PERFORMANCE OF PARALLEL SURGE ARRESTERS

Abstract

The operation of parallel surge arresters can improve energy absorption capability if the arresters are   similar and are installed close to each other. However, it has been reported that any small difference in   the individual V-I characteristics can lead to unbalance in current sharing. When the arresters are   installed some distance away from each other, travelling wave effects can modify the effectiveness of   parallel arresters for surge overvoltage protection and, in this case, detailed simulations are required to   ascertain the level of protection. Such a situation occurs in practice with large substations or short   underground cable connections. Various studies have shown that a requirement for two-arrester   protection is closely dependent upon the type and length of cable used.   In the case of overhead lines, the distances are much bigger and the main objective of line arresters is   to reduce the flashover rates due to surge overvoltages. This is especially relevant to lines located in   regions of high lightning activity, lines with compact/uprated design where the phase-to-phase and   phase-to-earth air clearances are reduced.   In this paper, we present a study of parallel arresters considering the separation distance and their   application to overhead lines. Various scenarios of overhead line configurations were considered and   the overvoltage levels were calculated for each case. Assessment of flashover performance is also   conducted for a number of conditions. A number of calculation techniques were used and compared.