Sergio Meregalli*, Giuseppe Rizzi*, Stefano Fratti**, Salvatore Pugliese** POWERGRID Europe, Milano 3-5 Giugno 2008 *CESI RICERCA **AEM Distribuzione Milano In Europe, many components of the electrical assets are reaching the end of their design life time without any significant increase of the failure rate. Asset Managers have therefore the necessity to decide upon the end of life management in term of life extension or replacement of the components. As a matter of fact the systematic replacement of the components having reached their project life time is not an option; it is important to establish a priority list on the base of real ageing of the component. For the most expensive and strategic components a maintenance program and an historical data base containing test results, failures and loads is normally available and can be used as a base to implement the renewal strategy. On the other hand such a complete data set is not available for less strategic components (e.g. medium voltage cables), often representing very numerous population. The paper discusses the approach jointly designed by CESI RICERCA and AEM Milano for the assessment of the ageing degree of MV power cable. It basically consists in two group of tests to be carried out on-site and in laboratory on samples of cables representative of an homogeneous family in term of service age and load. On site tests mainly devoted to the identification of localised defects (accessories quality) are based on the measurement of PD activity by means of the off-line techniques. Moreover, tests for the assessment of the mean degradation of cable insulation are carried out by means of the measurement of integral quantities as for example loss angle value. On the base of the results, few samples of cable are removed and tested in laboratory for a deeper analysis of the ageing of the insulation by means of modern techniques like the measurement of polarisation and depolarisation current (PDC) the values of loss angle at different frequencies (FDS) and the breakdown voltage.