The high price tag is not the only explanation for the reluctance among manufacturers to bring their obsolete distributed control systems (DCSs) into the 21st century. Time also can be a huge problem—especially at facilities such as the waste-to-energy plant that American Ref-Fuel Co. operates in West Wareham, Mass. Juggling maintenance schedules there to stop all three boilers and both turbines at the same time is a big enough challenge, without the added problem of keeping them off long enough to replace the control platform.
Although other power companies on the grid could take up the slack if the American Ref-Fuel plant took both of its turbines off line, the waste-to-energy plant must contend with a complication that other power producers don’t have. “We process about 3,500 tons of municipal waste every day,” explains Jim Haselbauer, a controls engineer at the plant. “So we have to keep things moving.” So even while the turbines are off, the company must keep at least some of its boilers working so it can continue to process the waste. Maintenance normally schedules one short outage per boiler per year and works quickly to bring it back into production as soon as possible.
Nevertheless, the need for new technology recently was becoming urgent. Unscheduled downtime and the cost of maintaining the old and weary system had been rising steadily over the years. Moreover, getting spare parts for the legacy system from Westinghouse had become difficult, and contracting third-party sources to rebuild the circuit boards had become necessary, because replacements were no longer available. It was no wonder that the specter of a significant failure had been haunting management and the engineering staff for a while.
Pain-free
American Ref-Fuel found itself in a situation that many other companies are facing with the automation that they installed during the 1980s. The platforms have just about outlived their usefulness, yet the companies have neither the time nor the money to rip out and replace hardware that is still in service. Only now that the platforms have aged to the point where they are hurting profitability, engineering staffs are looking aggressively for economical and reasonably pain-free methods for migrating to new platforms based on the latest technology and current standards.
Thankfully, a number of automation suppliers have responded to the growing need by developing some options. In American Ref-Fuel’s case, the best option was the Plug-In I/A Series system, an approach to platform migration from Invensys Process Systems, of Foxboro, Mass. “We used the Plug-In migration because we could just pull the old cards out and replace them with new cards,” says Haselbauer. “We didn’t have the luxury of doing any wiring changes.”
The concept allowed engineers to make the migration within 18 hours, the most time that management could spare for scheduling the entire plant to be down. By switching only the electronics and leaving the infrastructure of wires and racks intact, the migration team was able to complete the physical switchover in a couple of hours. It spent the rest of the time to verify that connections were correct and that the dampers, control valves and other components worked.
The migration was fast and reasonably priced mostly because Invensys borrowed the plug-and-play concept from the personal computer (PC) industry. “The PC industry was fairly mature in its thinking, recognizing that pieces would change over time and would need to be easily replaced,” observes John Eva, vice president of customer service at Invensys. “The automation industry didn’t have that foresight 20 years ago.”
Realizing the mistake, Invensys is helping industry to rectify it by designing its electronics so it can assemble them in a variety of ways to fit the different legacy DCSs commonly used by industry. Not only do the electronics fit in the appropriate slots, but they also contain the correct plugs at the right places. Reducing the cure to an exercise in repackaging both emulates what standard connections did for the PC industry and makes upgrades affordable and fast. At American Ref-Fuel, the package of new electronics included controls, input-output modules, and operator stations that plugged into the existing wires, chassis and other parts of the old Westinghouse infrastructure.
Plan ahead
Besides the plug-and-play concept, another reason for the success of the migration at American Ref-Fuel was the eight months of planning and preparation that occurred beforehand. Not only did engineers at Invensys program and verify the controllers and human-machine interfaces (HMIs) to the extent possible before installation, but American Ref-Fuel also trained its operators on the new interface so they could use it immediately. Technicians also installed the new consoles and staged the control cards near their points of installation to ensure that the migration would be smooth and fast enough to occur in the allotted time.
Haselbauer is glad that his company made the migration to a modern platform. Since putting the system in place in January, the plant has not had any forced downtime due to the DCS. With the old technology, the plant would have already had at least one occurrence. The added benefits are that its spare parts inventory is less than 10 percent of what it was, and the standards in modern electronics will make future upgrades much simpler. “We don’t foresee getting caught in the trap that we were in previously,” he says.
Another advantage of retaining the old infrastructure is that companies can continue to use the overall control strategy that they already had designed, built and proven over the years. They need not spend the money and time to re-engineer it from scratch and to train the operators to use it. “The highest value asset is the engineering that enable the electronics to control a process, not the physical hardware,” says Eva. He compares the value of the engineering to that for a set of applications developed for Microsoft Excel. The value is the energy and time put into making the spreadsheets, not the software. Moreover, users expect later versions of Excel to run their spreadsheets.
Such analogies with the PC industry are becoming increasingly apropos because the market is forcing vendors of industrial automation to adopt the plug-and-play and commercial off-the-shelf strategies governing technical development in that industry. Because of today’s competitive business climate, industry has been reluctant to scrap the $65 billion worth of legacy systems that the ARC Advisory Group Inc., of Dedham, Mass., estimates are supervising the world’s manufacturing facilities.
“Thirty years ago, customers would have either bulldozed entire facilities or moth balled them and built new plants,” notes Stacey Jarlsberg, a research and development engineer at Siemens Energy & Automation, based in Spring House, Pa. “In today’s global economy, customers need to leverage what they have.”
The types of automation projects that manufacturers are pursuing reflect the situation. About 90 percent of the automation projects in the United States and about 70 percent of those in Europe are expansions, not new installations, according to the ARC study that Jarlsberg cites. Because of the success of plug-and-play in the PC industry, manufacturers want the ability to upgrade their DCS platforms both now and later. “They are looking for open systems that adhere to international standards,” says Jarlsberg. “They are looking to preserve their existing assets and intellectual property.” They also want to connect manufacturing systems to enterprise management systems.
Consequently, vendors must not only incorporate PC technologies into the products but they must also find ways to connect their products into the existing base of legacy systems. In Siemens’ case, each of its DCS components—field devices, field wiring, field termination, input/output (I/O) modules, controllers and the HMI—has its own set of adapters, software, and other conversion tools to let them plug into legacy systems.
For the Simatic PCS 7 DCS, for example, Siemens’ engineers created engineering libraries containing code that gives programming controller algorithms the same look and feel as programming the old system. “So if you’re used to a motor control block or a valve object in the old system, PCS 7 has the same object with the same interlocks, set points, gains and other functions,” says Jarlsberg.
Another example is the PCS 7’s new field termination assembly boards, which have the same form, fit and function as the legacy boards for the Honeywell TDC-3000 DCS. They have the same size terminal blocks and mounting-hole dimensions. The original, wired terminal blocks are simply disconnected from the Honeywell boards and then reconnected to the Simatic boards, which are in turn connected to the PCS 7’s I/O modules. Consequently, the migration takes only a few days.
Evolution vs. Migration
Rather than referring to its strategy for updating DCSs as migration, ABB Inc., of Norwalk, Conn., prefers to call it an evolution, because it relies on incremental improvements. “It is not a not crude rip-and-replace exercise, but a well thought out plan to allow our customers to adapt new capabilities at their pace, according to their needs—adding capability, not replacing it,” says John Murray, vice president of OCS product management. “Evolution allows our customers to do more with what they have over time.”
The incremental approach allows users to upgrade in stages. At each one, ABB’s engineers help users to select from a range of options, matching their investments to the need at hand, yet building the means for later upgrades into their systems. “This philosophy allows users to improve productivity continuously through step-wise extensions of their automation systems, and to take advantage of new technologies as they become available,” says Murray. Not only does it let them reap even greater dividends from their previous investments in infrastructure and engineering, but it also prevents them from hitting the brick wall of obsolescence.
For this reason, Murray urges users of automation to upgrade their systems incrementally and regularly to keep risk and cost to a minimum. “Over time, aging technologies become more difficult and costlier to maintain if you don’t keep up with regular incremental upgrades,” he says. Ideally, the investment should occur at the point where the costs of lost production and rising maintenance exceed the cost of the upgrade.
Phases and Stages
To avoid these problems, Baltimore-based Constellation Energy Group Inc. is following the advice offered by Murray and other experts. The 185-year-old power company is collaborating with Emerson Process Management’s Power & Water Solutions group to upgrade six legacy DCSs incrementally at three of its plants in Maryland. Engineers from both companies have been working together over the past few years to install new controllers and operator workstations on six units during regularly scheduled outages.
The migration on each unit is from Emerson’s WDPF control systems to Emerson’s Ovation Expert Control System, a modern system that uses standard, off-the-shelf hardware and software applications. Emerson designed the Ovation system to offer a migration path that users of its WDPF systems can follow to retain much of their prior investment in hardware and engineering. “This lets us increase the functionality of our control systems in a cost-effective way,” says William Collins, a control system analyst at Constellation.
To maximize functionality and minimize cost, Emerson offers users help in developing the best short- and long-term process automation strategies for their plants through its System Life Assessment Program. “We were able to tailor our migration strategy at each unit to satisfy our operational and financial requirements,” Collins says of the program. For the first project in June 2003, for example, the parties replaced eight controllers, two data link servers and eight operator workstations during one scheduled outage at Unit 1 of the coal-fired C.P. Crane power plant in Baltimore County. The 190-Megawatt unit was up and running in just a few days.
During consultations with Emerson, Constellation decided on a similar one-outage upgrade for Unit 2 at the same plant for last fall. A two-step migration plan, however, fit the H.A. Wagner and Brandon Shores plants better. So each one would upgrade two of its units, replacing a total of 24 operator stations during Phase One in 2002 and 2003 and a total of 41 controllers during outages during Phase Two in 2004. The final stage of Phase Two will occur in October, when Unit 1 at the Brandon Shores plant will receive 16 new controllers.
For Constellation and others, breaking the project into steps has been the key to finding the time and the funds to exploit the latest technology without seeing their past investments go south.
For more information, search keywords “migration” and “upgrades” at www.automationworld.com.
