ABB has announced that it will equip the 900MW Nant de Drance pumped-storage plant in Valais, Switzerland with six generator circuit breakers and transformers.

ABB will supply its HECPS-3S generator circuit breaker technology for the project, which is located on the Swiss-French border between Martigny and Chamonix. Specifically designed for pumped-storage applications, the HECPS-3S is also in operation at the pumped-storage power station Linth-Limmern, in Switzerland.

"The GCB system and the IPB to the six generators form a ‘protective switch’ which can interrupt the current in case of any short-circuit within 70 milliseconds, avoiding damage to the cavern," explains ABB.

Circuit switching and nominal power shutdowns can occur up to 2000 times per year during normal operations, ABB said.

ABB will also supply 170-ton transformers for the project, which poses a unique challenge as they will need to be transported from the factory, through narrow mountain passes into an underground rock cavern.

The $2.2 billion Nant de Drance pumped-storage project is being developed by Nant de Drance SA with its partners Alpiq, SBB, Industrial Works and the Valais Electricity Company FMV.

As part of the project the existing concrete dam of the upper reservoir, which is fed by waters of the Mont-Blanc massif, is being raised by 20 meters to double the capacity of the reservoirs to about 25M cubic metres. The pumped-storage plant, which comprises 6x150MW units, is scheduled to come online in 2018.


Photo: The new pumped-storage power station will be located in Nant de Drance (Courtesty ABB)