1 Modelling of Restriking and Reignition Phenomena in Three-phase Capacitor and Shunt Reactor Switching

Capacitor banks and shunt reactors are frequently switched by circuit-breakers in medium voltage (MV) and high voltage (HV) electricity networks. In recent years there have been explosive failures due to circuit-breaker restriking and reignition consequently there is a need for monitoring techniques that will facilitate the identification and quantification of the onset of more severe restriking. Whilst there has been detailed analyses of single-phase shunt reactor and capacitor bank switching there is a paucity of information about restriking phenomena and reignition in three-phase circuits for the correlation of system problems with specific waveform characteristics to develop the necessary identification algorithms for proactive monitoring of circuit-breakers ’ condition. This paper describes the modelling restriking and reignition occurring during three-phase capacitor bank and shunt reactor switching using the Alternative Transients Program (ATP) and network data from AS 4372-1996. Information from the ATP models and data resulting from the simulations are examined with a view to developing an intelligent diagnostic system with logging and alarm features. This modelling method can be easily applied with different data from the different dielectric curves, circuit breakers and networks. 1