Fault management in electrical distribution systems

In this report, the different functions and technical solutions of fault management are discussed. The functions concerned are fault detection, fault location, fault isolation and supply restoration. The scope is restricted to the electrical distribution systems in the medium voltage and low voltage domain. The functions of fault management are first studied in general, and their implementation is briefly discussed. The practical implementation of these functions is illustrated by examples from Finland, Italy, Belgium and Germany. Finally, the assessment of the cost effectiveness of fault management functions is discussed and some results, based on practical feasibility analysis are given. It is shown, that in medium voltage overhead networks, a full scale network automation including line switch remote control and remote monitoring of fault indicators is often the most feasible solution. In urban underground systems, the possibilities of network automation usually are restricted to the remote reading of fault indicators at the secondary substations. In large distribution systems, the fault management practices can also be improved by distribution data management systems and by the computer systems for automatic trouble call handling.