a minimum of 5 wireless instruments within effective range of the Smart Wireless Gateway, considering having 25% of wireless instruments in network within range of Smart Wireless Gateway, making sure each wireless instrument has three neighbors within the effective range, determining effective range by type of process unit and the density of infrastructure that causes obstructions, and considering Gateway capacity.

The AMS Wireless Snap-On planning tool and a Google map image were used to plan the network and location of the wireless devices to achieve these best practice locations. They needed a pressure measurement reading as well and used a Rosemount 3051S transmitter in the mesh network to assist in creating a reliable mesh network. All the devices act as repeaters in the network. The power module life estimator took estimated 8.8 years of service on the batteries based on 8 second update rates.

Some online planning tools you can use are located on the Smart Wireless web page. You can also connect and interact with other people experienced in planning and using wireless technologies in the Wireless track of the Emerson Exchange 365 community.

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