Grounding transient response of lightning protection GTIERRAS software

Abstract

A computer program developed in Matlab (GTIERRAS) from an electromagneticbased model is used to assess grounding impedances and the behavior of grounding electrodes of arbitrary shapes under lightning impulses. Impedance, currents and voltages, or other electric variables of the grounding system can be presented as well in frequency or in time domain with the use of Fast Fourier Transform. The generality of the model allows its use for assessing lightning overvoltages, but also for other typical transients associated with electromagnetic compatibility problems. Results show the influence of some variables on the response of grounding system and shed light on some differences that must be taken into account when applying criteria based on low frequency performance to groundings stressed by surges. Calculation examples and comparison with results from other authors are presented and analyzed so as to illustrate some grounding behaviors that by no means are evident. Effects of electrode geometry and soil resistivity, as well as of wave front and number of injection points are also investigated. Results of touch and step potentials are shown. A study of a lightning protection system is presented as an extension of the model application capabilities. Some conclusions useful for grounding system design are derived.

Keywords

• grounding system
• overvoltages
• lightning
• modeling
• electromagnetic compatibility