Dissolved Gas Analysis (DGA) in Transformer Condition Monitoring

Dissolved Gas Analysis 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, for example CO, CO2, CH4, C2H6, C2H4, and C2H2. The extraction and analysis of these gases gives highly reliable early indication of transformer failures.

The extraction of gases, i.e. 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 gas concentration analysis from very low gas volumes, and furthermore, the cantilever enhanced photoacoustic setup can be used in a wide range of pressures and temperatures. This versatility supports the use of different methods for gases from oil extraction when using Gasera’s cantilever enhanced photoacoustic spectroscopy for gas analysis in the transformer condition monitoring system.

The ultra-high sensitivity of Gasera’s patented cantilever sensor allows the use of relatively small broadband infrared (IR) sources and small sized optical IR filters. Even multiple filters can be used for one gas, which, combined with advanced gas signal models and analysis algorithms, gives parts-per-billion level detection limits and a wide dynamic detection range for the fault gases.