CHANGES OF THE CONCEPT OF NEUTRAL POINT EARTHING OF MID-VOLTAGE GRIDS

Neutral point earthing of mid-voltage grids is implemented variously around the world, depending on the practice of individual countries with the emphasis on the technical regulations in force. Croatia is in the process of transition from star-point earthing through resistors to resonant earthing. Questions on the choice of arc suppression coil technology and the consequences for the operation of relay protection in transformer stations arise in relation to that. It is necessary to view all technical-economic aspects in order to reach an appropriate solution, while at the same time acknowledging the reliable operations of star-point earthing devices, and ensuring a satisfactory quality of electric energy supply.