A practical Evaluation Method for Inrush Currents and Voltage Dips during Transformer Energization

In this paper, we present a practical calculation tool for evaluating inrush currents and voltage dips during transformer energization. As power system configurations change more frequently with the increasing introduction of distributed and renewable energy sources, understanding these transient phenomena has become increasingly important. Excessive inrush current may trigger unintended relay operation, whereas voltage dips can disturb voltage-sensitive equipment. A simple and accurate evaluation method is therefore required. The tool developed can be used to compute inrush currents and voltage dips using analytical expressions derived from a simplified equivalent circuit, where the transformer magnetizing branch is represented by an ideal switch and a saturated inductance. This approach…