Study on Aging Properties of Resin Impregnated Paper Composite for Dry-type Bushing

With the wide application of dry-type bushing, the insulation deterioration of its main insulating material—resin impregnated paper has been widely concerned. Firstly, the resin impregnated paper insulation material was subjected to constant temperature thermal aging test at 115℃; Then, the dielectric properties and power frequency breakdown of the insulation materials with different thermal aging time were tested; Finally, based on the in-depth analysis of effect of aging on dielectric response in frequency domain, an aging evaluation method based on dielectric modulus analysis was proposed. The results show that thermal aging has a significant effect on the insulation performance of the resin impregnated paper composite. The real part of capacitance of the resin impregnated paper insulation increases significantly in the low-frequency region, and obvious loss peak appears in the curves; Compared with the new sample, the power frequency electrical strength of thermal aged for 168, 336, 504, 672, 840 and 1008h decrease by 4.34%, 5.79%, 8.88%, 12.6%, 13.84% and 16.53%, respectively; The dielectric modulus spectrum has obvious relaxation peak in the low-frequency region, the integral area of the imaginary part of dielectric modulus (Amc%) can characterize the aging degree of the resin impregnated paper insulation, and Amc% has a high exponential function relationship with the aging time. It is helpful to realize the quantitative evaluation of aging status of resin impregnated paper insulation.