A new contact design based on a quadrupolar axial magnetic field and its characteristics

Axial magnetic field (AMF) contacts are applied within vacuum interupters e specially in case of high short-circuit current. In this paper a new AMF co ntact design based on a quadrupolar field arrangement and its characteristi cs ar-e presented. In the first part the basic principle of the new contact design is introduced. This is followed by three-dimensional field simulati ons performed with the aid of a Finite-Element-program. The magnitude of th e axial magnetic flux density, the phase-shift between current and magnetic flux density, and the current flow within the contact plate are investigat ed during arcing. The impact of quadrupolar AMF on the arc behaviour during the high current phase is analysed by high-speed films and pictures of the contact surface after arcing. The interruption performance of the principl e has been validated by short-circuit tests up to 12 kV/63 kA.