Comparison of Different Residual Resistance Calculation Methods used in Predictive Insulator Flashover Models

The present paper presents an investigation on the comparison between the numerical and mathematical calculation of the residual resistance of a conductive layer in series with an electrical arc, as described by the Obenaus flashover model. For this purpose, this study has focused on the analytical residual resistance formulation proposed by Wilkins, whose results were compared to numerical calculations performed on a uniform ice-covered post insulator with complete and truncated geometry. The numerical simulation was performed using a previously developed numerical dynamic mono-arc predictive FOV model based on the finite element method. The results obtained showed that the Wilkins formulation underestimates the residual resistance by an average discrepancy of 13% with a maximum value of 34% during the final jump. For the truncated geometry, the residual resistance is overestimated by an average discrepancy of 5% with a maximum value of 8.6% during the final jump. From the AC FOV results, it was found that the use of the complete geometry coupled with the numerical calculation provides the more accurate predictive results with an average discrepancy of 3.9% as compared to the experimental results.