Changing the structure of existing networks with regard to the voltage levels and network configuration

The TIWAG (Tiroler Wasserkraftwerke AG) with its rural structure of supply operates two medium voltage levels with nominal voltages of 10 kV and 25 kV. There were two possibilities for selection: 20 kV or 30 kV. Considerations of the technical/economical arguments showed that 30 kV would be the better solution for the future. The measures which prepare the reconstruction process were fixed and considerations about the reconstruction process were made. The technical and commercial backgrounds and decisive factors for the choice of the medium voltage level of 30 kV and for the adjustment of both the medium voltage levels of 10 kV and 25 kV, which were in competition, are described. Additionally, the assigned time scale for changing the operating-voltage from 25 kV to 30 kV and from 10 kV to 25 (30) kV are also described