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CO2 adsorption effect on breakdown strength of cellulose paper

The insulation performance of Ultra-High voltage (UHV) transformer is urged to be improved in order to meet the increasingly extreme operational conditions that UHV transformer serves. Carbon dioxide (CO2), an electronegative, non-combustible gas, is applied to improve the electric breakdown strength of UHV transformer insulation by adsorbing on cellulose paper. First, the Brunauer-Emmett-Teller measurement is utilized to find the CO2 adsorption quantity and adsorption heat of different cellulose paper. The relationship between ply bond strength and the quantity of CO2 adsorption is studied. Then, Alternating Current (AC) breakdown test show the breakdown strength is improved by CO2 adsorption. In addition, this paper compares the differences of AC breakdown strength between different cellulose paper, explaining these differences based on ply bond strength and apparent density. Further, in this paper, CO2 adsorption is also effective to oil-paper insulation which is widely used in UHV transformers. Finally, by comparing the breakdown strength and dielectric loss of Hydrochloric acid and Acetic acid treated paper pulp, the Acetic acid treatment shows promising future in cellulose paper manufacture. This research is conducive to promote both cellulose and oil-paper insulation performance and prolong the lifespan of UHV transformers.