Power Cable review - A technical review on power cable diagnostics methods

Research Project, 2019 – 2022

To answer the questions for achieving an effective cable maintenances, requires a deep understanding and experience from both monitoring and diagnostic methodologies used in the field. A number of techniques have been presented as suitable for determining the performance of cable insulation by both companies and research institutes. Unfortunately, all methodologies have limitations which are often avoided or misinterpreted when they are to be commercialized. An example of this is the often-used technique for determining the loss factor (Tangent delta) in insulation material can today only be measured at a relatively low frequency, whereby properties at higher frequencies cannot be determined. The accuracy of leakage current measurements depends largely on factors determined by the environment and moreover, rapid current transients cannot be measured either. Measurement of partial discharges (PD) can today be measured during operation, but commercial equipment often fails to perform diagnostics at the rapid voltage transients and disturbances that occur when using modern power electronics. In addition, the choice of equipment for diagnostics is often made more based on sales information and advertisements than on meeting the technical requirements set for full function during operation. Today, there is a lack of a thorough overview of the different methodologies that exist, while the knowledge of the technical performance of each method is insufficient to make a correct choice.