Study of flashover phenomena on polluted insulation theoretical models and experimentation

The appreciable number of flashover of polluted insulators, energised with DC voltage, has motivated both theoretical and experimental studies for better understanding of the flashover processes. In order to study these phenomena different mathematical models for pollution flashover have been developed. These include models for sustaining DC arcs on contaminated surfaces, criteria for DC are motion as well as arc reignition models for contaminated AC insulators. The results have permitted to improve the characteristics of the materials and the design techniques employed to realise insulation components. Nevertheless, a lot of problems due to environmental pollution phenomena are not clear sufficiently yet. Typical examples are represented by ignition and propagation phenomena due to difficulties to identity all the parameters involved in pre-discharge and discharge phases. On the other hand, settingup accurate models for the different discharge phases can not always utilise a dedicated experimental validation. In order to obtain more general models, in the paper a partial validation method of analytical discharge models was proposed. The method consider a low number of parameters controllable and reproducible in laboratory tests. In order to validate the method, experimental results are compared with analytical simulations obtained by use of dynamic arc modeling capable to take into account the configuration of an insulator profile at every instant, which plays an important role in the flashover process.