A novel method of measuring transformer oil interfacial tension using UV-Vis spectroscopy

Reliable monitoring and diagnostic techniques for detecting transformer incipient faults are required to help in avoiding catastrophic failures, and to inform an efficient predictive maintenance program, which improves the reliability of the equipment [1], [2]. The overall health of an operating transformer depends largely on the condition of its insulation system [3]. Long-term degradation of an insulation system occurs mainly through heating (pyrolysis), moisture ingress (hydrolysis), and air ingress (oxidation) [4], [5]. Incipient faults within a transformer can be detected by analyzing samples of its insulating oil, e.g., using dissolved gas analysis and furan analysis [6]-[8]. Interfacial tension (IFT) and acid number measurements may also be used to examine the oil quality [9]. Although polar compounds in transformer oil usually have little or no acidity, they can react to form acids, which increases the rate of insulation paper aging. IFT and acid number measurements can therefore provide early warning of such aging [10].