An Evaluation and Correlation Study of Oil and Solid Insulation in Power Transformers using Composite Index Considering Operating Age.

Power transformers, integral to electrical systems, necessitate substantial investment. Their operational longevity hinges critically on the quality of their insulation system. This study focuses on evaluating the condition of both oil and solid insulation within transformers, which is vital for preventing operational failures. The condition of oil insulation is influenced by a blend of chemical, electrical, and physical properties, while the aging of solid insulation is an irreversible process that ultimately dictates the end of a transformer's service life. Recent advancements, notably the guidelines from CIGRE TB 761, have provided a comprehensive framework for assessing transformer insulation. These guidelines employ a multi-parameter approach to derive a consolidated insulation index. This study applies the CIGRE TB 761 methodology to a population of 357 power transformers, facilitating a detailed comparative assessment of the oil and solid insulation. This paper discusses the methodology used and presents the results, highlighting the evaluation of both oil and solid insulation aspects. Furthermore, it investigates the relationships between various testing parameters and the overall insulation index in relation to the transformer's age. For oil insulation, key parameters include interfacial tension, color, breakdown voltage, acidity, and moisture content. Solid insulation assessment predominantly revolves around parameters such as methane, ethylene, ethane, carbon monoxide, carbon dioxide, CO2/CO ratio, and DP value. This study also correlates the insulation condition in power transformers to the operational age, and thereby contributing to more effective monitoring and maintenance strategies. [ABSTRACT FROM AUTHOR]