SCADA Systems Enhance Reliability of Remote Installations
"Out with the old, in with the new."
Often that’s the approach when upgrading technology. But a total system replacement is an expensive proposition – especially when some elements still may be working well.
The city of Rome, Georgia, faced this dilemma when they needed to upgrade an existing Supervisory Control and Data Acquisition (SCADA) system used in the municipality’s water treatment facilities.
The SCADA system and Central Terminal Unit (CTU) are located at the city’s water treatment plant. A portion is used to control the water distribution system’s pumps and tanks. But most of the remote terminal units (RTUs) are found at lift stations throughout the wastewater collection operation. Prior to the installation of the original SCADA system, an inability to monitor status and control pump activity at lift stations caused overflows during heavy rains. This resulted in EPA fines.
That first wireless SCADA system utilized Motorola’s INTRAC RTUs (Remote Terminal Units) and, to a greater extent, resolved the conflict with the federal agency . By the mid-1990s, these in-place units were still functional, but were no longer being specified to accommodate system growth.
Population changes pushed the need to expand the system, but municipal planners defined a need to preserve the investment in existing equipment while incorporating new technology. Revere Control Systems, a Motorola MOSCAD value-added reseller, with headquarters in Birmingham, Alabama, was given the challenging task of designing and installing such an integrated system.
A key factor in Revere’s selection was the company’s established reputation for quality service. In keeping with this, prior to design of the new system, Revere’s project engineer conducted a series of meetings with city personnel to accurately define the customer’s needs as well as feature requirements.
Revere determined it was possible to integrate the INTRAC units with newer technology Motorola MOSCAD models. MOSCAD units are intelligent RTUs with a microprocessor base that can be programmed to fit most reporting requirements. Linking INTRAC and MOSCAD required passing both signals through a CTU made up of two Motorola Series 300 CPUs.
Communication with the INTRAC units takes place via an MIRI modem, while communication with the MOSCAD RTUs is done with a DPSK modem. Using MODBUS protocol, the information collected from the RTUs is fed to the CTU where it is integrated and interpreted to identify alarms or display activity graphs using FIX DMACS software. Communication channels for the RTU-to-SCADA connections are provided over a trunking system that handles all of the city’s radio traffic.
The original project performed by Revere in 1996 involved integrating six MOSCAD units with the existing ten INTRAC units. Over the past four years, Revere has been called on to provide an additional eight MOSCAD RTUs. As many as two dozen more RTUs will be added over the next few years to manage the growth of the city’s water and wastewater treatment systems.
With the implementation of the upgraded SCADA system, the city has been able to virtually eliminate overflow events. That has resulted in the elimination of something else … EPA fines.
Motorola designed MOSCAD as an expandable SCADA system that can help enhance the performance and operational reliability of remote installations. Thousands of these systems are in operation worldwide, in applications including water utilities, electric utilities, the oil and gas industry, and public safety agencies.
For further information, phone 800-247-2346, fax 847-725-4244, visit www.mot.com/MOSCAD.