Interpretation of dielectric loss data on service aged polyethylene based power cable systems using VLF test methods

摘要

In the past, cable system management has proceeded on the basis of cable system age, assuming that the oldest has the lowest reliability. It is now recognized that this constitutes a very coarse assessment and that a more targeted approach would bring a more efficient use of resources. The more targeted approach requires an assessment of the health of cable systems. It is increasingly common for the assessment of aged cable systems to be made through the application of diagnostic measurements. A recent study has shown that Very Low Frequency (VLF) Tan ;4; is the most commonly deployed cable system diagnostic. The practical use of this technique has been supported by the international standards IEEE Std. 400-2001 and IEEE Std. 400.2-2004. A key part of these standards is the guidance provided to a user that is detailed in the "Figures of Merit". These enable users to make practical improvements to the cable system as they help to identify cable systems that are more likely to fail in service in the near future. To aid these decisions a series of criteria have been developed. The benefit of the criteria described here is that the process for their determination is rational, reproducible, and transparent. The outcomes are supported by a probabilistic assessment of service performance.