The paper presents the evaluation of the magnetization inrush current of some small power transformers, widely used in electronic circuitry. A simple analytical approach is proposed relying on the transient state equations of the transformer’s energizing process along with the corresponding Ampère law applied on the magnetic circuit. Adopting a convenient expression for the electric steel H-B nonlinear dependency, the inrush current amplitude and time variations are predicted. A comparative study over the most common small transformer core shapes in terms of magnetization inrush current features is then performed. Additionally, a critical study concerning the state-of-the-art inrush current mitigation techniques is also carried out.

Keywords: Magnetizing inrush current, Small power transformer, Mitigation techniques