Zahra Taghikhani - Department of Electrical and Computer Engineering, Mazandaran University of Science and Technology, Babol, Iran
Abdolreza Sheikholeslami - Department of Electrical and Computer Engineering, Babol (Noshirvani) University of Technology, Babol, Iran
Mohammad Ali Taghikhani - Department of Engineering, Imam Khomeini International University, Qazvin, Iran

It is well known that the magnitude of transformer inrush current depends on several factors such as residual flux which is an important issue in assessment of inrush current in the time and frequency domains. The analysis of single-phase transformer inrush current at different switching angles considering the residual flux has been provided in this paper. Mathematical equations are first applied to solve inrush problem based on iteration and then, as the harmonic domain study is dominant due to the existence of harmonics with different orders, Hartley transform which requires less number of computations is used in this paper. MATLAB code is developed to get the time and frequency domain waveforms at different levels of residual flux with high accuracy and hence the efficiency of the method is verified

Transformer inrush current , Residual flux , Harmonic domain , Hartley transform