Research on technology of dissolved gas analysis in oil based on T-type resonant photoacoustic cell

Aiming at the need of detecting trace dissolved characteristic gases in transformer oil, technology of dissolved gas analysis (DGA) in oil based on a T-type photoacoustic (PA) cell with a small capacity was proposed. The capacity of the T-type PA cell was reduced to 30 mL by optimizing the parameters. This resulted in a significant reduction in sampling volume of transformer oil. A laser photoacoustic spectroscopy (PAS) system for DGA in oil was built combined with headspace degassing method. The T-type resonant PA cell was used to enhance PA signals. The second-harmonic wavelength modulation spectroscopy (2f-WMS) technology was used for detection of escaped gases. The experimental results show that the detection limit of acetylene (C2H2) gas dissolved in oil is 0.5 μL/L when the oil volume is 50 mL. The technical scheme has the advantages of small oil extraction volume, high precision and fast response speed.