Case Study 118: Scrubbers
Industry Sector: Environmental
Stack emission control system


Square D 784 PLC System

Modicon Quantum Redundant System

Staneco Corporation replaced outdated PLCs with new Redundant Modicon Quantum PLCs for air pollution and dust collection equipment at a power plant. The system was programmed utilizing existing loop drawings along with additional input from client’s engineering staff. The hardware was replaced in a manner which allowed for minimum down time. The existing field wiring was unchanged. Because the new PLC equipment was so much smaller than the original, Staneco came up with a design that added terminal blocks in the same physical locations as the original I/O. These terminals were located on sub-panels along with the new PLC hardware. The terminals were wired to the new PLC I/O. The entire assembly was installed on the existing panel. When the old I/O was removed, the original field wiring was landed back on the new terminals without disturbing the field wiring. This allowed the change to be made in the short outage window.

Since the old PLC hardware was obsolete and replacement hardware becoming harder to obtain upgrading the system was essential to the plant’s operation. The new system provided additional fault monitoring and greater data collection making the process easier to troubleshoot and monitor.