Gabi power plant: designing the electrical installations

The Gabi power plant was completely demolished in the spring of 2022 in preparation for its servicing and to optimise the production of electricity there. Energie Electrique du Simplon (EES) and Swissgrid commissioned HYDRO Exploitation to research the electrical design of a new building that would best accommodate two new 11.6 MVA machines and the site’s numerous electro-mechanical plants.

In addition to the control-command equipment for the units and house load operations, the plant has two MV substations (6.6 kV and 16 kV), two power transformers (24 MVA 220 kV/6.6 kV and 6.3 MVA 16 kV/6.6 kV) with load control, as well as all the HV/MV/LV pipelines and connection cables. Given the limited space within the plant, this was a big challenge to take on.

Renovation and relocation of Swissgrid’s AIS substation

The Gabi site differs from others as it houses Swissgrid’s large 220 kV air-insulated switching station (AIS). This consists of a single area installed on the building’s roof and a 220 kV cable connection to the transformer. The primary section of the existing substation was dismantled and then reassembled on the new building, while the secondary section was completely renovated. HYDRO Exploitation carried out significant work during the research phases in order to provide Swissgrid with a high-quality installation that is both functional and complies with the various standards and rules in force.

The addition of a load-bearing structure for an easy operation

This work was realised in close collaboration with the other technical teams. For the design phase, the mechanical team provided a 3D model of the load-bearing structure and all the electrical equipment installed in it. This highly valuable tool revealed many conflicting issues. The civil engineering team was responsible for sizing the load-bearing structure. They validated its static and seismic resistance, drew up plans for executing the work, and ensured the ongoing monitoring of its construction.

The concept of a load-bearing structure with only four supports on the ground frees up a lot of space and allows for its easy and safe future use. The electrical equipment for the Gabi power plant was installed to the complete satisfaction of the clients, EES and Swissgrid.



HYDRO Exploitation SA
Rue de l’Industrie 10
CP 315 - CH-1951 Sion
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HYDRO Exploitation SA
Rue de l’Industrie 10 CP 750 - CH-1951 Sion +41 (0)27 328 44 11
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