Swissgrid’s show of confidence

After winning the tender to replace electrical substation AIS 220kV in Fionnay, HYDRO Exploitation was given the opportunity to fulfil the most exacting demands.

Swissgrid’s 220 kV Fionnay-Riddes overhead line was once more able to transport the energy generated at the Fionnay (VS) hydroelectric power plant as of November 2021. Still within the framework of replacing electrical substation AIS 220kV, the Société nationale de transport de l’électricité decided to set up a house load operation mode for the supply of substation GIS 220kV. To do this, a new service building was built in Block B’s cavern.



From electromechanics to electronics 

Following a call for tenders for this assignment, HYDRO Exploitation SA won the replacement mandate to facilitate this house load operation. Winning this contract proved we are capable of meeting the high demands of a company like Swissgrid. 

This project also had a special aspect to it: the house load operation of the new GIS station has a programmable control unit and a touchscreen to manage the substitutions, as well as the visualisation and log of the alarms and events. All of which were managed electro-mechanically to date.

If this project represents a first for Swissgrid, it will certainly serve as an additional reference for HYDRO Exploitation.



The house load operation for the Fionnay substation consists of: 

  • 3 400VAC power supply (supply 1, supply 2, diesel mobile)
  • 1 main 400VAC distribution board
  • 2 400VAC sub-distribution boards (normal and backed-up)
  • 2 110VDC power supplies (2 144A rectifiers, 2 420Ah batteries)
  • 2 main 110VDC distribution boards
  • 2 110VDC sub-distribution boards
  • 1 230VAC UPS with its own distribution board
HYDRO Exploitation SA
Rue de l’Industrie 10
CP 315 - CH-1951 Sion
Contact us
HYDRO Exploitation SA
Rue de l’Industrie 10 CP 750 - CH-1951 Sion +41 (0)27 328 44 11
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