Distributed acoustic/vibration sensing: Towards advanced transformer condition monitoring

A novel method for transformer vibration monitoring using intensity-based distributed acoustic/vibration sensing (DAS/DVS) is presented. Fibre optic sensors were fully integrated into an oil-filled medium voltage distribution transformer. Open-circuit in-situ measurements were carried out using a single and three-phase supply with an electrical power of up to 30 kVA. Spectral analysis of the mechanical vibrations were performed by measuring the frequency response of the transformer using plain fibre-and transducer-based DVS approaches. The results were compared with the spectra of a microphone mounted on the outside of the transformer housing and the electrical measurements on the high voltage side. Using the fibre optic DVS based monitoring we were able to detect changes in operating power and frequency. Further it could be shown, that it is possible to identify anomalous behaviour such as electrical/mechanical noise sources using the determined vibration spectra.