DEGRADATION OF ZNO BASED SURGE ARRESTERS UNDER FIELD CONDITIONS

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