A “Resonance” Method to Decrease Electrode Erosion in Magnetically Rotated Arcs

摘要

In many industrial applications of high-current arcs with tubular or ring electrodes, the arc electrode attachments are forced to rotate in order to reduce electrode erosion. A method intended to further reduce electrode erosion is suggested. This goal is achieved by forcing the attachment to drift in the axial direction. The axial arc motion results from the Lorentz force experienced by a radial arc under the influence of an azimuthal magnetic field. This magnetic field could be created by a cable located outside the electrode. It is shown that if the current in the outside cable oscillates with a frequency close to the frequency of the arc rotation, it leads to a continuous arc axial drift. The effect has a resonance characteristic: even a low ac current in the cable causes the arc drift. As a result of the combination of fast arc rotation with a relatively slow axial drift (reversed from time to time), the arc attachment moves within a band of a controllable width. The spread of the electrode heat load over a wider electrode area reduces electrode erosion. Sources of the azimuthal magnetic field other than a cable are suggested.