This study analyzes the effect of load unbalance on the efficiency of 20 kV distribution transformers at PT. PLN (Persero) UP3 Palu. Load unbalance is a common condition in three-phase distribution systems that can cause neutral current flow and increased power losses. This directly reduces transformer efficiency, wastes energy, and can shorten the lifespan of the equipment. The research method involved collecting current data from several transformer substations, both under unbalanced load conditions (before balancing) and after load balancing was performed. This data was then used to calculate power losses and transformer efficiency. The analysis results showed that initially,
transformer efficiency ranged from 93.26% to 97.76%. After load balancing was carried out, the neutral current and power losses were significantly reduced. This led to a substantial increase in transformer efficiency, reaching up to 99.97%, proving that load balancing is an effective solution for optimizing transformer performance. This study
concludes that load balancing efforts are crucial for improving energy efficiency, maintaining the reliability of the distribution system, and supporting more economical operations.