Effects of Inrush Current on Operating Transformers when the Series Resonance Condition is Met

Inrush current often affects the quality of the power system and can interfere with the operation of sensitive electrical loads. In recent decades, studies have focused on controlling this transient current. This paper presents a case study conducted on an in-service transformer where both external and internal electric discharges occurred after several energization maneuvers. The cause of these phenomena has been identified and corrective action has been taken.