Transformer fault analysis using instantaneous symmetrical components

Symmetrical components analysis of time-dependent variables is a well-known tool for calculation of power quality in electrical grids. This paper deals with analysis of power transformer internal faults by means of time-dependent symmetrical components of currents. Described method allows calculation of symmetrical components during transient and under non-sinusoidal conditions. Those components were implemented in relay protection algorithms for identification of internal faults in transformers. Various examples of transformer faults were studied and illustrated.