UPGRADING WITH LIMITED DOWNTIME
A critical fresh water treatment plant, Borough of Coudersport, required an upgrade to their existing Process Automation Control (PAC) System installed at their north and east plants. Their units were reliable and running great after a decade of service. However, the main processors (T940) were obsolete and Coudersport would not have been able to replace them on failure. This is a rural plant that is two hours from the closest city so without local support, reliability is a high priority. The plant could not be taken offline for more than a few hours at a time
so the majority of the upgrade work was required to be done live. Eurotherm, a division of Watlow, have shown a commitment over the last four decades to continue making hardware and programming software with backwards compatibility to previous generations. Every version of their LINTools software supports EVERY previous
version of EVERY hardware variety for the last 30 years – a significant advantage over some suppliers that require a version of configuration software to exactly match with the hardware version.
In this case, an upgrade was achieved by replacing the T940 processors with T2750 racks allowing for the use of the same communications backbone and existing I/O cards. Owing to the ability to ‘port’ the majority of the code directly from the T940 to the T2750 (despite them being two generations of product development apart), the engineering time was reduced by around 70%. Since the existing I/O was retained, installation costs were reduced by 90% since no new wiring or loop checks were required. Additionally, drawing changes were minimized and because significant portions of code were re-used, the overall risk associated with a live upgrade was minimized. This is a multi-location system with 300 I/O points and the offsite work took just two weeks. Owing to the significant re-use of hardware and wiring, Neal Systems and Eurotherm were able to then remove, replace, and commission the T940 processors and update the SCADA computers in one week.
The plant never experienced downtime in excess of an hour.
During this site week, the three SCADA computers were replaced with PC’s at the latest windows version with licenses to match. A new Ethernet switch was used to connect everything together.
The majority of their existing equipment remained in place. The enclosures and screens stayed the same, and there were no field wiring changes. This reduced the total cost of the project by 70% and the risk by 80%. The operators did not require any training since the system looked and worked exactly the same as before. Interruption to plant operations was minimal and all work was performed during the day shift.