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 kA ∼ 100 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.