Major control system upgrade completed at Corus

Major Control System Upgrade Completed At Corus A major control system upgrade and refurbishment programme, involving the large scale replacement of obsolescent process controllers and associated signal conditioning modules, was completed recently at Corus Colors Shotton Works on Deeside. The project, which involved the replacement of over thirty 14-year old Eurotherm S6000 controllers, was undertaken by Eurotherm engineers working with Corus technical staff. The project was completed working against the clock within a scheduled 7-day annual shut-down period. Corus Colors, a member of the international Corus Group, produces a variety of coated steels for different applications at Shotton, including domestic consumer products, automotive manufacturing and the construction industries. The system upgrade, at the No.5 Galvanising Line, was completed without loss of scheduled production, and resulted in a flawless start-up on the first day after the shut-down period. The line control system at Shotton was based on thirty two Eurotherm S6000 programmable controllers, and two S6000 intelligent data acquisition units. All these instruments had bespoke applications programmes developed and installed to provide the precise requirements of the process. Eurotherm first introduced the S6000 range in the early 1980s and it has continually evolved to take advantage of new technology developments. Whilst it has proved over time to be one of the most reliable control products ever manufactured by the company, because of the rapid advance of chip technology during the last decade, key integrated circuits within the S6000 are now getting difficult to source and the product support lifetime of the instrument has become very limited. The carefully planned Corus project was therefore designed to replace all S6000 instruments on the line with state-of-the-art T640 Integrated Loop Processors, and at the same time to upgrade system software, power supplies, signal conditioning modules and the supervisory control system. This allows overall management of the galvanising process via process mimics within the control room. A key factor in the choice of new T640 Processors was their ability to communicate via the same Eurotherm RS422 BISYNC communications links used by the original S6000 instruments. This meant that no changes were required to the supervisory control system. The T640 is a versatile, multi-loop controller configured for continuous control using a powerful set of function blocks to reproduce exactly the application configurations which existed in the original type S6000 instruments. The T640´s block structure architecture, supported by graphical configuration tools, makes complex continuous control strategies easy to develop and maintain, and configuration is achieved using Eurotherm´s proprietary LINtools software. Because of the scale of the Shotton system, and the physical complexity of cabling, a carefully structured approach was necessary for the large scale replacement of controllers. Eurotherm engineers began the project by taking backups of all individual instrument software, as well as supervisory instrument databases and a detailed poll of the communication system. Corus technicians then undertook a comprehensive wiring survey, in which each termination cable to the instruments was identified, marked, and then reviewed. Proving that the functionality of the new T640s matched that of the old S6000s prior to site installation was a key requirement for project success. Eurotherm´s wide experience in configuring hundreds of large S6000-based systems has resulted in a comprehensive understanding of the subtleties of control system functionality, the final proof of which was testing the new control strategy functionality using a ´black box´ approach. Test equipment in this case included S6000 instruments downloaded with copies of the original S6000 software, sited next to the new T640s. The same signals were then injected into both S6000 and T640 instruments to verify that output states on each T640 matched that of the S6000 instrument to be replaced, prior to installation. During the instrument replacement phase only one S6000 instrument in each of the four line control enclosures was replaced at a time. This was done to avoid potential cabling confusion caused by numerous instruments being disconnected in the same enclosure at the same time. Once each S6000 had been removed it was clearly marked to display its previous location and function. Each replacement T640 was then installed and wired up, and a ´confidence´ testing´ routine implemented to ensure that I/O, communications and display functions were operating correctly. The same ´fail-safe´ approach was taken during replacement of Signal Conditioning Modules (SCMs). Wiring to old Eurotherm ´D´ Series SCMs was fully identified and marked, then modules were replaced by units from the current Eurotherm ´Q´ and ´E´ range of SCMs. The core of the existing supervisory control system, a Eurotherm T3500 Tactitian workstation was not replaced, but augmented by a brand new T800 Visual Supervisor and associated 2500 I/O controller to ensure optimum performance and future upgrade capability. The retention of the T3500 system ensured that operational staff remained familiar with operating sequences, and only minimal operator training was required. In order to complete the project within Corus´ 7-day annual shut-down, Eurotherm engineers and contractors implemented a 24-hour working pattern, in 12 hour shifts. Following cold testing on the days leading up to hot commissioning on the first day after the shutdown, the line started at 8.00 am and was producing quality galvanised product shortly after noon of the same day. Tim Rowland, Corus Colors´ Project Engineer and Andy Martin, Corus Colors´ Automation Technician, are delighted that the project ran so smoothly, and that production was resumed on schedule with no product wastage or delays. Tim Rowland comments: "This was a real ´textbook´ engineering operation, in which a large scale production process received ´major surgery´ within very tight time constraints. The technical and site support provided by the Eurotherm engineering team was impressive, and we have been very satisfied with the way in which the line control system has performed since the project was completed."