Clean fog rapid procedure test of artificially and naturally polluted HVDC porcelain barrel insulator

The application of the clean fog rapid test procedure to artificially and naturally polluted HVDC porcelain apparatus insulators was studied. The influence of parameters such as salinity (in the case of artificial pollution the influence of the amount of kaolin and salt and of the kaolin/salt ratio in the slurry) and the rate of fog injection was examined. The results from these tests were compared to those obtained with the up and down test procedure. The clean fog rapid test procedure results show that the minimum flashover voltage obtained for an insulator is related both to the salt deposit density (SDD) and to the kaolin to salt ratio (KSR) in the slurry. The results for the cases examined are in agreement with the results obtained with the standard up and down method. A controlled fog test procedure is proposed