Transformer Leakage Flux Frequencies Analysis under Internal Windings Faults

Inter-turn winding faults are one of the most important faults occurs in transformers and if it not quickly detected, develop into serious faults that would result in harmful damage to transformer. In this paper, the effects of leakage flux variation under inter-turn winding fault conditions are studied. To analyze the transformer behavior under inter-turn winding faults, a three-phase transformer with actual dimensions is modelled using time stepping finite element method (TSFEM). For experimental investigation of leakage flux, four search coils are installed on the HV windings of the transformer and the frequency spectrum of search coils are analyzed. Search coils signature analysis for various situations of inter-turn faults and transformer operation are extracted. The obtained results show that leakage flux analysis can be used as an attractive and reliable method for transformer inter-turn fault detection.