Why does a charging hub need its own transformer?

A megawatt at 400 V needs about 1,700 A. At medium voltage the current is a fiftieth of that, so large hubs connect there with their own transformer.

Explained in

Charging infrastructure · Stop 02Why does the grid connection decide so much?From 250 kVA to 1.2 MW: why a fast-charging hub usually needs a medium-voltage connection with its own transformer, and what the grid operator's role is.

The distribution system operator checks whether its grid can carry the new load, offers a connection and builds its part. EU law requires Member States to make connecting charge points easier and requires grid operators to cooperate on a non-discriminatory basis with any company that builds or runs them.

From “What the grid operator does”, stop 02

Terms

  1. DSODistribution system operator: runs the local power grid and connects charging sites to it.
  2. Medium voltageThe grid level of roughly 10 to 20 kV between the high-voltage network and the 400-volt street grid; large charging hubs usually connect here, with their own transformer.
  1. How far apart are fast chargers on EU motorways?Along the TEN-T core network, AFIR requires a charging pool at least every 60 km in each direction: 400 kW by the end of 2025, 600 kW by the end of 2027.
  2. What does it take to build a charging hub?A site host, a grid connection, an energy supply contract, a building permit and backend and roaming partners. The grid connection is usually the slowest step.
  3. What is utilisation of a charger?The energy a charger delivers compared with what it could deliver at full power all year. Because most costs are fixed, it decides whether a site pays back.
  1. EUR-Lex: Directive (EU) 2019/944 on common rules for the internal market for electricity, Article 33. https://eur-lex.europa.eu/eli/dir/2019/944/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.