Influence of Moisture on Dielectric Responses of Oil-Impregnated Paper Condenser Bushings

To address the moisture ingress that usually occurs as one of the main faults in oil-paper condenser bushings, the effects of moisture has been simulated on real-life bushings in the present study. Based on the actual production process, 12 bushings with artificially simulated moisture ingress have been prepared in the workshop. By controlling and rearranging the drying process of insulation paper and condenser bodies, two manners of moistening have been simulated, one of which corresponds to the moisture generated from ageing and diffused outward, while the other simulates the moisture permeated from outside and diffused inward. Besides, the difference in the gradient of moisture content has been guaranteed through the simulation. FDS and PDC tests have been applied on the prepared bushings, and the dielectric response characteristics under conditions of the different moisture content and different moistening modes have been analyzed.