Investigation of a Liquid Metal Fault Current Limiter Based on Current Injection Method

A new structure of liquid metal fault current limiter (LMFCL), which can shorten pre-arcing time under short circuit faults significantly, is introduced in this paper. The limiter utilizes a current injection method to strengthen the self-pinch effect in liquid metal, thus responding faster to fault currents in power systems. As we know in the previous literature, a narrow channel in the current path through liquid metal leads to an increase in current density, strengthening the self-pinch effect consequently. Obviously, a channel with smaller cross-sectional area will obtain a higher current density and ignite an arc faster, but the rated current-carrying capacity is also decreased. Compared to existing liquid metal fault current limiters, the proposed one has a shorter pre-arcing time and allows a considerable rated current at the same time. First, the model and operation principles of the new structure are presented. Next, simulations of the current and force distributions in the limiter are carried out. It will help to explain how the self-pinch effect is strengthened, so as to make it easier to ignite an arc. Then, the pre-arcing time behavior and current limiting performance of the proposed structure are tested to validate the idea. Finally, the experimental results are concluded, and future research directions are discussed.