An improved return stroke model with specified channel-base current
- Univ. of Florida, Gainesville (USA)
If a typical measured channel-base current is assumed and if the discharge time constants are properly chosen, electric and magnetic field wave shapes calculated with the model exhibit all the significant characteristics of measured fields. Comparison of typical characteristics of field wave shapes from natural and from artificially initiated (triggered) lightning indicates a faster discharging process for triggered lightning. Depending on the breakdown time constant, the return stroke speed determined using the well-known formula for the transmission-line model, with inputs being the peak electric field and peak current from the present model, are in the range from about 50 to 90% of the return stroke speed assumed in the present model. The corresponding transmission-line model speeds determined from the peak derivatives of the electric field and current are in the range from about 140% to 160% of the assumed return stroke speed. These results supply some indication of why transmission-line model speeds determined from the ratio of measured peak current and field derivatives in triggered lightning are greater than the speeds determined from the ratio of measured peak currents and fields. For a given channel-base current, the initial peak electric field and field derivative derived from the model increases as the height above ground of the strike point increases. If natural lightning strikes an elevated object, the increase of the initial electric field and field derivative can result in an additional substantial error in determining the peak current and peak current derivative from the transmission-line model.
- OSTI ID:
- 6123812
- Journal Information:
- Journal of Geophysical Research; (USA), Vol. 95:D9; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Influence of Channel Base Current and Varying Return Stroke Speed on the Calculated Fields of Three Important Return Stroke Models
Derivation of return stroke parameters from the electric and magnetic field derivatives
Related Subjects
POWER TRANSMISSION LINES
MATHEMATICAL MODELS
BREAKDOWN
CALCULATION METHODS
ELECTRIC CURRENTS
ELECTRIC FIELDS
HEIGHT
LIGHTNING
MAGNETIC FIELDS
WAVE FORMS
CURRENTS
DIMENSIONS
ELECTRIC DISCHARGES
240500* - Power Transmission & Distribution- Environmental Aspects- (1990-)