Post-arc current in low-voltage vacuum circuit breaker: Measurements and physical peculiarities

This paper presents the main peculiarities of the post-arc (p.a.) current within the low-voltage switching process in a vacuum as compared with the medium-voltage p.a. current. The high-frequency p.a. current oscillation is measured and mathematically described. There are two high-frequency components produced by the equivalent scheme of the circuit breaker and by the nonlinear characteristic of the p.a. residual plasma. Also described is the influence of the axial magnetic field (AMF) on the p.a. current evolution and high-frequency oscillation. The authors have noticed that the nonlinear p.a. high-frequency component, produced by nonlinear characteristic of residual plasma, is severely damped by the AMF. Using an analytical approach of the phenomenon, this study also provides a general mathematical model for the p.a. current. The results of the mathematical model contribute to a better understanding of the physical peculiarities of the short-circuit current zero zone.