Influence of Parallel Inductance-Capacitance Branches on Current Commutation Characteristics of Air Arcs

To address the technical challenge of interrupting fault currents in direct current (DC) power systems, a DC interruption scheme based on the magnetic control oscillation characteristics of air arcs is proposed. Applying an external transverse magnetic field to the air are within a narrow gap enables the arc voltage to oscillate periodically, thereby creating a negative damping oscillating current between the arc and the inductor-capacitor (LC) branch. This facilitates fault current transfer, ultimately achieving current interruption. Experimental studies are conducted on the current transfer process at the resonant frequencies of four parallel LC branches, and the effect of the transfer branch capacitance on the peak transfer current is analyzed for main circuit currents ranging from 5 kA to 13 kA. The results indicate that increasing the resonant frequency of the LC branch at a 5 kA main circuit current can shorten the current transfer time to 0.84 ms. However, as the main circuit current increases, the resonant frequency of the LC branch needs to be adjusted to match the oscillation frequency of the arc to create a zero-crossing of the arc current. Increasing the capacitance of the transfer branch effectively enhances the initial peak transfer current, thereby boosting the current transfer capability. Additionally, the attenuation of the magnetic field during the current transfer process leads to a decreased rate of rise in arc voltage, affecting the continuity of the resonant current's negative damping oscillation. This study validates the feasibility of the air are magnetic control oscillation-based DC interruption scheme, providing a new approach for the design of economical DC circuit breakers.