Degradation of ZnO based surgearresters under field conditions

An experimental study of the degradation of ZnO based lightning arresters is presented. The study included X-ray, SEM and electrical characterisation of commercial samples, first as received and then after they have been subjected to either an artificial degradation or field degradation. The results show that changes in the specific local composition are clearly associated with the degraded samples, indicating the possible mechanisms for this phenomenon, in terms of segregation of some species during the degradation and also in terms of some of the particular microstructures observed in the laboratory and in the field degraded specimens, which indicates the pertinence of field experiments for exploring the span of the working life of these devices.