Penelitian ini menganalisis efisiensi termal PLTGU Tanjung Uncang sebelum dan sesudah inspeksi minor pada Steam Turbine Generator (STG) Siemens SST-400. PLTGU, dengan kapasitas total 120 MW, memainkan peran penting dalam sistem kelistrikan Batam - Bintan. Efisiensi termal yang tinggi dicapai melalui penggunaan kombinasi Gas Turbine dan Steam Turbine, di mana panas dari gas buang Gas Turbine dimanfaatkan oleh Heat Recovery Steam Generator (HRSG) untuk menghasilkan uap bagi Steam Turbine. Seiring waktu, performa STG menurun akibat keausan mekanis dan akumulasi deposit pada komponen internal, sehingga inspeksi rutin seperti inspeksi minor diperlukan untuk menjaga kinerja optimal. Penelitian ini mengevaluasi perubahan efisiensi termal dan output daya STG sebelum dan sesudah inspeksi. Hasilnya menunjukkan peningkatan signifikan dalam efisiensi termal dan output daya, serta penurunan heat rate, yang menunjukkan peningkatan efisiensi bahan bakar. Kesimpulannya, prosedur inspeksi minor terbukti efektif dalam meningkatkan performa STG di PLTGU Tanjung Uncang. Rekomendasi yang diberikan termasuk peningkatan frekuensi inspeksi, penerapan teknologi pemantauan modern, pelatihan teknisi dan operator, penggunaan bahan bakar berkualitas, serta evaluasi berkala untuk menjaga efisiensi termal dan performa STG.

This study analyzes the thermal efficiency of the PLTGU Tanjung Uncang before and after a minor inspection on the Siemens SST-400 Steam Turbine Generator (STG). The PLTGU, with a total capacity of 120 MW, plays a crucial role in the Batam-Bintan electricity system. The high thermal efficiency is achieved through a combination of Gas Turbine and Steam Turbine, where the heat from the Gas Turbine exhaust is utilized by the Heat Recovery Steam Generator (HRSG) to produce steam for the Steam Turbine. Over time, the STG's performance declines due to mechanical wear and the accumulation of deposits on its internal components, making routine inspections such as minor inspections necessary to maintain optimal performance. This study evaluates the changes in thermal efficiency and power output of the STG before and after the inspection. The results show a significant increase in thermal efficiency and power output, as well as a reduction in heat rate, indicating improved fuel efficiency. In conclusion, the minor inspection procedures have proven effective in enhancing the performance of the STG at PLTGU Tanjung Uncang. Recommendations include increasing inspection frequency, implementing modern monitoring technologies, training technicians and operators, using high-quality fuel, and conducting regular evaluations to maintain the thermal efficiency and performance of
the STG.