Acoustic detection of partial discharges using non-intrusive optical fibre sensors [current transformers]

Conventional current transformers (CTs) normally have oil-paper insulation and a porcelain insulator in their construction. The degradation process of the oil-paper insulation gives rise to localised partial discharges (PD) within the apparatus. Therefore, on-site PD measurement is an efficient tool to detect insulation problems at an early stage. Fibre optic sensors allow continuous, on-line insulation condition monitoring and have a number of potential advantages over other sensors because of their immunity to electromagnetic interference. This paper discusses PD detection using an optical fibre sensor mounted externally on a current transformer.