Unstable behavior of parallel fuses as an opening switch

When fuses are used as a pulsed power opening switch, several are often connected in parallel to treat large energies. The waveforms of total current flowing through parallel fuses and of the output voltage could not be distinguished from those in the case of a single fuse, and therefore the currents flowing through each fuse have not been observed in detail. As a result, the actual behavior of parallel fuses, like the interaction between fuses, are not well known. Here, an experiment using two fuses is carried out to understand the behavior of parallel fuses clearly. The waveforms of current flowing through each fuse are different. Unstable behaviors, in which the difference of currents flowing into two fuses increases, are observed, and the condition and probability of appearance of the unstable behavior are discussed. The cause of unstable behavior is that the changing rate of fuse-resistivity on input energy is different in each state of wire. The difference of an initial dimension of parallel fuses or a kind of disturbance during the fuse action could immediately trigger off the unstable behavior. The difficulty in predicting the behavior of parallel fuses is explained.