Observation of arcing inside a fuse under capacitor-discharge using 1 million frames per second X-ray imaging

Despite their apparent banality, fuses are still obligatory components in modern electrical equipment by offering the ultimate protection against faulty conditions and guaranteeing the disconnection of the damaged legs. Melting of the conducting wire is not as intricate as cancellation of the current by the electrical arc occurring during fuse-operation. Generations of engineers and scientists investigated for understanding complex phenomena related to interaction between arc and sand arranged as energy-absorbent. Most of their observations have been run post mortem. All had the dream to make the actual movie of an arc inside the fuse-envelop. A few of them approached this fantasy by using diverting ways such as spectroscopy through a window or matrix of magnetic sensors. Unfortunately that gave deficient information. For the first time a team from MERSEN, together with researchers from SIMAP-laboratory at the University of Grenoble took profit of the facilities of the ESRF-synchrotron also in Grenoble to proceed to ultra-fast X-ray imaging of the arc inside the envelop. Observations up to 1,000,000 frames per second have been performed. Analysis of the records brings valuable information about the arc in the fuse and allows adjusting models, with a major interest for very fast operation under high di/dt.