The flashover phenomenon: an analysis with influence of the thickness of the layer pollution of the high voltage polluted insulators

This paper shows the results of the analysis of the dynamic behaviour of the flashover phenomenon on the high voltage polluted insulators gotten from a mathematical and an experimental model that introduce the variable thickness influence of the layer pollution deposited on the high voltage insulator surface. The analysis of flashover is done by introducing a variation in the thickness of the channel of Obenaus´ model, simulating a layer pollution of variable thickness. The objective is to obtain a better reproduction of the real layer pollution deposited on the insulator that works in the polluted regions. Two types of thickness variation are used: a sudden variation, using a step; and a soft variation, using a ramp; that are put in the way of the discharge. The mathematical model developed can simulate electrical discharges on polluted surfaces with the influence of the variations of the thickness and variations of the voltage polarity of the experimental model. This mathematical model was obtained from the equivalent electrical circuit of Obenaus´ model with geometrical characteristics of this model. The introduction of the thickness variations modifies the resistance value of the pollution simulated layer and the values of the electrical variables of the analysed phenomenon. The results obtained from the mathematical model were compared with the results of the experimental model developed and with results of other publications. This comparison shows that introduction of a ramp makes Obenaus´ model more efficient to analyse the dynamic behaviour of flashover phenomena.