Simulation Study of Multi-break Current Equalization Characteristics of Vacuum Generator Outlet Circuit Breakers

The existing pumped storage power station generator outlet circuit breakers all use SF6 circuit breakers. The multi-break parallel design of vacuum circuit breakers is an effective way to solve the inadequate rated current of the vacuum interrupter. However, multi-break parallel structures suffer from uneven contact resistance and uneven currents caused by unsynchronous breaking, leading to problems such as interrupter life decay and even opening failure. This paper investigates the multi-break parallel current equalization characteristics of generator outlet circuit breakers and their key influencing factors. Firstly, the design of multiple guide bars in parallel is proposed by analyzing the equalization characteristics of different shapes, lengths and numbers of guide bars as well as considering the contact resistance variation; then a multi-physics field model based on the finite element method for multi-break vacuum circuit breakers was established, considering the static mean flow characteristics under the initial and multiple opening deviations, and analyzing the effect of skin effect on the current distribution in the guide rod section; finally, the equalization characteristics of the flow in the dynamic case when the gates are not synchronous are considered. The simulation results show that the use of long guide rods can achieve a good equalization effect, the skin effect does not have a significant impact on the uniform distribution of the current of a single guide rod, and the maximum current deviation between the guide rods is 3.4%.