Condition Monitoring Techniques of Dielectrics in Liquid Immersed Power Transformers - A Review

With the developments in transformer design, their methods of maintenance also need to be updated. A shift from the traditional time-based maintenance to condition based maintenance is required for lifetime economic management of transformers. As the aging of a transformer is directly related to insulation deterioration, the estimation of insulation health is required to analyze the condition of the transformer. This paper reviews various methods of dielectric analysis, including chemical based methods such as Dissolved Gas Analysis, and dielectric response analysis. Several techniques for interpretation of results is also analyzed here. The present trends in condition monitoring with both online and offline monitoring techniques are also presented here. With the active research being conducted in this field, the current developments in this field are identified and surveyed, which are required for future advancements in this subject.