Dissolved Gas Analysis in Transformer Condition Monitoring
Dissolved gas analysis (DGA) is a method of monitoring the condition of electrical transformers and related oil filled equipment. The oil used in transformers as coolant and insulator has gases dissolved in it due to aging and faults inside the transformer. Different faults in transformers create fault gases of different kind, e.g. CO, CO2, CH4, C2H6, C2H4, and C2H2. The extraction and analysis of these gases can give early indication of transformer failures.
The extraction of gases, the removal of the dissolved gas from oil, can be done in several ways. The solubility of gases in oil differs based on gas molecules, the insulation matrix, temperature and pressure. By manipulating these factors the extraction process can be controlled. Photoacoustic method allows analysis from low gas volumes and the cantilever enhanced photoacoustic setup can be used in a wide range of pressure and temperature. This versatility enables the use of different methods for extraction.
Furthermore the high sensitivity of cantilever sensor allows the use of relatively small broadband infrared (IR) sources and small sized IR filters. Even multiple filters can be used for one gas, which, combined with advanced gas signal models and analysis algorithms, gives sub ppm detection limits and a high dynamic range for fault gases.