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U.S. Department of Energy
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Transient effects from lightning. Lightning protection of solar photovoltaic arrays. [VB40, VE40, HB40, and HE40 codes for calculating electromagnetic fields from lighting discharges]

Technical Report ·
OSTI ID:5607000
Lightning return strokes to ground and K changes in intracloud discharges are characterized by surges of current along ionized conducting channels. The current gives rise to transient electric and magnetic fields which are potentially damaging to systems that may be sensitive to transient disturbances. Experimental data available in the literature is used with a simple transmission line model of the discharge current to obtain estimates of the fields produced by vertical or horizontal lightning strokes. The model treats the discharge channel as a lossless uniform transmission line driven by a source at one end. The theory of pulsed linear antennas is then directly applicable and is used to compute the fields. The time and space dependence of the current pulse are assumed known and the current travels unattenuated and at a known velocity along the channel. Reflections are ignored by assuming matched terminations at the channel end points. Field predictions based on this simple lossless transmission line model have been found to be in reasonable agreement with experimental measurements obtained at ground level. Although more rigorous models of the channel current have been investigated, the lossless case appears to provide an adequate description of the electromagnetic fields. In view of the uncertainty involved in specifying the lightning channel parameters required in the calculations, it is felt that the use of the lossless model is in keeping with the current state of knowledge of lightning phenomena. FORTRAN programs for computation of the electric and magnetic fields from vertical or horizontal channels have been prepared for use with a CDC 7600 computer. The codes are described in the Appendix. (WHK)
Research Organization:
Mission Research Corp., Albuquerque, NM (USA)
DOE Contract Number:
EY-76-C-04-0789
OSTI ID:
5607000
Report Number(s):
SAND-79-7051(Vol.2)
Country of Publication:
United States
Language:
English