Partial discharge monitoring in medium voltage cables

Of the vast amount of MV cables in the UK, the majority was installed in 1950psilas and 1960psilas. With a design life 60-70 years, age induced degradation and failure of the UK MV systems is becoming increasingly prominent in the minds of plant owners and operators. In this paper, the authors discuss the business case for on-line PD monitoring vs. off-line and compare on-line vs. off-line PD monitoring in MV cables. The paper will also present Wavelet-based denoising techniques as applied to on-line PD test data with examples of analysis and interpretation of practical, in-service data. The effectiveness of the Wavelet-based technique in comparison with other techniques such as the matched filters and the traditional filters will be discussed. Finally challenges for the employment of large amount of PD data for degradation diagnostics purposes will be discussed.