Estimation of the plasma’s particle densities during the arcing period of a high-voltage fuse

We report in this paper the results of the estimated number densities for the plasma species during the arcing period in a model sand-filled high-voltage fuse. The model fuse was energized at 6 kV, using synthetic test circuit, and a prospective current of 1.25 kA, 50 Hz, was passed through it. The arcing period has been investigated using spectroscopic means. The fuse arc is supposed to be composed of O I, O II, Si I, Si II and Si III particles. Using the estimated values of electron density and temperature, and assuming the plasma to be in Local Thermodynamic Equilibrium (LTE), Saha's and Brunner equations are applied to determine the particle densities of ionized and neutral particles in the plasma. The model high-breaking capacity high-voltage fuse, under the given testing conditions, shows that its arc remains highly ionised throughout the arcing period.