Analysis of AMF vacuum contacts with ferromagnetic material

It is well known that vacuum interrupters with axial magnetic fields (AMF) have higher interrupting capability. But as the interrupting current increases to some extent the vacuum arc still begins to constrict even uniform AMF is applied. From the authors´ previous research work, the high current vacuum arc could distribute more evenly on contact surface under nonuniform distribution AMF produced by means of introducing ferromagnetic material (iron) with certain shape to electrodes. The main work of this paper is to analyze the distribution of AMF in the interelectrode gap after introducing the ferromagnetic material with finite element method (FEM).