scholarly journals Parameters Affecting the Polarity Inversion of the Vertical Electric Lightning Field to the CN-Tower

2021 ◽  
Vol 8 (1) ◽  
pp. 117-124
Author(s):  
Asmaa Lakhdar ◽  
Abdenbi Mimouni ◽  
Zineddine Azzouz
Keyword(s):  
Electromagnetic Compatibility ◽  
Source Model ◽  
Two Dimensions ◽  
Voltage Source ◽  
Horizontal Distance ◽  
Return Stroke ◽  
Lightning Channel ◽  
Dual Polarity ◽  
2D Fdtd ◽  
High Structure

The aim of this paper is to perform a parametric study in order to analyze factors having an effect on the vertical lightning field polarization to the CN-Tower in Canada, and estimate with numerical simulation, the horizontal distance for which the reversed polarity will occur. The calculation is performed using the Finite-Difference-Time-Domain technique in two dimensions (2D-FDTD), the spatial-temporal current propagation through the lightning channel and through the high structure is represented by the lumped-series voltage-source model. The obtained results show that the vertical electric lightning field behavior has a dual polarity, the transition from a negative waveform to a positive one is observed at different observation points localized near the elevated object influencing by each modification made to the tower-parameters, the medium conductivity and the return stroke speed value. These results can contribute to the understanding of the lightning-phenomenon and allow to solve the problems of electromagnetic compatibility.

scholarly journals Evaluation of Horizontal Electric Field from the Lightning Channel by Electromagnetic Field Equations of Moving Charges

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Yunfeng Zhang ◽  
Erchun Zhang ◽  
Jialiang Gu
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Finite Conductivity ◽  
Lightning Flash ◽  
Horizontal Distance ◽  
Field Equations ◽  
Long Distance ◽  
Return Stroke ◽  
Lightning Channel ◽  
Soil Conductivity

The horizontal electric field from the lightning return-stroke channel is evaluated by the electromagnetic field equations of moving charges in this paper. When a lightning flash strikes the ground, the charges move upward the lightning channel at the return-stroke speed, thereby producing the electromagnetic fields. According to the electromagnetic field equations of moving charges, the detained charges, uniformly moving charges, and decelerating (or accelerating) charges in each segment of the channel generate electrostatic fields, velocity fields, and radiation fields, respectively. The horizontal component of the sum is the horizontal electric field over the perfectly conducting ground. For the real soil with finite conductivity, the Wait formula is used here for the evaluation of the horizontal electric field over the realistic soil. The proposed method can avoid the oscillation of the fields in the long distance by the FDTD method and the singularity problem of the integral equation by the Sommerfeld integral method. The influences of the return-stroke speed, distance, and soil conductivity on the horizontal electric field are also analyzed by the proposed method. The conclusions can be drawn that the horizontal electric field decreases with the increasing of the return-stroke speed; the negative offset increases with the increasing of horizontal distance and with the decreasing of the soil conductivity, thereby forming the bipolar waveform. These conclusions will be practically valuable for the protection of lightning-induced overvoltage on the transmission lines.

A Review of Positive and Bipolar Lightning Discharges

2003 ◽  
Vol 84 (6) ◽  
pp. 767-776 ◽  
Author(s):  
V. A. Rakov
Keyword(s):  
Forest Fires ◽  
Return Stroke ◽  
Winter Storms ◽  
Convective Systems ◽  
Lightning Channel ◽  
Different Types ◽  
Mesoscale Convective ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning ◽  
Positive Return

Characteristics of lightning discharges that transport either positive charge or both positive and negative charges to the ground are reviewed. These are termed positive and bipolar lightning discharges, respectively. Different types of positive and bipolar lightning are discussed. Although positive lightning discharges account for 10% or less of global cloud-to-ground lightning activity, there are five situations that appear to be conducive to the more frequent occurrence of positive lightning. These situations include 1) the dissipating stage of an individual thunderstorm, 2) winter thunderstorms, 3) trailing stratiform regions of mesoscale convective systems, 4) some severe storms, and 5) thunderclouds formed over forest fires or contaminated by smoke. The highest directly measured lightning currents (near 300 kA) and the largest charge transfers (hundreds of coulombs or more) are thought to be associated with positive lightning. Two types of impulsive positive current waveforms have been observed. One type is characterized by rise times of the order of 10 μs, comparable to those for first strokes in negative lightning, and the other type is characterized by considerably longer rise times, up to hundreds of microseconds. The latter waveforms are apparently associated with very long, 1–2 km, upward negative connecting leaders. The positive return-stroke speed is of the order of 108 m s−1. Positive flashes are usually composed of a single stroke. Positive return strokes often appear to be preceded by significant in-cloud discharge activity, then followed by continuing currents, and involve long horizontal channels. In contrast to negative leaders, which are always optically stepped when they propagate in virgin air, positive leaders seem to be able to move either continuously or in a stepped fashion. The reported percentage of bipolar flashes in summer storms ranges from 6% to 14% and from 5% to 33% in winter storms. Bipolar lightning discharges are usually initiated by upward leaders from tall objects. It appears that positive and negative charge sources in the cloud are tapped by different upward branches of the bipolar-lightning channel.

Research on Energy Saving Directing at Building Lighting System

2012 ◽  
Vol 253-255 ◽  
pp. 679-683
Author(s):  
Jiang Hong Xie ◽  
Jin Ping Wang ◽  
Ming Xia Shang Guan ◽  
Yang Shao
Keyword(s):  
Energy Saving ◽  
Power Supply ◽  
Supply Voltage ◽  
Current Source ◽  
Source Model ◽  
Voltage Source ◽  
Lighting System ◽  
Work Processes ◽  
Power Supply Voltage ◽  
Optimal Power

The thesis states the building lighting regulated system composition, basic functions and work processes. Based on the compensation principle, making use of transformer controlled voltage source and the controlled current source model, the thesis analyzes the principle of the system voltage. According to the illumination and life span character of the lighting lamps and lanterns in different voltage, the thesis gets the optimal power supply of building lighting system electric lamps and lanterns. Finally, the building indoor lighting using optimal power supply voltage lighting and energy saving rate of building exterior wall using time-varying stabilized voltage control scheme are analyzed and calculated.

Current-versus voltage source model in Josephson effect

1977 ◽  
Vol 63 (2) ◽  
pp. 149-150 ◽  
Author(s):  
J. Kadlec ◽  
K.H. Gundlach
Keyword(s):  
Josephson Effect ◽  
Source Model ◽  
Voltage Source

scholarly journals A New Optimized Localized Technique of CG Return Stroke Lightning Channel in Forest

2015 ◽  
Vol 10 (6) ◽  
pp. 2356-2363 ◽  
Author(s):  
Homayun Kabir ◽  
Jeevan Kanesan ◽  
Ahmed Wasif Reza ◽  
Harikrishnan Ramiah ◽  
Kaharudin Dimyati
Keyword(s):  
Return Stroke ◽  
Lightning Channel
Sign in / Sign up

Export Citation Format

Share Document