Study on the On-Line Insulation Monitoring Technique for Transformer Oil

Dissolved gas analysis (DGA) is technique to relate the transformer fault with the gases dissolved in the insulating oil of oil-immersed transformer, which can be used to analyze some of the faults inside the transformer. The on-line DGA system designed in this article adopts the polymer film to extract the gases dissolved in oil, uses the gas sensors to detect the gas concentrations and the optical fibers to transmit the gas concentration information to the IPC in the control room. The system has been installed for more than one month, and the measurement results have shown that the maxim error of the method in gas concentration detection is 11% compared with the off-line chromatography. The method presented in this article is succeeding in improving the security situation of the transformer in operation at a low cost.