Investigation on Transformer Inrush Current Switched by Controlled Vacuum Circuit Breaker

When the no-load transformer is energized with the vacuum circuit breaker (VCB), the magnetizing inrush current with large amplitude will be generated due to the saturation of the core flux, which endangers the safety of the power system. The influence of the operating time scatters of VCB on the inrush current suppression is analyzed. The principle of VCB closing resistor to suppress inrush current is expounded. The combination of VCB closing resistor and controlled switching technology is proposed, which maximizes the effect of inrush current suppression. The influence of different factors on the inrush current is simulated by EMTP/ATP to obtain the best scheme to suppress the inrush current. At last, the accuracy of the controlled method is verified by the experiments. The results have guiding significance for restraining the inrush current during no-load transformer switching.