Laboratory Study of the Lightning Attractive Width for Transmission Lines

ABSTRACT

This research focuses on an investigation of the attractive width of high voltage transmission lines to lightning strokes. In order to design the optimal lightning protection, the estimated number of lightning flashes to the line, which is based on its attractive width, needs to be determined. The investigation was performed using experiments with tested models at the Mississippi State University High Voltage Laboratory. For laboratory experiments, a total of 1,900 negative and positive switching impulse voltages were applied to a conducting rod, which represented a lightning downward leader. Different tested models of transmission lines on a scale of 1:100 were used. The effect of overhead ground wires, phase conductors, and the magnitude and polarity of lightning strokes were studied. The attractive width increased gradually with the height of overhead ground wires as well as the magnitude of the lightning stroke current. Impulse polarity had an impact on the attractive width and the attractive width for negative polarity was larger than that for positive polarity. The experimental results satisfactorily coincide with other published works, based on different methods and also with the actual transmission line observations. The new expressions of the attractive width of transmission lines, based on the experimental results, were established. The accurate estimation of the attractive width can help electric power utilities plan transmission systems reliably and economically. The detailed description of the background problem, methodology, experimental results, and analysis were presented in this paper.

Keywords:

High voltage, lightning strokes, attractive width, Impulse polarity, Positive Polarity, transmission lines, conducting rod.