Rapid online detection of dissolved acetylene in transformer oil by photoacoustic spectroscopy and membrane degassing

Acetylene is one of the main fault gases for oil transformers. The rapid and highly sensitive detection of dissolved acetylene in the insulating oil plays an extremely important role in the diagnosis of transformer faults, as it is produced by the decomposition of hydrocarbons due to discharge and overheating. This work describes a rapid real-time online monitoring system for dissolved acetylene in oil, which integrates a highly efficient Teflon-AF2400/ceramic composite degassing module and a high-sensitive laser photoacoustic detector. Real-time online monitoring is feasible as the detection period of the device is as short as 1.5 min, and the equilibrium concentration of acetylene in the oil can be accurately determined from test data at a degassing time of 15 min. When the concentration of acetylene in the oil changes suddenly, the device can report more than 90% of the change within 30 min. The detection accuracy is improved from 0.9 to 0.3 μL L⁻¹ after corrections are made to account for the influence of temperature on the oil–gas separation membrane.