Edison, one of Europe’s oldest power companies, which was founded in 1884 in Milano, owns the Fontanamora hydroelectric plant that generates three megawatts (MW) of renewable power from turbines and auxiliary machinery. The plant is situated at Lombardy by a fast-flowing river at the bottom of a steep gorge. Lombardy lies in the north of the country, sharing a border with Switzerland.
As the second energy company in Italy, and a European leading operator with operations in the supply, production and sales of electric power and hydrocarbons (natural gas and crude oil), Edison has a strong focus on renewable generation. It has 7.7 giga watts (GW) of installed renewable capacity, comprising hydroelectric, wind, solar, thermoelectric plants and a biomass system.
At the beginning of 2013, Edison decided to undertake a complete revamp of the plant, with the project including also the step-up of the voltage level of connection to the electricity grid, from medium to high voltage. The customer decided to replace the previously installed switchgear with a new product featuring the latest in switching technology: ABB's PASS hybrid switchgear module, rated at 72.5 kilovolts (kV).
The project was challenging both technically and from an installation perspective, as access to the powerhouse is only possible by way of a steep, narrow stairway down the side of the gorge. Entrance to the powerhouse is small, and the room available for installing switchgear is only three square metres wide.
Solution with innovative design
To cope with these difficult space challenges, ABB leveraged its expertise in switchgear design to supply a hybrid module that integrates a circuit breaker and two disconnectors, plus current and voltage transformers – and the control and protection relay in a single unit.
Plug-in cable terminals instead of traditional air-insulated bushings were deployed to further reduce the module's size, enabling it to fit it in the reduced space of the Fontanamora powerhouse.
To overcome the narrow stairway and minimise transport risks, the installation team secured the PASS hybrid module with special harness straps – and lowered it down into the gorge with a crane. The preassembled unit arrived on site pretested for high-voltage and ready for installation, which took four days. There was no need for the additional equipment typically needed to perform on-site high-voltage tests, so the ABB PASS hybrid module could be put into service without delay, saving time and costs.