Conduction of water clusters in modified aged oil

Abstract

SUMMARYDissolved water in insulating liquids has been regarded as a kind of impurity that degrades electrical properties. Recently, the state and the behavior of water molecules in liquid have been measured by infrared methods, making it possible to analyze where water molecules are bound to dielectric molecules and how many molecules gather around polar radicals on the alkyl chain.In the case of transformer oil, which consists almost entirely of saturated hydrocarbons, the content of oxidation products is gradually increased by aging during use. These oxidation products include polar radicals such as carbonyl and ketone radicals. When water dissolves in such oil, water molecules interact with these polar radicals to form water clusters, which can make the conductivity increase. In the research reported here, partially oxidized hydrocarbon was mixed with saturated hydrocarbon and the effect of water clusters around ketone radicals on the conductivity was investigated. When the content of oxidation products was less than 10%, the conductivity did not increase with an increase in the amount of water. But when the ratio exceeded 10%, specific kinds of water clusters increased the conductivity. It appears that these clusters consist of water molecules gathered around one ketone radical.

The effect of oxidative and paper degradation impurities on partial discharge characteristics of hexadecane

“…The main ageing effects seen in transformers are associated with oxidation of the fluid and overheating of the cellulose. Oxidation of the fluid reduces volume resistivity, increases dielectric loss, reduces interfacial tension, increases total acid number, increases moisture (from celluose degradation), and increases dissolved gases within the fluid [2][3][4][5][6][7][8][9]. Thermal and oxidative degradation of the paper causes a decrease in the degree of polymerization and generation of furanic compounds and moisture [10][11][12][13][14][15][16][17][18].…”