In spite of the growing significance of digital communication systems - especially those employing optical fibre links for which ABB produces a comprehensive line of equipment - PLC still remains in many cases the most costeffective solution to cover the operational needs of a power system. This applies particularly when only low volumes of data have to be transmitted over long distances.
An existing PLC network represents a considerable investment made over many years, and for reasons of cost and system operation it is seldom possible to replace it by a digital system in a short space of time. More often than not, an existing PLC network is expanded rather than contracted and in such cases, frequency allocation has to be planned carefully because of the shortage of channels.
In other instances, a PLC channel is installed as a back-up to increase the availability of im portant new digital channels.
Over decades of successful involvement in the PLC and transfer tripping field, ABB has not only proved its high technical standard and competence by keeping at the forefront of the development and application of the latest technologies in communication and protection equipment, but has also built up a formidable capability in systems and applications engineering.