Effect of ATA Additive on Oil-Solid Surface Flashover Characteristics Under Dc Electric Field

During the operation of the converter transformer, the oil-paper insulation flashover problem seriously affects the safety of HVDe transmission. In order to improve the flashover property along the oil-paper interface, an electrode configuration was adopted to test the flashover voltage under a quasi-uniform field distribution. Moreover, 3-Amino-1,2,4-Triazole (AT A) was used as an additive in oil and its effects on the surface flashover characteristics in two types of oil and solid combinations were investigated. According to the experimental results, the oil-solid surface flashover voltage fluctuates at different electrodes gaps, when there is 3-Amino-1,2,4-Triazole (AT A) in the insulating oil, the voltage ratio (Uf/Ub) which is the ration of the flashover voltage to the breakdown voltage of oil is significantly improved. Moreover, some differences exist in the sample with different combinations of oil and solids. The difference of voltage ratio between oil (ATA)-paper and pure oil-paper combinations is the largest, and which is the smallest between oil (ATA)-polytetrafluoroethylene (PTFE) and pure oil-PTFE combinations. These phenomena are explained in terms of the effects of AT A on the charge accumulation and distribution in the electric double layers (EDL) of the oil-solid interfaces.