抄録
A self extinguishing principle of GCB without puffer action (“Autopuffer GCB”) using an external magnetic field was investigated for improvement of the interrupting capability in the small current region (several kA). Properties of the rotating speed of an arc, the arc voltage and gas pressure rise in an expansion space under the external magnetic field were studied experimentally. The relation between the interrupting capability and the radial magnetic flux density in the “Autopuffer GCB” with a permanent magnet (“Magnet-assisted autopuffer GCB”) was obtained experimentally and also analyzed numerically. The results are summarized as follows,
(1) The arc column is driven in the azimuthal direction by the radial component of the external magnetic field.
(2) The rotating speed of the arc driven by the radial magnetic field of a permanent magnet remains constant in the arc current range below several kA, while it decreases with an increasing current in the current above several kA.
(3) Since the arc rotation raises the arc voltage and gas pressure in the expansion space, the gas flow from the expansion space to the arc increases at around current zero, then the interrupting capability is improved in the small current region.
(4) It is confirmed that the “Magnet-assisted autopuffer GCB” has a good interrupting capability not only for the large current region but also the small current region.
