Research on the Degradation Mechanism of Transformer Insulation Pads under the Synergistic Effect of Preload and Thermal Aging

To study the effects of preload and thermal stress on transformer insulation pads during long-term operation, this paper constructs a preload-thermal aging synergistic accelerated aging experimental platform. Terahertz spectroscopy and infrared spectroscopy are employed to explore the degradation mechanism of transformer insulation pads under the synergistic effect of preload and thermal aging. By analyzing the changes in dielectric constant and chemical structure in the terahertz frequency range, the study finds that the degradation rate under thermal aging is greater than that under the synergistic effect of preload and thermal aging, which is in turn greater than that under preload alone. The reason for this is that preload reduces the pores and air gaps between the insulation layers and within the pads, lowering the moisture content and slowing down the hydrolysis of cellulose molecular chains. In contrast, thermal aging increases the pores and air gaps between the insulation layers and within the pads, accelerating the hydrolysis and oxidation of cellulose molecular chains. This research provides important scientific evidence for the maintenance and lifespan extension of transformers.