During a pre-study carried out in the 1990’s, it was decided to refurbish the cascade scheme, which is the largest power source in Costa Rica, providing around 25% of the nation’s electricity. The study concluded that two of the three Francis units of the Cachi 100MW plant should be upgraded.

After analysing the study, ICE appointed va-tech-hydro to carry out a contract, funded by the Interamerican Development Bank (IDB), covering the mechanical works and the control system of the modernisation project. When completed, output will increase by 12% and efficiency by 4%.

The study identified that the two oldest units should be upgraded by replacing their mechanical, electrical and electronic parts; only the embedded components will remain, Upgrading will comprise also the third unit’s electronic part to ensure compatibility with the new protection and control system.

VA Tech Hydro will provide two new vertical Francis turbines including inlet valves and three turbine governors. In addition, a drainage and dewatering system will be installed together with a new cooling water system. VA Tech will also provide the erection supervision, diagnosis for the third spherical valve and training for all its supply.

The modernisation work is scheduled to be completed in July 2004.