Condition assessment of transformer oil using UV-Visible spectroscopy

Abstract

Transformer plays an important role in both the transmission and distribution system in electrical power system network. During continuous long period of its operation, transformers are mainly subject to huge thermal and electrical stresses, which can cause the degradation of the insulating oil present inside the transformer. The degradation of such insulation leads to catastrophic failure of transformer which further leads to power system network failure. Since there is a great necessity of inspecting the oil time to time, absorption spectroscopy is considered for condition assessment tool because it has the potential to take measurements during operation, which has better measurement ranges for low concentrations. In this work, a novel method used for transformer health assessment is developed based on the characteristic of spectral absorption by adopting ultraviolet absorption technique. The outcome of the absorption of in-service and laboratory aged transformer oil is so significant that absorption increases by observable margin over a wide range of wavelengths. From the obtained results, the sensitivity and reliability of the UV-Visible method in monitoring degradation of oil is analysed and discussed.

Comparison of Electric and Radiometric Methods for Liquid Dielectric Diagnostic

“…The results are more accurate than the ASTM method, but in addition to determining the degradation -darkening of the sample, it is not possible to determine anything else. Simple spectral measurements in the visible area are most commonly used in the chemical industry and, above all, in the food industry for measuring the quality of used edible oils [1,8,9,10].…”

Comparative study of the degradation rate of new and regenerated mineral oils following electrical stress

“…Their condition and lifespan can be mathematically or experimentally evaluated by the physicochemical, electrical or mechanical characteristics of their insulation system [1, 2]. A large number of power transformers are filled with mineral oils because of their advantages that constitute unique combinations of dielectric, cooling and oxidation stability properties [3].…”

Analysis of transformer oil degradation due to thermal stress using optical spectroscopic techniques

“…Though DGA has been widely accepted method for the past few decades, it has certain drawbacks like it necessities carrier gas, regular calibration, and lack of expert personnel . To overcome these shortcomings with DGA, in this work, optical spectroscopy methods such as ultraviolet‐visible (UV‐Visible) spectrometer and Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) techniques have been proposed and implemented . The test has been conducted on different transformer oil samples, which have undergone thermal stress, using these methods.…”

“…11 To overcome these shortcomings with DGA, in this work, optical spectroscopy methods such as ultraviolet-visible (UV-Visible) spectrometer and Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) techniques have been proposed and implemented. [12][13][14] The test has been conducted on different transformer oil samples, which have undergone thermal stress, using these methods. The UV-visible spectroscopy results indicated the expected degradation level in every sample, whereas, with FTIR spectroscopy, various functional groups existed in the degraded oil are identified.…”