Application of side-illumination fluorescence measurement technique for monitoring of quality of dielectric fluids

The side-illumination fluorescence spectroscopy was used for early detection of oxidation of the transformer's insulating fluids. Aging of petroleum oil, MIDEL dielectric fluids and their mixtures both in the presence of the catalyst and transformer paper and without them was investigated. A comparison of the obtained optical characteristics of dielectric fluids — fluorescence and transmittance spectrum with the electrical parameters — resistance and tangent of dielectric loss angle were carried out. The explanation of the obtained regularities is given, in particular, the ability to distinguish effects associated with the oxidation of oils from the effects due to the dissolution of moisture and contamination of oil by sludge at the aging process is demonstrated. The possibility of applying the method for measuring the optical attenuation in the dielectric liquids with high transparency is shown.