Water and wastewater treatment plants rank among the facilities most likely to benefit from control system modernization, and one way to maximize that benefit is to improve connectivity. By integrating mobility, equipment data and energy monitoring, a connected plant can optimize manpower, maintenance and efficiency, with the potential for rapid ROI and significant long-term cost reductions.
But to reap that return, you have to get the new system installed quickly, with minimal disruption and little or no downtime. “And by the way,” added Trinidad Cruz, regional account manager, Prime Controls, “A typical plant has a staff of about three people.”
Cruz presented the session, “Prime Controls deploys PlantPAx to improve plant automation and system security” to attendees of the Water and Wastewater Industry Forum this week at the Automation Fair event in Houston. Prime Controls is the third-largest integrator in the U.S., based near Dallas in Lewisville, Texas.
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Before Cruz began, forum moderator Kevin Hurdle, industry manager, water and wastewater, Rockwell Automation, described today’s business drivers for connected water treatment plants:
- Implementing smart water solutions would save the industry $7.1-12.5 billion
- More than half of utilities have not assessed the vulnerability and resilience of key assets with respect to cybersecurity
- By 2050, 86% of developed countries (64% of developing) will be urbanized, increasing demand for smarter, more sustainable facilities
- Current annual cost of unscheduled downtime is $20 billion
- Nearly three-fourths of North American plants are more than 20 years old
- $65 billion of the global installed base of automation systems is reaching end of life
For these reasons, the digital plant has become a business imperative, Hurdle said. “New technology is not just the latest and greatest, it helps you out in these other areas.”
Showdown in El Paso
El Paso Water Utilities wastewater treatment plants were facing lost production due to aging control systems. Prime Controls leveraged a PlantPAx DCS to provide a path forward that created a standardized program, reduced downtime and lowered total cost of ownership through modernization and optimization.
The El Paso facilities to be upgraded were its Haskell R Street Wastewater Treatment Plant, which serves central El Paso, and its Robert Bustamonte Wastewater Treatment Plant, serving the city’s east, southeast and lower valley regions. Haskell R Street was built in 1923 with capacity of 28 MGD, 1,500 I/O and a Siemens 505 PLC. Robert Bustamonte was built in 1991, handles 39 MGD, and had 1,950 I/O on an ABB Symphony system. “Not even eBay had parts for the ABB system,” Cruz said. “Haskell R Street was built on landfill and the conduit was breaking, but they would not use wireless.
“Both plants—4,000 I/O—were refitted in six months, with no shutdown.”
The official list of issues and challenges included hardware failures, difficulty supporting hardware and software, Microsoft incompatibilities, serial I/O network issues, lack of redundancy, limited or no expansion capabilities, difficulty upgrading in a timely and cost-effective manner, and expensive support contracts with response times not meeting needs.
DCS versus PLC
El Paso’s system requirements list included robust hardware; redundant local and supervisory control; open architecture with Modbus interface to OEM PLCs; version control, change comparison and automatic backups; historian server for critical data and reports; standard software, hardware and programming across the plants; consistent control system design standards; improved plant automation and system security; minimized spare parts and software; and standardized training for operations and maintenance personnel.
Its project requirements list was shorter, but no less demanding: turnkey delivery, fast-track delivery, minimal or no shutdown time, additional automation for optimization of plant processes and 24-hour support via secured cellular remote access or onsite.
Prime Controls filled the bill with systems based on the PlantPAx DCS. “I used to say that in DCS vs PLC, the DCS rules, but about 10 years ago, I saw vast improvements from Rockwell Automation,” Cruz said.
The PlantPAx distributed control system is “the modern DCS,” added Cruz, who described in detail why they used it. First, the standard Rockwell Automation/Allen-Bradley hardware and software provides reliability and customer confidence, and Integrated Architecture Builder makes it easy to size hardware. “With PlantPAx (DCS), I can size the processor based on the I/O, and the Integrated Architecture design tools do it for you,” Cruz said.
Redundant ControlLogix control systems and FactoryTalk View SE servers provide reliability, automatically backed up by FactoryTalk AssetCentre software for disaster recovery and version control. “If it goes down, can you handle it? Or do you want redundancy?” asked Cruz. With AssetCentre software, you always know where your latest software is. “The server stores all your applications, and you have version control. If it disappears, you bring back up the latest version. It also give you an audit trail—the DCS had this in the 1990s. If someone makes a change and shuts down the plant, you can see what they did.”
Prime Controls used an Ethernet Device-Level Ring (DLR) topology to communicate with chassis-based Remote I/O. “With ControlNet, you have to schedule to add I/O. You have to go into program mode and shut it down,” Cruz said. “Using Ethernet DLR, you can bring on Remote I/O without interrupting the process. The communication from the I/O to the processor is the most important in the plant.”
The project used Kepware Modbus OPC Server to communicate to other PLCs, FactoryTalk Historian software for data collection and storage, and FactoryTalk VantagePoint for hourly, daily and monthly reports.
Prime Controls took another page from DCS practice, shortened commissioning and prevented potential equipment damage by using simulation to prove the system. “How do I test 1,900 I/O? You can’t test it on your equipment, you’ll damage it. So use simulation,” Cruz said. Simulation was done on a test system using Studio 5000 Logix Emulate virtual design for virtual PLCs, FactoryTalk SE server, simulation software, and a domain controller.
“We do simulation on 100% of our projects. The DCS world has done that since the 1990s, and the PLC world needs to catch up,” Cruz said. “Before we download it into the plant, we know it works.
