How does furan analysis assess transformer paper insulation aging?

Furan analysis measures furanic compounds dissolved in the oil that are produced when cellulose paper insulation thermally degrades. As paper breaks down, it releases characteristic furans into the oil. Higher furan levels and rising trends typically indicate advanced insulation aging and reduced mechanical strength of paper, which can limit overload capability and increase failure risk. Furan results are interpreted with transformer temperature history, moisture, and DGA because oil treatment can affect concentrations. It is a valuable tool for end of life assessment and asset management planning.