Transition Process of Vacuum Arc to Diffusion Stage Under Transverse Magnetic Field

The transverse magnetic field (TMF) contact structure can generate a magnetic field perpendicular to the arc current flow direction to drive the vacuum arc to move on the contact surface, prevent local overheating of the contact surface and severe melting. Thereby improving the breaking capacity of the vacuum interrupter. The TMF contact has the advantages of simple structure, short current path and low cost. The motion of the arc between the TMF contacts will gradually decrease as the current drops, and eventually the arc will transit to a diffused arc before zero crossing. In this paper, the transition process from movement stage to diffusion stage was experimentally investigated. The arc appearances was analyzed. It was found that the transition process from movement stage to diffusion stage can be divided into three types: slow transition, fast transition and unstable transition.