In spite of the growing use of digital communication systems - especially those employing optical fibre links for which ABB produces a comprehensive line of equipment - PLC is still often the most cost effective, and reliable, 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, or necessary, to replace it with a digital system in a short space of time. An existing PLC network can often be usefully expanded rather than replaced, and in such cases frequency allocation must be carefully planned to mitigate any channel shortage.