Investigation of Spark Discharge in the Ground on Reproduction a Lightning Current Pulse by Means of EMG

Lightning damage to large or sophisticated systems, such as electrotechnical facilities and devices, communication systems and radio-electronic equipment thereof, etc. is often observed. Problems on lightning protection are of a specific importance, when the question is of such higher hazardous facilities as ammunition dumps, including nuclear and other military equipment [1,2]. Results of a number of experiments on man-made initiation of lightning performed in underground nuclear weapon stockpiles at Sandia National Laboratory, have shaken the confidence of the invulnerability of facilities equipped with standard lightning protection systems [3]. The conventional lightning protection systems consist of lightning arrestor rod to direct lightning strokes to a selected point away from the vulnerable building structures; current-conducting line to direct current pulses through the building to the ground without electrization of building infrastructures; grounding system to dissipate electric energy of the lightning in ground. Of these components, the grounding system is of primary importance, as the grounding quality defines the value of the current bypassing the vulnerable circuits and its components via the lightning protection system. In the literature, there are data on non-linear character of variation in impedance of the grounding systems at higher lightning currents. The importance of explicit study of grounding device parameters is also dedicated by the hazard of breaking down the lightning discharge through the spark channel spreading over the soil surface [4, 5]. The integral part of the task of constructing reliable lightning protection systems is the development of installations simulating the lightning discharge that enable to test the reliability of lightning protection systems with all their connections and interactions in real environment. Magnetocumulative generators (MCG) are proposed to be employed as such energy sources [1].