Conditon Assessment of Service Aged HV Power Cables

SUMMARY In this contribution experiences made in the Netherlands by joint activities in the field of condition assessment of service aged HV power cables are presented. It is known, that the insulation failures in a cable network may be caused by lower dielectric strength due to aging processes and/or by internal defects in the insulation system. As a result, based on the information provided by non-destructive on-site diagnostics related to insulation degradation, preventive steps can be taken to estimate the actual condition of a service aged cable system. This information is important for service availability and reliability or asset management decisions about maintenance or replacement of a particular cable section. After a survey of all relevant information about the cables in the network, diagnostics are carried out. In particular, to assess the condition of a certain cable type diagnostic packages are developed. Due to application of modern technological solutions in power electronics and signal processing efficient way of on-site diagnostic of HV power cables up to 150kV has been applied for a selected number of HV cable sections. Interpretation is done based on criteria for each diagnostic. To obtain experience norms for maintenance and replacement of a particular power cable, the diagnostic information as obtained using on-site diagnostic measurements are statistically analysed. To support the maintenance and operation decision processes, all results together are used for a classification of the cable section.