Research on influence of double energy absorptions on dynamic volt-ampere characteristics of metal oxide varistors

Abstract

Metal oxide varistors (MOVs) are extensively employed in DC circuit breakers (DCCBs) to suppress overvoltage, dissipate energy and build up voltage after interruption. Despite their widespread use, the performance of MOVs under short-time, double energy absorption conditions is not well understood, posing a challenge to their application in open-close-open (OCO) operations of DCCBs. In this paper, a MOV double energy absorption test platform is established to investigate the deviation in volt-ampere characteristic. The Fréchet distance is proposed as the criterion for assessing the similarity of MOV dynamic volt-ampere characteristics, and the influencing factors are studied. It is observed that a 15% increase in the absorption of rated energy may result in roughly 20-unit rise in the Fréchet distance. Furthermore, the deviation in volt-ampere characteristics during the second pulse is found to be independent of the time interval, affirming that the OCO operation within 300 ms constitutes an adiabatic process. The excursion of the volt-ampere characteristics is dominated by the energy and remains unaffected by the peak current of the initial pulse. These findings lay the foundation for the subsequent MOV dynamic characteristic balance test and model modification.