Increasing the reliability of MOV arresters

A shunt-gap module is designed for use in metal-oxide surge arresters to increase their tolerance to temporary system overvoltages and to lower the protective response. These are conflicting design objectives in current gapless metal-oxide-varistor (MOV) construction. Both objectives are fulfilled by the module, which, when incorporated into an MOV arrester, provides a 60% reduction in watts loss, a 20% lowering of the protective response, and a dramatic improvement in temporary overvoltage withstand. The module features a single shunt-gap assembly centrally located within two MOV disks. One shunt-gap assembly is incorporated in each 9 kV arrester proration