Penelitian ini berfokus pada evaluasi keandalan transformator daya pada Gardu Induk Talang Ratu, yang terletak di tengah kota dan bertugas menyalurkan listrik ke berbagai objek vital nasional seperti fasilitas kesehatan, pusat industri, perkantoran, dan sarana transportasi. Keandalan transformator merupakan hal yang sangat penting untuk menjaga kontinuitas pasokan listrik dan meminimalisir gangguan pada sistem. Transformator di gardu induk ini telah beroperasi selama 45 tahun dan mengalami penurunan kinerja akibat usia yang telah melebihi standar operasional. Studi ini bertujuan untuk mengevaluasi kondisi transformator menggunakan beberapa metode analisis mendalam tentang faktor-faktor yang mempengaruhi keandalan transformator, termasuk pengujian Dissolved Gas Analysis (DGA) dan pengujian Tangen Delta Bushing. Hasil pengujian menunjukkan bahwa transformator sudah tidak mampu menyalurkan beban secara optimal, hanya mampu menyalurkan 46% dari kapasitasnya. Analisis DGA mengungkapkan adanya gas-gas terlarut dalam minyak transformator, seperti metana (19,471 ppm), etana (22,478 ppm), dan karbon monoksida (147,057 ppm), yang menunjukkan adanya degradasi material dalam transformator. Berdasarkan hasil evaluasi, didapatkan bahwa transformator di Gardu Induk Talang Ratu sudah mengalami penurunan keandalan dan memerlukan penggantian dan peningkatan kapasitas (uprating) untuk meningkatkan keandalan dan efisiensi sistem tenaga listrik.

This research focuses on evaluating the reliability of power transformers at the Talang Ratu Substation, which is located in the middle of the city and is tasked with distributing electricity to various national vital objects such as health facilities, industrial centers, offices, and transportation facilities. Transformer reliability is critical to maintaining continuity of power supply and minimizing system disruptions. The transformer at this substation has been operating for 45 years and has experienced a decline in performance due to age that has exceeded operational standards. This study aims to evaluate the condition of the transformer using several in-depth analysis methods on the factors affecting the reliability of the transformer, including Dissolved Gas Analysis (DGA) testing and Tangen Delta Bushing testing. The test results show that the transformer is no longer able to distribute the load optimally, only able to distribute 46% of its capacity. The DGA analysis revealed the presence of dissolved gases in the transformer oil, such as methane (19.471 ppm), ethane (22.478 ppm), and carbon monoxide (147.057 ppm), indicating material degradation in the transformer. Based on the results of the evaluation, it was found that the transformer at the Talang Ratu Substation had experienced a decrease in reliability and required replacement and capacity increase (uprating) to improve the reliability and efficiency of the electric power system.