The experience of DP and furan in remnant life assessment of power transformer

Transformer life depends on the life of the oil impregnated paper insulation system. Degradation of the cellulose insulation is an irreversible process. Chemical reaction of cellulose cause opening of glucose rings providing free glucose molecules, water, CO2 and organic acids. These glucose monomers further decompose and produce furanic compounds as end products. DP and furan tests are used to identify the extent of ageing of the cellulose in paper insulation of the transformer. Many authors including Chendong.I, have reported the empirical relations relating furan content with DP. These empirical relations are finding application in estimating the consumed life of the transformer. We are doing extensive DP and furan analyses for remnant life assessment of transformers. This paper reports our experiences with DP and Furan as a diagnostics tool as applied to a high voltage transformer. Our data is based on the DP test results conducted on the samples collected at various strategic locations such as main lead, canopy, barrier boards etc. The furan data collected over several years were analyzed. The past trend is used to determine the deterioration rate. All these results are correlated and the same is presented in this article.