Freeing power transformers from gassing and aging of oil

While the gassing of oil, as determined by periodic dissolved gas analysis (DGA), is attributed to an incipient electrical failure, for the gradual deterioration of paper insulation its aging process is considered to be responsible. These deficiencies, both of which negatively affect the service reliability of high voltage power transformers, are currently perceived as two independent phenomena. In reality, studies indicate that they are interrelated. New laboratory techniques developed for improved monitoring of oil decay, show that gassing has hidden side effects. The outcome of random secondary chemical reactions that follow the decomposition of hydrocarbon chains, also suggest that gassing might be a self-sustained process. This paper describes the relationship between the purity of oil and its stability under electrical stress, as well as the means necessary for maintaining the liquid insulation in pristine condition throughout the entire lifetime of a power transformer.