纵向磁场下中频真空电弧的重燃现象分析

Intermediate frequency (IF, 360-800Hz) power supply system has been widely used in more-electric aircrafts. The IF current interruption ability decreases from 22.4kA/360Hz to 14.0kA/850Hz according to the experimental results. In this paper, post-arc re-ignition of IF vacuum arc in axial magnetic field (AMF) is studied. By the solution of the Mayr arc model, the decay time of arc energy is prolonged when re-ignition happens, which goes against current interruption. With the increase of frequency, a small current will cause the change rate of current di/dt to reach the threshold at the time of zero-crossing. In addition, the eddy effect is enhanced, resulting in the increase of the residual magnetic induction intensity and hysteresis phase of AMF. It is found that the re-ignition position in IF vacuum arc always appears first at the margin of contacts. As shown by ANSYS calculation, the electric field at the margin is stronger and the current density is higher, thereby increasing the probability of field emission. By analyzing the arc images, the velocity of metal particles is about 10~20m/s and the dissipation time of the metal particles is longer than the arc time, which may cause the IF vacuum arc re-ignition.