Development of advanced arresters for GIS with new zinc-oxide elements

New zinc-oxide elements with a varistor voltage about twice that of conventional ones of the same thickness have been developed by reducing the ZnO grain size with a new additive, which enable to halve the series number of elements in metal oxide surge arresters. The advanced arresters with these elements for GIs are compact by 40 to 60 % in volume compared with conventional ones. The electrical and mechanical performance of the advanced arresters was satisfactory through the various evaluation tests such as thermal stability test, residual voltage test, seismic test, long-term stability test, etc.