The author presents the results of experimental work carried out to make a comparative evaluation of three different methods of generating very short-tailed lightning impulses (STLI) representative of certain kinds of overvoltages affecting overhead lines. These methods, called B, H and I, are all variants of the Marx circuit. B is one of the standard configurations of the Marx circuit, namely that which provides for an external resistance only. H is a modification of the impulse test plant, which consists in switching in the tail branch through a spark-gap. I is yet another modification of the impulse generator, which can be obtained by series-connecting an inductance of properly chosen value to the tail resistance. All three solutions are shown to solve elegantly the problem of generating STLI with good voltage efficiency and acceptable waveshapes.
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