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Voltage-current characteristics of a diffusion vacuum arc

1981; Elsevier BV; Volume: 104; Issue: 1-2 Linguagem: Inglês

10.1016/0378-4363(81)90042-5

1873-2127

J. Kutzner,

Electrical Fault Detection and Protection

The arc voltage for a low-current vacuum arc between copper electrodes has been measured in dependence on current (in the 50–340 A range), electrode separation (4.5–36 mm) and two anode diameters (11 and 20 mm). The results show that the anode-cathode voltage contains a dc component Uo on which the oscillation component ΔUa is superimposed. It is found that a critical solid angle ωcr subtended by the anode at the cathode center exists which divides the voltage characteristics into two regions. At large solid angle, if ω >ωcr, the magnitude of the Uo component is approximately constant and the voltage fluctuation component has a low amplitude. For ω < ωcr variations of Uo with solid angle have been found and ΔUa exhibits large amplitude fluctuations. The results can be explained on the basis of two criteria representing the mechanism of phenomena in the anode regions, i.e. the critical solid angle and the critical power density on the anode.