Unit-4 of Srisailam Left Bank Hydro Electric Station Is Back On Grid After Six-year Repair Saga
The 150 MW unit, part of the 6x150 MW complex, had caught fire on August 20, 2020, suffering severe damage to its stator and rotor. Repair work was split between two firms, Shree Abirami Engineering Works in February 2022 and the Noida-based Voith Hydro Pvt Ltd in August 2021
HYDERABAD: Unit No. 4 of the 900 MW Srisailam left bank hydroelectric station in Nagarkurnool district was successfully synchronised with the state grid early on Tuesday, ending a long cycle of fire damage, repeated repairs and trial failures that began in 2020.
The 150 MW unit, part of the 6x150 MW complex, had caught fire on August 20, 2020, suffering severe damage to its stator and rotor. Repair work was split between two firms, Shree Abirami Engineering Works in February 2022 and the Noida-based Voith Hydro Pvt Ltd in August 2021.
After the first round of repairs, the unit was commissioned on July 29, 2023, but tripped within weeks due to a stator earth fault, damaging stator bars and the core. As the unit was still under guarantee, Voith agreed to redo the stator rewinding free of cost, but sought an additional ₹2.95 crore for rotor lowering, alignment and installation of online air-gap and partial discharge monitoring systems. Work began in April 2025.
The unit was recommissioned on October 2, 2025, but tripped the next day due to an air-gap protection alert. Inspections by Voith and Japanese firm HM Hydro found loosened rotor poles, besides other issues.
Following a review in January 2026, Voith was directed to complete all rectification works. After clearance from the chief electrical inspector, the unit was synchronised at 3.21 am on August 11. Fine-tuning, including dynamic balancing and turbine auto-tuning, is now underway to ensure stable operation.
With all six units of SLBHES now functional, TS-Genco expects improved peaking power support and better utilisation of water releases from the Srisailam reservoir.