Analysis of electrode for vacuum interrupters with nonuniform axial magnetic field

The authors have researched experimentally that vacuums under a nonuniformly distributed axial magnetic field (AMF) can keep a diffuse mode at a relatively high current, so that the interrupting capability of vacuum circuit breakers can be increased. The radial distribution of AMF is changed by means of introducing ferromagnetic material (iron) with a certain shape to the electrodes. In this paper, the distribution of AMF generated by electrodes with ferromagnetic material is computed by the finite element method (FEM). The influence of eddy current after introducing ferromagnetic material is taken into account. Furthermore, a type of commercial vacuum electrode with nonuniformly distributed AMF is also analyzed.