Comment on on-line monitoring techniques for dissolved gas in transformer oil

On-line monitoring of dissolved gas in oil is one of effective methods of estimating the running states of transformers. This paper generalizes the conventional method of on-line monitoring of dissolved gas in transformer oil, and reviews the application and current situation of on-line monitoring techniques for dissolved gas in transformer oil in the aspects of oil-gas separation and on-line gas detection. By comparing several oil-gas separation techniques, permeable membranes are thought to be with high cost performance and be more fit for on-line monitoring of dissolved gas in transformer oil. By analyzing the principles and the characteristics of current on-line detection techniques of gas, the shortcomings of chromatographic columns and gas sensors are regarded as consuming gas, poor long-term stability, cross-sensitivity, et al. Compared with Fourier infrared spectrometry, photoacoustic spectrometry has some advantages such as small gas demand and high sensitivity, which makes it suit to be used in on-l