Gas evolving materials for improved low current interruption in high voltage current limiting fuses

Various organic and inorganic compounds have been identified to be very effective arc interrupters when applied to the silver elements of high power current limiting fuses (typical ratings for a single barrel range from 5.5 - 15.5 kV, 20 - 250 Amps). These compounds reduced the non-interruption band which occurs between the rated fuse current and the minimum interruption current. The lower current limit at which the fuse can interrupt is directly affected by the gases evolved during arcing. These new compounds generate gases and free radicals which assist in deionizing the arc by a combination of the gas species evolved, increased local pressure, and by not forming any carbon residues. These novel compounds and binders significantly improved the interruption capability of high power fuses at low current levels. Compounds, test methods, evaluation, actual short circuit tests in a high power lab, and theoretical analysis are described.