PROJECT: PLC Controlled Power Plant Restart

The owner/operator of this power plant consisting of two small 50 MW fossil fueled steam turbine/generators had within the last year completed a control system upgrade from pneumatic controls to a fully integrated PLC controlled plant (vs using a DCS). The owner had chosen to upgrade their original controls using Allen-Bradley PLC's on a ControlNet communciation system between PLC's and PC's running Wonderware HMI software on Windows 2000 OS. The project went well with successful commissioning.

Engineering and management services were brought in when the whole Allen-Bradley system crashed and the local talent could not determine the cause or resolution. These services used the in-house technicians, operators, and one Rockwell field service employee to resolve the problem. This team systematically isolated the multiple areas of possible problems and determine that one single PLC processor source file was corrupted. These engineering services used an auxiliary program to convert/export the corrupted file to text and then back/import it into the source file to clean up the corruption. (Obviously, the site had not done a good job of maintaining backups)