In terms of voltage, electrical networks can be divided into:
- LV - low-voltage (up to 1kV),
- MV - medium-voltage (1-35 kV),
- HV - high-voltage (110-400 kV).
In LV networks, the most common voltage in households is 230/400 V, and the industry also uses the following voltages: 400/690 V, 500 V, 750 V and 1000 V. MV networks in Slovenia have standardized voltage levels: 10 kV, 20 kV and 35 kV. The voltage levels of 1 kV, 3 kV and 6 kV are used in the industry, mines and for railways. Also, there are generator voltages, such as 6.3 kV, 21 kV etc.
In Slovenia, the high-voltage network is managed by ELES as the transmission system operator. The Slovenian high-voltage transmission network is composed of facilities for three voltage levels: 400 kV, 220 kV and 110 kV. The high-voltage transmission lines of the transmission network (400 kV, 220 kV or 110 kV) transmit electric power to transformer stations (TS).
Noteworthy: seven dual-system 110 kV transmission lines equal one single-system 400 kV transmission line.
Source: Rožman, Robert. 2013. Prenos električne energije. Krško: Zavod Neviodunum.