3. Technical features of the position

3.1 Isolation coordination

Électricité de France's distribution network has two high-voltage levels, 63 kV and 90 kV. With a view to standardization, and in particular to reduce the cost of the modular indoor substation, a study was carried out to coordinate insulation levels, with the aim of defining a single substation with the same insulation level for both voltages. For technical and economic reasons, the choice was made for 63 kV insulation, with additional protection measures to cover the case of substations installed on the 90 kV network.

The performance levels specified are as follows:

• phase-to-earth lightning strike insulation level: the use of zinc oxide arresters reduces the lightning strike insulation...