| Breakdown channels in ground, formed by lightning strikes contacting the earth, may be intercepted by buried cables which can lead to their damage. Assessment of the possibility of such occurrences is important in the design of suitable protection schemes and mitigating strategies. A review of the existing literature indicates that they leave considerable room for improvement, especially in the prediction of lightning propagation paths which have an effect on the current impacting the cable and therefore the resulting over-voltage.; Based on data collected by the author in indoor and outdoor experiments, a probabilistic, E-field based numerical simulation model is proposed to predict lightning breakdown paths in soil. In the model the probability of growth of these paths depends on the local transient electric field; the interaction between growth of the path and the transient electric field distribution is considered. The influence of lightning current magnitude, geometric configuration, soil parameters and non-homogeneity are recognized by the model.; The usefulness of the proposed path prediction model is demonstrated by its application to the complete assessment of the effect of lightning strikes on buried cables. Such a technique provides probabilistic information on the over-voltage produced in struck cables with soil characteristics and geometrical configuration as parameters.; The conclusions resulting from simulations are in broad qualitative and quantitative agreement with field and experimental observations and, in general, explain well certain aspects of breakdown in dry and wet soils. |
