Transmittance spectra of oxidized insulation oil using terahertz spectroscopy

Abstract

The number of aged power equipment increases and it is important to clarify the characteristics of deteriorated insulating oil. This paper describes the basic study on transmittance spectra of oxidized insulating oils by terahertz spectroscopy. First, the mineral and mixture insulating oils heated in oxygen were measured and observed spectra change. Second, the oxidation process of insulating oil was modeled by using various compositions of dodecane and 2-octanol. The absorption related to hydroxyl groups (-OH) was significantly observed between 6 and 7 THz. And hydrogen bonds were observed from vibration change of OH. The absorption band was also observed in accelerated aging insulating oils used in power equipments as insulating oil.

Industrial Applications of Terahertz Sensing: State of Play

“…Employing THz sensing to detect oxidation products—carbonyl and hydroxyl compounds—in oils is an effective technique, because those compounds are strongly polar and therefore strongly THz absorbing, allowing detection at low concentrations. A number of studies have been performed demonstrating high sensitivity and good discrimination of such measurements (Figure 22) [159,160,161,162,163,164,165]. Contamination by water can also be a cause of oil degradation, especially in engine oils where water is a product of fuel burning, and where sensitive THz detection has been demonstrated [165,166].…”