The Chaira Pumped Storage Hydro Power Plant (Chaira PSHPP) was built in the Rila mountains, about Шаблон:Convert southeast of Bulgaria's capital city, Sofia. Chaira has generating capacity of Шаблон:Convert and a pumping capacity of Шаблон:Convert. The power plant is equipped with four reversible Francis pump-turbines, each rated at Шаблон:Convert in the generating mode, and Шаблон:Convert in pumping mode.
Units 1 and 2 have been in operation since 1995, and at that time Chaira was the largest pumped-storage plant in southeast Europe with the highest head in the world for a single-stage pump turbine (Шаблон:Convert generating and Шаблон:Convert pumping). Units 3 and 4 came online in 1999.
The pump-turbines and motor-generators were supplied by Toshiba, and three of them were manufactured under Japanese supervision in Bulgaria. The upper basin for Chaira is formed by the Belmeken Dam which connects to the pumped storage plant by two headrace tunnels with a diameter of Шаблон:Convert and two penstocks with diameter Шаблон:Convert, reducing to Шаблон:Convert.[1] Outflow from the Belmeken reservoir supplies the Sestrimo Hydro Power Plant
