Chemometric evaluation of synchronous scan fluorescence spectroscopy for the determination of regulatory conformance and usage history of insulation oils

This paper describes the evaluation of synchronous scan fluorescence spectr oscopy as a means of determining key characteristics of mineral insulating oils that are used in electrical apparatus around the world. Characteristic s of interest to commercial operators include regulatory conformance, the h istory of the oil (whether it has been used or not), and, ideally, the iden tity and manufacturer of the oil. The oils analyzed in this study are highl y relevant to real applications as they were acquired from actual high volt age power transformers operated in the United Kingdom (UK) or from stocks i ntended for future use in transformers. A small number of foreign oils that do not conform to UK regulations were also analysed. Principal components analysis (PCA) is used to evaluate the usefulness of the information contai ned in the acquired fluorescence spectra. This reveals that oils from diffe rent manufacturers can exhibit different types of spectra and that it may b e possible to determine the identity of an oil from its spectral characteri stics. It is also found that the spectra can be used to determine whether o r not an oil has been used and whether it meets British regulatory standard s. It is concluded that synchronous scanning fluorescence spectroscopy, com bined with appropriate chemometrics, could provide the basis for a rapid sc reening test, capable of indicating whether or not a particular new or used transformer oil is suitable for initial use or continued use in high volta ge equipment.