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Lightning Current (lightning + current)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Comparison of electromagnetic field for two different lightning pulse current models

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2001
A. Andreotti
In this paper the electromagnetic field produced by a lightning current analytically described by the so called double exponential model is compared with the field produced by the same current (same peak, rise and decay time) analytically described by the model proposed by Heidler. The exponential model has been widely used in literature for its simplicity and its relatively good accuracy. The Heidler model is more complex, but removes the main problem shown by the double exponential: the non-zero derivative at the beginning of the lightning pulse in contrast with the physical phenomenon. In the lightning electromagnetic pulse (LEMP) simulations both models are now used. In the paper we aim to make a comparison between the two. In particular we show that the two models are fairly equivalent in the frequency range up to 2 MHz, namely the range of interest of typical lightning phenomena. In addition, the double exponential model is shown to be conservative for higher frequencies. [source]

Some Parameters of Correlated Current and Radiated Field Pulses from Lightning to the Gaisberg Tower

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 1 2010
Hannes Pichler Non-member
Abstract Simultaneous measurements of lightning current and associated radiated electromagnetic field are of fundamental interest for various applications in lightning research. These data can be used for the evaluation of return stroke (RS) models or to investigate the so-called tower effect when lightning hits an elevated object. In this paper, we show the results of simultaneous measurements of current pulses from lightning strikes on the instrumented Gaisberg tower (Austria) and the correlated vertical E-field components at a distance of 78.8 and 108.7 km, respectively. We have analyzed some main lightning current parameters (peak current Ip, 30,90% rise time TI_30-90, and full width at half maximum TI_FWHM and the time-correlated field waveform parameters (Ep, 30,90% rise time TE_30-90, TE_FWHM, and the peak-to-zero time TE_PTZ. With a geometric mean of TI_FWHM = 19 ,s and Ip = 9.6 kA (N = 73) of the RS current pulses used in this study, those strokes are very similar to the strokes in triggered lightning in Florida and Alabama1. With a TE_PTZ of about 10 µs, the zero-crossing time of the radiated E-fields from the tower strokes are significantly shorter than the typical values of 30 , 40 µs (e.g.2). Correlation between the current and field parameters TI_FWHM versus TE_FWHM and TE_PTZ, respectively, is low (R2 = 0.29 and 0.14). We assume that the relatively short lightning channel in the case of the RSs in object-triggered upward flashes is the main reason for the observed short zero-crossing time. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Skin burn, bilateral iridocyclitis and amnesia following a lightning injury

ACTA OPHTHALMOLOGICA, Issue 5 2004
Lone K. Sommer
Abstract. Purpose:,To describe a case of lightning injury restricted to the eyes and facial skin. Methods:,Case history describing the clinical examination of a 54-year-old woman. Results:,Following a lightning stroke the patient suffered from a sharply demarcated facial skin burn and bilateral iridocyclitis with raised intraocular pressure. Initially she had amnesia regarding the incident. She recovered on symptomatic treatment, with dry eyes as the only sequela. Conclusion:,We suggest that a lightning current travelled over the outside of the patient's body facilitated by her wet raincoat, a so-called flash-over. Thereby, she was spared from more severe injury, and only the exposed areas of the face and eyes were affected. [source]

Effects of moisture content, impulse polarity and earth electrode's dimension on dry and wet sand under high voltage conditions

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2008
N. Mohamad Nor
Abstract The study on the physics of discharges in soil and performance of earthing networks subjected to lightning currents are important in order to improve the reliability of electrical systems and to obtain better electrical models of earthing systems. The soil characteristics of various moisture contents under high-impulse currents have been well studied in previous studies. In this present study, fast impulse generator is used to investigate the dry soil characteristics in two cylindrical test cells of different outer radii; 15 and 20,cm under high magnitude fast impulse conditions of both impulse polarities. This allows to study the characteristics of dry soil under high-impulse current conditions, and allows a comparison between the dry and wet soil characteristics under high-impulse conditions such as before and after breakdown of the test cell. In this study, the effects of impulse polarities, moisture content in soil and the outer dimensions of test cell on the soil characteristics under high-impulse currents were investigated. Copyright © 2007 John Wiley & Sons, Ltd. [source]