Research on the Influence of Thermal Aging on the Frequency-Domain Dielectric Response of Insulation Materials for Dry-Type Bushing Cores

Dry-type bushings are widely used in high-voltage equipment such as transformers, where their insulation performance is crucial for the safe operation of the equipment. During actual operation, the epoxy resin impregnated paper (RIP) material in the core of dry-type bushings is subjected to a combination of thermal, electrical, and mechanical stresses over a long period, leading to a decline in its insulation performance and affecting the reliability of bushing operation. This paper systematically analyzes the dielectric properties of RIP material at different aging stages through laboratory-simulated thermal aging processes. The main contents include: establishing a homogeneous sample preparation platform and a thermal aging experiment platform to conduct aging treatments on RIP materials for different durations; measuring and analyzing the loss factor and complex dielectric constant of RIP materials with varying degrees of aging using frequency domain dielectric spectroscopy (FDS) testing technology; the experimental results show that as the aging time increases, the loss factor and complex dielectric constant of RIP materials significantly increase, and a notable upward shift in the peak of the real part of the complex dielectric constant at specific frequencies is observed, providing a new direction for the aging assessment of RIP insulation materials in bushings.