| 摘要 |
<p>A vacuum switching device comprises an evacuated envelope having an insulator; a fixed electrode and a moving electrode which engage and disengage mechanically to perform switching and which include a contact of the axial field type comprising a coil assembly behind a contact disc. The coil assembly has between one and five arms which follow a curved path from a centre electrode to the outer diameter of the contact disc. The curved arms may be formed of successive circular arcs, be of constant width and have a constant separation from their neighbours. The coil can have two, three or four arms whose spiral path covers between 200, 130, 100 and 80 degrees of rotation respectively. The coil assembly can have radiused corners and edges to improve the voltage performance. The coil provides self-generated axial magnetic fields in the axis of the contact gap in order to make an arc diffuse over the contact surface at high currents.</p> |
