What does the furan test of transformer oil measure?

The furan test of transformer oil measures the presence of furan compounds, which are indicative of paper insulation degradation within transformers. As the insulation ages or undergoes thermal stress, cellulose breaks down, producing furan derivatives. This test helps assess the condition of the transformer insulation system and predict potential failures, allowing for timely maintenance or replacement decisions. Monitoring furan levels is crucial for maintaining transformer reliability and preventing costly outages.