Application of statistical tools for assessing service availability of high voltage power cables

The practical interest of power utilities regarding the maintenance and replacement policy of insulating systems such as cables, switchgear and transformers is often based on experiences knowledge and data from the past. The ages of components in the network are increasing and this can result in an increase of the number of failures in coming years. To be able to monitor the components powerful tools are diagnostic measurements performed on the network components and analysis of life time data obtained from the exploitation of the components. In this contribution the analysis procedure is applied to life time data of 50 kV mass-insulated cables of a Dutch utility.To see what can be expected in the future the population in service together with the obtained failure rate curve is used. This gives statistical information regarding expected failures and critical connections. The analysis can help the asset manager to determine if immediate action has to be taken to meet the business policy e.g. condition assessment, maintenance or replacement, or if the current policy fulfils the conditions.