Direct lightning on grounding grids and emc problems

This paper presents simple models that can be computed in seconds and give a good estimate of EMC problems caused by transient current and voltage on grounding grids, which are caused by lightning surges. The TLM (Transmission Line Modeling Method) is employed with a model of underground conductor or transmission line in time domain computational simulations and some examples of problems are considered to illustrate the simplicity and the reliability of the method. This numeric technique has been chosen, because the correct boundary conditions can be obtained easily and the representation of different kinds of loads is achieved.