Berlin 2014 – scientific programme

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P: Fachverband Plasmaphysik

P 3: Plasma Technology I

P 3.5: Talk

Monday, March 17, 2014, 15:30–15:45, SPA HS201

Diagnostics of high-current vacuum arcs for simple electrode geometries — •Kristoffer Ole Menzel, Lukas Hofstetter, Romeo Bianchetti, and Thierry Delachaux — ABB Switzerland Ltd, Corporate Research Center, 5405 Baden-Dättwil, Switzerland

Vacuum interrupers (VI) represent the state-of-the-art technology for high-current interruption at medium AC-voltages of 1kV-36kV. While breaking the current a vacuum arc is ignited between the contacts of the VI. The arc is sustained by copper vapor from the hot electrodes. Due to the pinch effect the arc will appear in a constricted mode for currents above 10kA-15kA resulting in a high thermal load on the VI contacts. To successfully break these high currents, the electrodes are often designed such that an additional transverse magnetic field (TMF) is generated, which induces a motion of the arc. A detailed understanding of the underlying mechanisms of these constricted arcs is of great interest to increase the performance of the VIs. Therefore, in this contribution, measurements of the main characteristics of constricted arcs are presented. In order to allow for an easy diagnostical approach the experiments were conducted for simplified electrode geometries. Besides using high-speed camera videos and arc voltage measurements the high-density copper plasmas were investigated using optical emission spectroscopy. The resulting spectra allow to determine temperature and pressure evolutions when compared with results from FEM simulations. The appearence of Cu(III) lines hints at plasma temperatures above 3eV.