Development of a new surge arrester technology

The authors discuss development of a new arrester that incorporates a resistance-graded series gap with MOV discs which offers several improvements over silicon carbide and gapless MOV arrester designs. The design allows the utility specifiers to substantially improve surge protection to distribution equipment, especially URD cable and overhead distribution transformers. It provides substantial improvements in temporary overvoltage withstand capabilities, which improves arrester reliability. The increased temporary overvoltage capability allows users to protect ungrounded wye-delta transformer banks without sacrificing surge protection. The unique sharing of voltage between the disc and ring/gap sections improves durability during high-current discharge testing. The ring/gap sections´ overvoltage capability and the lower stress present across the MOV discs themselves under steady-rate conditions result in a reduced likelihood of initial energisation failures, which is a major concern to utility operating personnel