Standardising control systems for the water industry

Abstract

Mechanical and electrical systems have developed into more complex interdependencies that, by their nature, require more sophisticated control systems. Industrial computer-based processors, such as programmable logic controllers (PLCs), have been developed to perform control functions and provide the operator with visual information to allow him to operate and control the plant. The PLCs first used by United Utilities had limited functionality and display capability. Nowadays the equipment used typically comprises several networked PLCs and colour human machine interfaces (HMIs) offering both graphical and tabular displays. Connection of the telemetry outstation to the plant control and monitoring system is commonly via the PLC network. The outstation accesses data tables within the PLC memory to avoid the need for costly telemetry I/O and its associated wiring.