Metal oxide surge arresters in AC systems

The development of the zinc oxide varistors to be applicable to the protection of transient overvoltages in HV systems, introduced an equipment with qualities very much different from the qualities of the up to then well known surge arresters with silicon carbide resistors and series spark gaps. The correct application of this new type of surge arrester needed more detailed knowledge about the transient behaviour of the system and the arrester stresses caused by the system during different operating conditions.