Leakage Flux-Based Method to Identify the Inrush Current in Transformers

Abstract

Inrush current occurrence in the power transformers is an unavoidable event that can happen due to energizing no-load transformer. Although various protection methods based on the terminal current and/or voltage have been proposed for transformer protection, the protection malfunction caused by the inrush current still occurs occasionally. In this paper, By comparing different closing angles of transformers with normal condition and differences in leakage flux near the yoke, a simple and accurate method is presented to identify transformer inrush current conditions. The change of the flux density on the leakage flux sensor can effectively identify the transformer inrush current. This identification method has been initially verified in the simulation in Maxwell.