Modelling of Arcing Phenomena During Opening Contacts in Novel Circuit Breakers

Abstract

The increasing adoption of renewable energy and DC-based loads has renewed interest in DC transmission systems. Unlike AC networks, DC systems lack natural current zero-crossings and exhibit rapid fault propagation, making interruption highly challenging. Reliable and scalable DC protection is essential for future power systems, with mechanical DC circuit breakers providing the most cost-effective approach to managing DC faults. Maximising their performance depends on accurate prediction of arc behaviour.

This study primarily focuses on compact LC commutator-based DC circuit breakers operating at voltage levels between 1–5 kV. The research investigates the reignition phenomenon observed after current commutation and reveals that the key factor governing reignition is the temperature of the boundary layer between the arc plasma and the electrode surface. Conventional breakdown models, such as Paschen’s law and streamer theory, are inadequate for describing reignition because they assume uniform gas temperature at room conditions. In reality, the air temperature within the contact gap varies non-uniformly as the electrodes separate. To address this limitation, a hybrid breakdown voltage model was developed based on non-uniform temperature distribution and dynamically changing electrode gap. The model covers the full temperature range of 300–5000 K and quantitatively reproduces published experimental data with a prediction error within 20%. The analysis also provides a physical interpretation for the transition between the Townsend and streamer breakdown mechanisms. The applicability of the arc model is further examined in low-voltage DC switches (< 100 V, typical for electric traction systems). By simulating the influence of external electric field and electrode opening velocity on the arc behaviour across different stages, the model predicts arc extinction time within ±15% accuracy under multiple experimental conditions.

Overall, this work provides a unified modelling framework that bridges the gap between fundamental arc physics and practical circuit breaker design. The developed model offers predictive capability for evaluating the influence of different parameters on arc extinction performance. These findings contribute physical insight into arc dynamics and establish design guidelines for optimising compact DC interrupters across different voltage ranges. The modelling approach can be extended to higher-voltage systems to support future DC protection technologies.

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