New SCADA System Reduces Downtime at Omaha Utility

In its case, a failure could not only threaten the drinking water supply of more than 400,000 residents, but also cost the district hundreds of thousands of dollars in penalties.

In order to meet these stringent needs, MUD recently installed a SCADA system from Ci Technologies of Charlotte, N.C. The system uses built-in redundancy to protect data and ensure continued monitoring in case of hardware downtime.

Through a distribution system of over 2,200 miles of mains, the district provides safe drinking water to 164,000 homes and businesses. It also maintains 20,100 fire hydrants throughout the service area.

Water comes from two sources: the 158 MGD Florence Water Treatment Plant, which treats surface water from the Missouri River northeast of Omaha, and the 60 MGD Platte River Water Treatment Plant, which treats groundwater taken from along the Platte River southeast of the metropolitan area. Each plant has its own separate SCADA system. Production of water from the two water plants is monitored and adjusted for predicted demand changes. Most water is pumped a second time at one of the 14 remotely operated pump stations.

Several years ago, the district’s engineering staff predicted that it would need to upgrade the system used to monitor and control distribution. They foresaw a need to improve operating efficiencies, contain maintenance costs, and forestall any interruptions in service that might result from the approaching Y2K concerns.

Huffman Engineering took on the project, building on its prior work engineering and upgrading the monitoring and control system at the Platte River and Florence water plants.

The new MUD SCADA system communicates with 28 Remote Terminal Units (RTUs) in the field via 19 leased lines – faster than dial up modems. The polling speed is limited primarily by the internal modem within the RTU.

Ci Technologies installed a new driver for the RTU hardware, in order to support Huffman’s engineering efforts. The leased line modems are connected to rack-mounted fallback switches via RS-232, and the switches are connected to the RS-232 ports on both I/O servers.

An Ethernet hub for the SCADA system connects both I/O servers, a display client for the water department operator, a display client for the gas department operator, a development/file server node, and the MUD LAN router. Three manager nodes (display only) are connected via the MUD LAN.

These I/O servers handle all I/O, alarms, trends, and reports – with the A unit as primary and the B unit as secondary, prepared to take over without disruption in case of primary failure.

Since the manager nodes are floating licenses, multiple users can access the system from their office computers via the network. Five Pentium III 450 MHz PCs running Windows NT 4.0 were installed in the district control room. They are networked peer-to-peer and connected to the district’s Novell-based LAN.

There are 332 Citect accumulators configured in the project. Many water and gas flows are totalized on an hourly, daily, or monthly basis, with the accumulators updated every second. All operator commands (setpoint changes, pump start/stop, etc.) are logged for future troubleshooting reference.

A "super genie" pop-up screen with many powerful features was created for analog I/O points. When an operator clicks on any analog I/O point on any screen, an analog pop-up screen appears. It displays additional details such as the minimum and maximum range of the selected point. Properties of the point also can be viewed and modified from the analog pop-up screen. The selected analog point can be placed OFF Scan, and a manual value can be entered. The alarming for the selected point can be displayed, and the alarm setpoints and the point’s zero cutoff valve can be modified.

The alarms are configured so that water alarms appear only on the water operator’s screen, and gas alarms appear only on the gas operator’s screen. In total, there are 32 alarm categories configured. All alarms, disabled alarms, and alarms for each ROC can be individually displayed.

The management team has concluded that this new SCADA system has met all of the original objectives. Computer downtime has been virtually eliminated, and tests have proved that switching between the primary and secondary I/O server is seamless.

For further information, contact Ci Technologies in Charlotte, NC – Phone 704-329-3838.