부산대학교 도서관

Power transformers are one of the most critical components of power systems, and failures often result in significant economic loss from the interruption of power and damage of assets. The establishment of maintenance programs that signal abnormal conditions in transformers is essential for the reliable operation of these equipments. However, in a competitive market, it is important to maximize investments by depleting the remaining life of the equipments before replacing them. The end of life of a transformer comes about by aging of its solid insulation, which is mainly Kraft paper, pressboard, and wood, and these materials age mainly by hydrolysis reactions. Although transformer lifetimes are considered to be about 30 years, experience shows that some transformers remain in service for more than 50 years [1]. Aging of cellulosic insulation depends mainly on operating temperature, moisture, oxygen, and acids. The value of these factors depends on the operating conditions and maintenance practices, which are not always accurately quantified. Having a method to estimate the remaining life of a transformer is essential for owners to assess the risk of keeping a transformer in service or the necessity of replacing it. Unfortunately, estimating the remaining life of transformer insulation is not an easy task because it is not possible to extract paper samples from the active part of the transformer to make direct determinations, and estimations are always based on indirect estimations. On the other hand, the transformer temperature is not homogeneous, so the condition of the paper varies within the transformer, which makes the analysis even more complex. The determination of the furanic compounds content in the transformer oil is one of the more valuable methods to diagnose the aging condition of transformer solid insulation [2]. Unlike other markers, for example CO or CO 2 , which are produced during the degradation of cellulosic insulation but also mineral oil, furanic compounds are exclusively generated as a by-product of the aging reactions of only cellulose insulation, and that makes the diagnosis more reliable.