Study of electric field equilibrium characteristics in IOCT considering different equalizing cage structure and temperature

Abstract

The dielectric parameters of oil-immersed insulation paper, semi-conductive paper and mineral oil were measured at different temperature. The quantitative analysis about the influence of the equalizing cage density on the Inverted-type Oil-immersed Current Transformer (IOCT) electric field distribution was studied, and the temperature dependence of the insulation material dielectric parameters were taken into consideration. In high temperature conditions, the oil-paper damage of IOCT insulation system is generally not caused by electric breakdown but heat aging. The maximum electric field strength of oil-paper I is approximately reduced by 12.84%, and that of the oil-paper II is reduced by 0.35%, after the equalizing cage density is increased. The increasing of the equalizing cage density will be beneficial to the electric field equidistribution of the IOCT insulation system.