Connection to the MV utility distribution network

Schneider Electric - Electrical installation guide 2008
The term "medium voltage" is commonly used for distribution systems with voltages above 1 kV and generally applied up to and including 52 kV (see IEC 601-01-28 Standard).
In this chapter, distribution networks which operate at voltages of 1,000 V or less are referred to as Low-Voltage systems, while systems of power distribution which require one stage of stepdown voltage transformation, in order to feed into low voltage networks, will be referred to as Medium- Voltage systems.
For economic and technical reasons the nominal voltage of medium-voltage distribution systems, as deined above, seldom exceeds 35 kV.
Substation design