THE ENERGY-ABSORPTION CAPABILITY AND TIME-TO-FAILURE OF VARISTORS USED IN STATION-CLASS METAL-OXIDE SURGE ARRESTERS

Varistors for use in station-class surge arresters were tested to dest ruction to determine their energy absorption capability at current lev els ranging from 0.8 A(peak) to 35 kA(peak). Typical mean values incre ased from 400-600 J/cm(3) at the lower current end to 1,600-2,000 J/cm (3) at 35 kA(peak). The product of the mean time-to-failure and the me an current was found to be a constant over five orders of magnitude. T he varistor failure mode was found to be a characteristic of the curre nt magnitude. It is recommended that standard test methods be develope d for the energy absorption capability of metal-oxide surge arresters, and be included in relevant standards.