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Hoffman Estates

Background

The Village of Hoffman Estates collects data from seven elevated tanks, three reservoirs, two high lift booster pumping stations, five water receiving stations, two inter-zone booster stations, and sixteen sewage lift stations across the Village. The Village of Hoffman Estates had an aging proprietary data collection system that was originally installed in 1986 and utilized telephone line communications. In 2004-2005 redundant SCADA computers running Intellution iFix and an Allen-Bradley SLC505 were installed at the SCADA master. A protocol conversion board was installed to interface the data collection system with the SLC505. All system control and communications management were programmed in the SLC505. The data collection system had limited expandability and was becoming obsolete. The Village often experienced wholesale telephone line failures causing extended down time and high expenses due to staff over time. The entire SCADA system required modernization.

 

Solution

The Village developed a four phase plan that would be executed over several years and would completely replace the existing SCADA system. Phases one and two would replace the data collection Remote Telemetry Units (RTU) with modern Programmable Logic Controller (PLC) based SCADA RTUs. Phase three would replace the telephone communications system with a licensed radio communications system. Finally, phase four is planned to replace the existing SCADA server computers. The Village issued Requests for Proposals for each upgrade phase and invited qualified SCADA system integrators to respond. Automatic Control Services (ACS) provided the winning proposals for Phases 1 through 3 and provided the following equipment and services: In Phases 1 & 2, ACS replaced the outdated SCADA RTU panels with Allen-Bradley Micrologix 1100 and 1400 PLC based panels. These were chosen because they provide both serial and Ethernet communications which would make the future transition from telephone line communications to radio communications simple. These PLCs are economical with sufficient processing power and I/O capacity for this application. The communications management and system control processing is no longer concentrated in the SCADA Master PLC. These functions are distributed across the SCADA network. Each RTU is programmed to manage its own data messages, station control, and alarm functions. Color graphic Operator Interface Terminals (OIT) were installed at each RTU. In Phase three ACS obtained a license for a 150MHz radio frequency and installed Cal-Amp Viper radios and antenna systems at all of the RTU locations. The 150 MHz range was chosen due to the fact that the Village RTU locations are spread across several miles and are divided by forest preserves. The radio master was located at an elevated tank site that provided adequate height with a central location for data. The Village IT department had available fiber optic cables between the SCADA Master and the elevated tank. ACS utilized a fiber optic pair for communications between the SCADA Master and the Master Radio. The 150MHz radio frequency does have limited band width creating the potential for sluggish communications due to overloaded connections. ACS avoided this complication by implementing a communications synchronization scheme.

 

Results

The Village of Hoffman Estates now enjoys a modern and well integrated SCADA system that can be easily expanded and maintained. The Village does not experience communications interruptions. Expenses related to the high initial cost of the radio system installation are offset by the elimination of the monthly telephone line charges and the staff overtime during communications failures.

 

Hoffman Estates Case Study PDF

 

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