Basics for MV design according to IEC standards
For technical and economic reasons, the service voltage of medium voltage distribution networks rarely exceeds 36 kV.
The connection of an electrical installation to a MV utility distribution network is always realized by means of a dedicated MV substation usually designed "Main substation". Depending on its size and specific criteria, mainly related to the loads (Rated voltage, number, power, location, etc….), the installation may include additional substations designed "Secondary substations". The locations of these substations are carefully selected in order to optimize the budget dedicated to MV and LV power cables. These secondary substations are supplied from the main substation through the internal MV distribution.