Influence of Phase-Angle Jump on Inrush Currents of Transformers

In power systems, the transients caused by the energization of the power transformers and the voltage sags are some of the more common problems. The voltage recovery after voltage sag can saturate the transformer and this saturation can produce an inrush current, which is similar to that of the energizing. In this paper transformer inrush currents resulting from voltage sags with and without phase jumps are experimentally analyzed. The analysis of the test results reveal that the peak value of the inrush current strictly depends on the phase jumps which are occurred during the voltage sags