The Effect of Oil Flow State on The Leakage Current of Oil-Paper Insulation

Converter transformers used oil circulation to enhance heat dissipation, and the state of flowing oil has a significant effect on the properties of oil-paper insulation. In this paper, the oil-paper insulation between flat electrodes was used as an experimental model, and the effects of different oil velocities and voltage on the leakage current and the space charge distribution were investigated. Under the different electric field, the paper side leakage current and the interface charge of the sample with an oil flow were larger than those in the static state. With the increase of the flow velocity, the leakage current and interface charge first increased and then decreased. This phenomenon was explained in terms of the ionization effect, which was influenced by the flow velocity and thus led to the change of the interface charge accumulation.