Customer Solutions

Lookout Takes Control of Stucker Fork Water System

Author(s):

Sam Motazedi, EIC Contractors

Industry:

Basic Materials - Steel/ Lumber/ Construction

Product:

Lookout

The Challenge:

Delivering reliable control of a water treatment and distribution system and making the system extremely easy for operators to use.

The Solution:

Using Lookout software to automatically control the processes on a PC-based system and increase operator efficiency.

Introduction
The Stucker Fork Conservancy District, located in Austin, Indiana, treats and distributes water in a seven-county region. The water system consists of an intake pumping station, which extracts raw water from the Muscatatuck River. The intake system delivers the water to a dual-channel treatment plant where it is processed. From the treatment plant, the water is pumped into three water-distribution zones. The water-distribution zones variously include nine elevated water tanks, tank feed control valves, and three pumping booster stations. The tank feed control valves and pump booster stations control the levels within the elevated tanks.

System Design
When the Stucker Fork Conservancy District decided to expand capacity in 1997, it opted to automate the entire process and chose EIC Contractors, Inc. to configure and install its SCADA system.

SCADA Evaluation
As a SCADA systems integrator bidding on the project, we at EIC Contractors had to decide on several options that would ultimately determine the robustness and complexity of the system.
We considered installing programmable logic controllers (PLCs) at the intake pumping station, water plant, booster stations, and at each of the tanks (18 units in all). We could then have written ladder logic to control each of the devices at each station. Each PLC would have connected to a central computer through a conventional UHF radio. With the computer running SCADA software, the operators could have monitored process values and issued setpoint changes to the PLCs.

We chose to find PC-based SCADA software capable of performing the control logic internally, instead of at the remote PLCs. This eliminated the need for ladder logic programming and simplified the editing process when we had to modify the control logic in an installed system. In addition, we could use "dumb" remote terminal units (RTUs) instead of PLCs, lowering the cost of hardware for the district. Additionally, unlike PLCs, RTUs are designed for use in remote telemetry applications and are better suited for this application.
We evaluated three SCADA software packages - Wonderware InTouch, Intellution FIX DMACs, and National Instruments Lookout. We chose Lookout because of its ability to effortlessly perform the required control logic, its flexibility in communications, and its remarkable ease of use compared to the other packages.

Lookout Chosen
We selected RTU hardware from Zetron. Lookout communicates to 18 RTUs through Zetron’s Model 1700 controller using the Modbus protocol through the PC serial port. The controller polls the 18 RTUs over conventional UHF radio.

No control logic actually runs in the RTUs. Rather, Lookout makes all automated decisions. For example, we use the Neutralzone object of Lookout to perform on/off control. Lookout automatically issues open and close commands to the feed valves for the various elevated tanks to maintain each tank’s water level. Operators can also change level setpoints.

We also use Lookout to perform pump lead-lag control at the three booster stations and lead-lag1-lag2-standby control at the water plant. Although we originally expected the Alternator object to handle this function, we had to use a combination of objects including the DataTable, some timers, and Expression objects - because of the lack of I/O, we were actually monitoring for each pump and had to add additional logic to compensate.

System Benefits
One unexpected benefit of using Lookout is the inherent flexibility it delivers within the connections between objects. Object connections can be more than simple data pathways. We created custom logic to pull data from sources within the object connections themselves. We also used the general-purpose Expression object extensively to create complex Boolean logic.

A Lookout feature worth noting - online configuration capabilities. Because we could see our modifications online as we made them, we saved a considerable amount of development and startup testing time. After we installed Lookout at the plant, we could make changes to the graphics and I/O without shutting down the system. The district did not lose any historical data and stayed in control of its process. Typical of a SCADA system, the Stucker Fork application had a lot of repetitive work. Water Tower functionality was the same, as was the functionality of the booster pump stations. Because an object represents each RTU, we defined the tag database of a single RTU and replicated it for each. We accomplished this using the database import/export feature of Lookout.

As for the control logic, we were pleasantly surprised to discover that although most Lookout applications are defined interactively by creating and connecting objects, Lookout also includes a compiler. We first interactively created and tested the logic for one of our booster stations by using the interactive dialogue boxes to create and connect objects. We then replicated the source code that Lookout automatically generated for the other booster stations. We simply rolled all the booster station logic into the rest of our application. We did the same thing for the elevated tank controls.

We saved an enormous amount of time with these development tools. In fact, we implemented the full Stucker Fork application in less than 40 man-hours - defining all the control logic, historical data collection, alarming, custom graphics, trending, and security.

Conclusion
The Stucker Fork project has run Successfully for more than a year now. It has had no crashes and communications are completely reliable. The district has asked us to expand the Lookout application and add seven more RTUs.

We have implemented five Lookout SCADA projects following this same model. Four of the five districts require project expansions and we have received an order from a sixth district. We are definitely continuing to use Lookout.

For more information, contact:

Sam Motazedi

EIC Contractors, Inc.

800 Sweet Street

Brownstown IN, 47220

Tel: (812) 358-3513

Fax: (812) 358-3515

E-mail: eicsamm@hsonline.net

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