Furfural analysis is gaining popularity in the recent trend of transformer insulation strength assessment, transformer remnant life estimation or related research field. This is due to its direct connection with the solid insulation strength in the power transformer system. ASTM D5837 is the widely used standard method in detecting furan derivatives using HPLC equipments or gas chromatography-mass spectrometry equipment, which is also used by the experts in the industries. the detectable furanic compounds in transformer oil with the current available technology are 2-furan, 2-furfurol, 5-hyroxy methyl-2-furfural, 5-methyl-2-furfural and 2-acetylfuran etc.

Although it has been known for some time that the hydrolytic degradation of cellulose can lead to the formation of furanic compounds, particularly 2-furan, the mechanism by which this occurs is still unclear. However, it is proposed that furans are produced from pyrolysis mechanism of levoglucosane and hydrolytic degradation of cellulose in the paper. Levoglucosane, the precursor of furanic compounds, is the by-product due to thermal degradation of cellulosic paper at temperatures higher than 130C.

Transformer oil furan analysis plays an essential part in transformer health condition monitoring. Furans are generated in the case of an abnormal hot spot inside the transformer and a high concentration of these compounds indicates that the transformer might have reached the end of its life of operation. The result is also a complement to DGA; providing more data in transformer remnant life estimation. In other words, a regular monitoring of furans concentration available in transformer oil can avoid incipient faults.