Dynamic Current-sharing of Vacuum Multi-breakers in Parallel based on the Arc volt-ampere characteristic

The generator circuit breaker (GCB) is the key power switchgear for power plants. The rated current and short-circuit current of high-voltage and large-capacity GCBs exceed the capacity limit of a single vacuum interrupter (VI), and multiple VI in parallel can improve the through-current capacity. The volt-ampere characteristic of vacuum arc is the key factor of dynamic current-sharing. Firstly, arcing experiments were carried out in the detachable vacuum chamber (VC) equipped with cup-shaped axial magnetic field (AMF) contacts, and the morphology of the are was synchronously captured with a high-speed camera. The range of peak current was $20 \mathrm{kA} \sim 100 \mathrm{kA}$. Next, the arcing process was divided into the transient stage and stable stage according to the arc voltage and arc morphology, and the law of synergistic evolution of the volt-ampere characteristic and arc morphology in each arcing stage was analyzed comparatively. It is found that the vacuum arc has positive volt-ampere characteristic and synchronization, which will make it possible to realize automatic current-sharing in parallel VIs. Finally, large-capacity dynamic current-sharing experiments with double VIs in parallel were carried out, and current transfer and dynamic current-sharing could be observed. This paper will lay the foundation for improving the opening performance of the high-voltage and large-capacity GCB.