This paper investigates the effect of different three-phase transformer configurations in single power source. New
investigating simulation models for single power source are presented. The models of transformer configuration for each
side (primary and secondary) used were Y (wye), Yn (wye-grounded) and ∆ (delta). The effect of ground fault is
determined by generating station arrangements and transformer configurations. The simulation of single power source showed the performance generator within the SLG fault at various three-phase transformer configurations. Simulation was conducted in PSCAD/EMTDC 4.2.0 and the results were analyzed, presenting comparison of the fault impact at different three-phase transformer configurations. It was clearly shown that the SLG fault current at the single power source was highly dependent upon the type of the three-phase transformer configurations used during the ground fault at the secondary side of the transformer