Substation monitoring by acoustic emission techniques

The deterioration of oil-paper insulation in high voltage equipment is a ma tter of continuous concern. The degradation typically occurs under normal o perating conditions although insulation failure may be accelerated under ce rtain in-service conditions, such as snitching and lightning Impulses, over voltages and moisture ingress. For this reason, only continuous monitoring can provide the necessary field data to better understand in-service insula tion behaviour, particularly insulation degradation, thus preventing catast rophic damage to property and risk to human life. Based on the promising re sults obtained previously from an acoustic emission (AE) portable detection system an AE substation monitoring system has been developed. This has bee n operational in a 33kV primary substation for eighteen months and detailed data have been collected and downloaded to a computer from a remote site o n a daily basis, The analysed results have indicated that a specific cable box in the substation is a source of heavy discharge activity and a recomme ndation has been made to the Regional Electricity Company that a high-volta ge test be carried out on the suspected switchgear for further investigatio n.