The use of spectroscopy with chemometrics to assess the condition and predict the lifetime of paper and oil used as transformer insulation

Large power transformers consist of copper windings wound with Kraft paper (cellulose), and the entire assembly is immersed in mineral oil. Under load, the system ages, primarily from thermal effects and ingress of atmosphere, causing progressive degradation of both the paper and the oil. This can potentially lead to catastrophic failure of the transformer. Hence, condition monitoring and failure prediction of these transformers is vital. Currently, monitoring the degradation directly is a laborious process and can only be performed ex-situ through oil and paper sampling which for the paper is also destructive. The use of spectroscopy coupled to chemometrics points to a new, potentially rapid and very precise route for condition assessment of transformer paper and oil.