The Effect of Epoxy Resin Cracking Under Low Temperature-Stress Coupling Action on its Electrical Properties

The epoxy coatings of cables in northern regions have been subjected to long-term combined effects of low temperature - stress, resulting in frequent cable failures. To examine the influence of combined low-temperature stress on the electrical characteristics of epoxy resin, this text conducted an aging test of epoxy resin under low-temperature-stress combination, and studied the influence of combined aging on the microstructure and electrical properties of epoxy resin. Furthermore, an electric thermal mechanical multi field coupling model was established to explore the mechanism of the influence of epoxy defects on the insulation of 535kV cable accessories. The results indicate that identical aging duration, as the stress gradually increased from OMPa to 0.3MPa, the cracks of the epoxy resin gradually deepened and widened, and the breakdown voltage gradually decreased, besides, the change in breakdown voltage was particularly significant at a stress of 0.3MPa. Furthermore, the electric field near the epoxy defect of the 535kV cable accessory increased with the increase of the crack.