Conclusion
Protection Plan for Medium Voltage Public Distribution Networks

The faults that affect a radial medium-voltage distribution network, whatever the nature of these faults (polyphase or single-phase) and whatever the structure of the network and its neutral regime, are governed solely by intangible physical laws: their characteristics have been known for a long time and are not likely to change. The algorithms that have been developed to detect these faults are well suited to the task, and have proved their worth: they mainly involve detection by amperometric threshold crossing, with or without directional criteria, by voltmetric threshold crossing and by "first transient" analysis (wischer relays). These algorithms have been implemented in equipment whose technology - first electromechanical, then electronic and now digital - has evolved considerably, but without modification.

It is highly unlikely that there will be any major...