Direct detection of acetylene dissolved in transformer oil using spectral absorption

Dissolved gas analysis (DGA) is an effective method to indicate the health status of power transformers as miscellaneous dissolved gases are often related to the degradation of insulation materials and inner electrical faults. To realize real-time and accurate measurement of dissolved gas, direct infrared spectral absorption focusing on acetylene detection without an oil-gas separation process is proposed in this study. Based on Fourier transform infrared spectroscopy (FTIR), the infrared light transmission of transformer oil is explored, and spectral absorption parameter of acetylene in gas state and oil phase is compared and analyzed. In the laboratory, the sensitivity of direct acetylene dissolved in oil is tested and enhanced. It is confirmed that the transformer oil can transmit the infrared light, locating in the near infrared spectrum of 0.800-1.687 μm and 1.770-2.261 μm. It is also proved that the direct infrared absorption method can detect acetylene dissolved in oil at the central wavelength of 1.534 μm, laying the basis for new type of DGA technique without oil-gas separation.