Effect of thermal ageing on the fluorescence characteristics of mineral transformer oil for EMU

Abstract

Detecting oil leakage faults in traction transformers is critical to Electrical Multiple Unit (EMU) operation fault detection. Mineral transformer oil, which exhibits fluorescence characteristics, is commonly employed in EMU traction transformers. The position and intensity of the fluorescence characteristic peaks determine the selection of excitation light source wavelength and imaging spectral band for the mineral transformer oil leakage detection technology based on fluorescence imaging. However, the fluorescence characteristics will change with ageing. To investigate the changes in the fluorescence characteristics of mineral transformer oil used in EMU during the ageing process, accelerated thermal ageing experiments were conducted in the laboratory. The three-dimensional fluorescence spectra of samples were collected regularly. Furthermore, the hydrocarbon group composition and interfacial tension of the samples were routinely detected, with the intent of unraveling the underlying factors contributing to the variations observed in the fluorescence spectra. The results show that the position of the fluorescence spectrum peak gradually shifts to the long-wave direction with the prolongation of the ageing time, and the intensity of the peak continuously decreases. The experimental results offer the experimental and data foundation for the selection of excitation light source wavelength and imaging spectral band in the application of fluorescence imaging detection technology to detect oil leakage faults in mineral transformers of EMU.