Diagnosis for aging degradation of insulating paper in power transformers by measuring the refractive index of cellulose fibers

His paper proposes a new diagnosis method for aging degradation of insulating paper in power transformer. We took note of cellulose fibers that are suspended in insulating oil in transformers as samples that could be useful for assessing the aging degradation of insulating paper in transformers. We would like to note that the thermal degradation of insulating paper accompanies the crystallization of cellulose fibers. In this paper, we used the dispersion staining method to investigate the relationship between degradation and crystallization of cellulose fiber.