Abstract

The increase in the need for electrical energy has a direct impact on the loading of distribution transformers which has the potential to reduce the reliability of the electric power system. This study aims to analyze and calculate the percentage of distribution transformer loading at the PR012 Praya Kota Substation to determine the operational conditions of the transformer against the standards set by PT PLN (Persero). The research method used is a quantitative analysis method with mathematical calculations based on transformer specification data, current for each phase, and measured power on the secondary side of the transformer. Data were obtained through field measurements and technical documentation studies. The results showed that the total transformer loading percentage reached 72.44% of the installed capacity of 250 kVA, which exceeded the maximum recommended loading limit of 70%. In addition, there was an imbalance in the loading between phases, with the highest loading on the R phase at 78.05%, while the S and T phases were 69.005% and 70.39%, respectively. This condition has the potential to cause a decrease in the transformer's lifespan and operational disruptions. Based on the analysis results, the PR012 distribution substation transformer remains operating safely, but interphase load rebalancing is required to improve system efficiency, reduce power losses, and extend the distribution transformer's service life.