Lightning Currents Research Articles

Lightning Current Measurement Method Using Rogowski Coil Based on Integral Circuit with Low-Frequency Attenuation Feedback.

A lightning current measurement method using a Rogowski coil based on an integral circuit with low-frequency attenuation feedback was proposed to address the issue of low-frequency distortion in the measurement of lightning currents on transmission lines using Rogowski coils. Firstly, the causes of low-frequency distortion in lightning current measurements using Rogowski coils were analyzed from the perspective of frequency domains. On this basis, an integration correction optimization circuit with a low-frequency attenuation feedback network was designed to correct the low-frequency distortion. The optimized integration circuit can also reduce the impact of low-frequency noise and the DC bias of the operational amplifier (op-amp) on the integration circuit due to the high low-frequency gain. Additionally, a high-pass filtering and voltage-divided sampling circuit has been added to ensure the normal operation of the integrator and improve the measurement range of the measurement system. Then, according to the relationship between the amplitude-frequency characteristics of the measurement system and the parameters of each component, the appropriate types of components and op-amp were selected to expand the measurement bandwidth. Finally, a simulation verification was conducted, and the simulation results show that this measurement method can effectively expand the lower measurement frequency limit to 20 Hz, correct the low-frequency distortion caused by Rogowski coils measuring lightning currents on transmission lines, and accurately restore the measured lightning current waveform.

Analysis of the damage effects of carbon fiber composites under the mechanical impact loads of lightning based on a modified simulation calculation method

Mechanical effects contribute significantly to the multiphysical damage of carbon fiber-reinforced polymer (CFRP) composites induced by high-amplitude impulse lightning currents. In this paper, the mechanical impact loads (MILs) of lightning are decomposed into acoustic shock waves from arc channel expansion (AESW), electromagnetic force (EMF), and shockwave overpressure from surface explosion (SESW). A 3D finite element mechanical damage model of laminates was established based on the Hashin–Yeh initial creation and modified stiffness degradation matrix. The model was verified by comparison with pure mechanical impacts. The dynamic response and damage modes of laminates subjected to AESW, EMF, SESW, and MILs were studied and compared. The MILs are exponentially related to the current intensity. The damage effect of laminates under MILs is inversely related to the impact radius. The comparison shows that the effect of the EMF gradually exceeds that of the AESW as the current peak increases and its value is approximately twice that of the latter when the current peak Ip exceeds 165 kA. In contrast, SESW is the primary cause of the damage effect. Over 70 % of the deformation contribution to laminates under MILs comes from SESW (Ip = 165 kA). Furthermore, the strongest SESW is induced by the insufficient thermal conductivity of the CFRP laminates.

Neurotrophic keratitis caused by lightning injury: a case report

BackgroundThis study aimed to report a case of neurotrophic keratitis caused by lightning.Case presentationA 38-year-old man was hit by lightning and suffered eye injury. He eventually developed neurotrophic keratitis.ResultsThe patient’s injury history and burn site were analyzed, and it was judged that lightning directly damaged his cornea, eventually resulting in neurotrophic keratitis. Fortunately, the patient’s vision improved after treatment.ConclusionLightning can cause eye damage, and the clinical manifestations are diverse. Lightning currents cause corneal nerve loss, resulting in neurotrophic keratitis. To maintain corneal integrity and prevent disease progression, early assessment and appropriate treatment are necessary.

Highly conductive and durable nanocomposite hard coatings of carbon fiber reinforced thermoplastic composites against lightning strikes

The growing use of thermoplastic composites (TPCs) like low-melting polyaryletherketone (LM-PAEK) matrices reinforced with unidirectional carbon fiber (CF) in aircraft structures presents a significant challenge in terms of lightning strikes and electromagnetic interference shielding during aircraft operations. This is due to the weak electrical conductivity of TPC structures, which results in widespread damage when struck by lightning. The repair and maintenance of these extended damaged sites can increase operational costs and loss of flights. Several lightning strike protection (LSP) systems have been developed and implemented to address these concerns. This study evaluated a highly conductive coating with a low filler rate for its effectiveness as an LSP solution for TPCs on exterior aircraft surfaces. The TPC panel without any coatings was first studied. Subsequently, the level of conductivity was increased by incorporating the nanoscale conductive fillers, silver-coated copper (Ag/Cu) nanoflakes, with a silver content of 20 wt.% (Ag20/Cu) and 30 wt.% (Ag30/Cu), correspondingly, into the coating at two loadings of 55 wt.% and 70 wt.% in an epoxy carrier for the surface coatings. The behavior of electrical and surface conductivity was thoroughly examined to understand the impact of Ag/Cu with a high aspect ratio and the effectiveness of the LSP solution. In addition, the spray-coated TPC panels underwent rigorous Zone 2A lightning strike testing using simulated lightning current, in agreement with the industry standard of Society of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP) 5412B. Despite the higher resistance due to the lower conductive coating weight, the TPC panels with Ag30/Cu at loading of 70 wt.% achieved better results than those with Ag30/Cu at loading of 55 wt.%. This is evidenced by the minor structural delamination and CF breakage on the front surface, which proposes a new economic route for a sustainable post-processed LSP system in the aviation industry.

Electrical engineering equipment for generating and measuring of complete pulse current of artificial lightning in the conditions of high-voltage electrophysics laboratory

Goal. Decision of problem scientific and technical task on the reliable generating and measuring in the conditions of high-voltage electrophysics laboratory basic component of complete pulse current of artificial lightning with the rationed amplitude-temporal parameters (ATPs) with the use of the modernized generator of current of lightning of type of UITOM-1. Methodology. Bases of the applied electrical engineering, electrodynamics and electrophysics, electrophysics bases of technique of high-voltage and high pulse currents, bases of high-voltage pulse technique and measuring technique. Results. Information, which specify on a decision at Research and Design Institute «Molniya» of National Technical University «Kharkiv Polytechnic Institute» problem scientific and technical task, related to the reliable generating and measuring in the conditions of high-voltage electrophysics laboratory of complete pulse current of artificial lightning, which contains pulse A- (repeated pulse D-), intermediate B- and long-term C- (shortened long C*-) components of this current, is resulted, ATPs which answer the hard technical requirements of normative documents of the USA of SAE ARP 5412: 2013, SAE ARP 5414: 2013 and SAE ARP 5416: 2013. Short information is indicated about the applied electrical circuits of separate high-voltage generators of pulse currents of condenser type of GIC-A (GIC-D), GIC-B and GIC-C (GIC-C*), which it is worked as synchronous appearance on the general electrical loading in composition the modernized powerful high voltage generator of complete pulse e current of artificial lightning of type of UITOM-1, and in-use high-voltage measuring facilities which contain the heavy-current low-resistance shunts of type of SHK-300 for simultaneous registration with their help on examinee on stability to lightning devices objects of aviation and space-rocket technique of ATPs proper component of complete i pulse current of artificial lightning. Technical examples are resulted and the row of results of practical application of the indicated domestic powerful high-voltage proof-of-concept electrophysics equipment is described at the tests of elements of some aircrafts (ACs) on resistibility to the direct action on them of complete pulse current of artificial lightning with rationed ATPs. Originality. A problem is formulated and having the important applied value in area of aviation and space-rocket technique for the leading countries of the world scientific and technical task on the reliable generating and measuring in the conditions of high-voltage electrophysics laboratory indicated component of complete pulse current of artificial lightning with rationed ATPs and concrete electro-technological ways and hardware are indicated for its successful decision. Practical value. The use of the modernized powerful high-voltage generator of complete pulse current of artificial lightning of type of UITOM-1 developed in practice and created in Ukraine will allow to conduct the real verification on resistibility to the action of lightning of different side systems, devices and construction elements, containing metallic and composition materials, both again developed and modernized ACs, that will be instrumental in the increase of vitality of such ACs in the extreme terms of their flight and stay in an electrical active earthly atmosphere with flowing in it storm electrical discharges. References 30, tables 3, figures 20.

Instrumentation for Sub-Ampere Lightning Current Measurement on a Tall Meteorological Tower in Complex Electromagnetic Environment

Measurement of lightning current plays a critical role in the field of atmospheric electricity. Traditionally, Rogowski coils or low-resistance shunts were employed for measuring lightning currents in the range from several amperes up to several hundreds of kilo-amperes, and high-value resistors were utilized for measuring corona discharge currents at sub-ampere levels. However, these approaches were not suitable for continuously recording the vast range of lightning currents. For this sake, we have developed a lightning current measurement system equipped with a shock-tolerant low-noise amplifier module. With the system installed on a tall tower, sub-ampere level currents just before the lightning initiation were observed for the first time. To confirm the authenticity of the recorded currents, the background noise of the measurement system and surrounding environment were identified, and a digital multi-frequency notch filter was proposed for de-noising. Results show that the system can achieve a current identification level of 50 mA even in complex electromagnetic environments, while having a measurement capability of 220 kA.

Influence of lightning current waveforms of cloud-to-ground lightning with multi-return strokes on the lightning withstand level of 500 kV transmission lines

The most common factor causing line tripping is lightning strokes, and it is necessary to conduct research on the lightning withstand level (LWL). The statistical results of lightning location systems (LLS) in various regions of China indicate that the total proportion of cloud-to-ground lightning with multi-return strokes in nature is 30% to 50%. The traditional method of lightning protection design for 500 kV lines based on the current waveform of single lightning strokes is no longer enough to effectively protect existing transmission lines. Therefore, in this paper an electromagnetic transient simulation model for 500 kV lines was established, to compare the LWL difference between single and multiple lightning strokes. The influence of the tower height, the grounding resistance, and the lightning current waveforms are all simulated and discussed. It is found that the back flashover LWL of 500 kV lines is significantly influenced by the lightning current waveforms. Meanwhile, reducing the grounding resistance cannot effectively increase the LWL of 500 kV lines when the tower is too high and the rise time of the lightning current is too short. It is proposed that the lightning current waveforms should be fully considered while calculating the LWL of 500 kV lines, both single and multiple lightning currents, providing a reference for practical engineering construction.

Estimation of lightning overvoltages and critical flashover currents of 150 kV and 400 kV overhead lines: Effects of the CIGRE lightning current waveform parameters

This paper investigates the influence of the CIGRE lightning current waveform parameters on the computation of fast-front overvoltages and critical lightning currents causing flashover of overhead transmission line insulation. The investigation is conducted via ATP-EMTP simulations employing both negative and positive lightning current waveforms corresponding to first return strokes. Typical 150 kV and 400 kV double-circuit overhead lines are evaluated by performing shielding failure and backflashover simulations. The statistical distributions of the parameters required as input for the CIGRE lightning current waveform (front time, maximum steepness, time to half value) are considered in simulations to quantify and analyze their effects; this enables the comparison between negative and positive lightning strikes. The waveform parameters do not affect considerably the critical shielding failure flashover current for both polarities; the most influential parameter in this case is the time to half value. On the other hand, the wavetail duration influences the least the critical backflashover current; the latter is lower for waveforms with faster wavefront (lower front time and higher maximum steepness). The impact of the waveform parameters of positive lightning strikes is more marked for the backflashover case due to their larger variations compared with negative strikes.

Stratified materials for aircraft structure: thermal effect of lightning impact by numerical simulations

This paper studies the effect of lightning impact on aircraft fuselage made of innovative Carbon Fibers Reinforced Composites (CFRC) panels, as an alternative to traditional metal structures. Metal layers are able to dissipate the current generated by lightning impacting the structure, whereas the multilayer CFRC panels are less conductive and therefore have limited capacity for current dissipation. This study presents a time-varying thermal simulation coupled with an electromagnetic simulation, considering different lightning currents that represent both short strokes (i.e., impulses), and long strokes (i.e., square pulses). In order to compare different stoke shapes, the temperature increment resulting from the lightning impact will be assessed through Finite Element Analysis. This approach allows for an assessment of the impact of different strokes on CFRC panels. The model serves as a starting point for future analyses aimed at comparing different technological solutions, beginning with experimental laboratory tests.

High Peak Current Lightning and the Production of Elves

AbstractElves are observed as expanding rings of light in the UV and visible optical bands. They are produced when electromagnetic pulses from lightning discharges interact with the lower parts of the ionosphere. Elves are well known to be associated with high peak current lightning discharges. Here, we use data from the Modular Multi‐spectral Imaging Array (MMIA) of the Atmosphere‐Space Interactions Monitor (ASIM), and search for observations of Elves when high peak current lightning discharges are detected by Vaisala's Global Lightning Detection network GLD360. We present two groups of events; high peak current detections associated with Elves and high peak current detections not associated with Elves. To understand why some current pulses with high peak currents do not produce observable Elves, we investigate and compare the lightning activity occurring before these two types of events, in terms of both the number of lightning discharges detected by GLD360 and the peak currents of the preceding discharges. Our results, using data from GLD360, suggest that current pulses with peak currents above |120| kA tend to produce Elves nearly always, regardless of the preceding lightning activity. For current pulses with peak currents between |70| and |120| kA, the number of observed Elves might be affected by the preceding lightning activity, or is the result of the characteristics of the storm cells that produce the Elve.

Birthplace of ball lightning

Examples of ball lightning formation at high altitude near a linear lightning channel are considered. A photograph of ball lightning emerging from a linear lightning channel is shown. It is shown that the process of ball lightning formation lasts no more than 30 ms. A model of ball lightning formation due to the action of a magnetic field pulse of a linear lightning current on the ionized volume of space is described. A scheme has been proposed to explain a rare event - the gathering of ball lightning from sparks. Cases of the formation of ball lightning at a large distance from the site of a linear lightning strike, when energy was transferred through wires, are considered. It is noted that the process of formation of such ball lightning and their properties differ markedly from ball lightning appearing near the channel of linear lightning. This made it possible to distinguish these objects into a special type of ball lightning. A model of the process of formation of such ball lightning is described, according to which their core consists of ions flowing from the electrode of an air electrical capacitor (antenna, power line), and the shell material is dust particles. Cases of observation of objects with a size of 50 microns - 1 mm appearing during electrical discharges in water are considered. The analogy of these objects with miniature ball lightning is shown.

On Communication Tower Grounding Under Lightning Currents

On Communication Tower Grounding Under Lightning Currents

Результаты анализа грозовой деятельности на территории Республики Северная Осетия – Алания

The paper presents the results of thunderstorm activity study on the territory of the Republic of North Ossetia-Alania, and in particular, in the area of the all-season tourist complex “Mamison”. The analysis of the average annual factors of thunderstorm and lightning activity in the period from 2012 to 2022 in the warm period of time (May-September) according to the LS8000 thunderstorm direction finding system was performed. The estimation of the number of cloud-earth lightning ratios of positive and negative polarity is made, the influence of the orography of the terrain on the magnitude of lightning currents is investigated, the territorial features of the distribution of cloud-earth lightning currents of different polarity are determined. The resulting expression of the linear trend for the number of thunderstorms shows a decrease in thunderstorm activity in recent years in the study area.

Clarifying the mechanisms of edge glow generation in CFRP laminates exposed to simulated lightning currents

This study examines edge glow mechanisms of CFRP laminates exposed to simulated lightning current by performing direct electrical conduction tests. An impulse electric current, in accordance with SAE ARP 5412B, was applied to the laminates. Numerical simulations based on finite element analysis (FEA) were performed to clarify the voltage and temperature distributions of the CFRP laminates. The analytical results were validated using the experimentally obtained I–V characteristics and temperature responses. Resultingly, edge glow was observed in quasi-isotropic but not in unidirectional and cross-ply laminates. The edge glow was suppressed more in silicone oil than in air. When the edge glow did not occur, the numerical simulation results, I–V characteristics, and temperature response, exhibited good agreement with the experimentally obtained results. Contrary to Joule heating, potential differences of several hundred volts between each layer, which cause dielectric breakdown in the testing atmosphere, are the criterion for edge glow formation.

Jarak Penempatan Lightning Arrester sebagai Pelindung Transformator terhadap Tegangan Lebih pada Gardu Induk 150 Kv Harapan Baru

The substation is part of the electrical energy distribution system, therefore depending on its function it must be protected from disturbances that cause disruption to the distribution of electrical energy. One of the important equipment in a substation is a transformer, and the protection device used is a lightning rod. With its good characteristics, the arrester plays a role in bypassing lightning currents so that the equipment does not produce high overvoltages. The analysis results show that the maximum distance between the arrester and the transformer is 10.96 meters, while the installation distance in the field is 3.2 meters, so the arrester can still protect the transformer because it is still lower than the maximum distance. Allowed. After the arrester turns on for 9.54 μs, the voltage on the transformer will drop. And because the BIL of the transformer is 650 KV and the peak voltage reaches 751.3 kV at 300 μs, the arrester can still protect the transformer.

Effects of Approximating Recorded Lightning Currents With CIGRE Waveforms on Computed Fast-Front Overvoltages and Critical Lightning Currents Causing Flashover to Overhead Transmission Lines

This work investigates through simulations with the ATP-EMTP program the application of recorded lightning current waveforms to the estimation of fast-front overvoltages and critical lightning currents causing flashover to overhead transmission lines. Typical lines are evaluated with both horizontal (single-circuit) and vertical (double-circuit) phase configurations and AC voltage from 66 kV up to 765 kV. Backflashover as well as shielding failure flashover simulations were performed for several recorded first return-stroke current waveforms of negative downward lightning flashes, as reported in literature. Their approximations with the widely-used CIGRE lightning current waveform were also employed in simulations. CIGRE waveforms, considering the statistical distributions of the front time, maximum steepness, and time to half value, were used as well. A comparison between double-peak waveforms, composed of seven Heidler functions, and their CIGRE approximations is made. The latter generally yield conservative values of overvoltages and critical backflashover currents. The leader development models used for assessing the behavior of insulators and long air gaps under fast-front overvoltages are discussed regarding the criterion for the termination of leader propagation yielding withstand of line insulation.

The level of electrical resistance on electrolyte materials

Electricity causes a variety of well-known effects, such as lightning, static electricity, electromagnetic induction, and electric current. The presence of electricity can also generate and receive electromagnetic radiation such as radio waves. Electric current flowing from the voltage source through the wires to the light switch. Wires that carry electric current can be made of a variety of electrically conductive materials. Examples of electrical wire materials include aluminum, gold, silver, copper, and others. Electrical resistance is the property of an object or material to resist or restrain the flow of electric current. According to the principle of Ohm's law, the magnitude of the resistance of an electric circuit determines the amount of electric current flowing in the circuit for every voltage applied to the circuit. The amount of resistance of the conductor is determined by the length of the wire, the cross-sectional area and the type of resistance. Electric current, or dynamic electricity, is the flow that occurs due to a large electric charge. Electric charges move from one point to another, and these events occur successively per unit time. The international unit for electric current is the A or ampere. When writing the formula, the meaning of electric current is illustrated by the symbol I (current). We can use a tool called Basic meter to determine the amount of electric current. If you want to know the amount of voltage, you can use a voltmeter. The ammeter (ammeter) measures the strength of the electric current. The cross-sectional area shows the surface area of ​​the wire, while the length of the wire shows the length of the wire used. Copper is an electrical conductor in many classes of electrical cables. Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronic circuits and countless other electrical devices.

Comparison of soil modeling concerning physical factors: Application to transient analysis in wind turbines

This work analyzes the impact of the physical factors (frequency effect, water content, and porosity level) on the voltages developed along the wind turbine (WT) subjected to lightning strikes. The analysis is performed considering a realistic grounding system (GS) where the full-wave electromagnetic (ES) software FEKO/Altair Engineering® calculates the GS harmonic impedance (HI) for 100Hz to 10 MHz. For this purpose, six soil models [Visacro–Portela, Portela, Visacro–Alípio, Alípio–Visacro, Datsios–Mikropoulos, and Archie] and their transient responses are assessed. Comparisons are made with those assuming a frequency-constant (FC) soil at the dry condition. The GPR on the GS and the voltages on the tower base and nacelle are calculated using the software ATP® for the transient analysis. Results show a significant impact on HI with the physical factors, being remarkable at high frequencies and for high-resistive soils. Consequently, a notable decrease in the GPR peaks is seen compared with those with FC soils. These soil models and the lightning currents influence voltages at the nacelle and tower base. Results demonstrated that the Portela model predicts a more significant decrease in the voltages, and Datsios-Mikropoulos’s model provides closer responses to the FC soil. Increasing porosity yields larger peak values, and increasing water content produces lower voltages.

Transient Analysis and Prevention Measures of Lightning Strikes on Step-up Transformers in Wind Farms

Wind farms are mainly located in open and windy mountainous areas with complex climatic and topographic conditions, and the operation of equipment is inevitably affected by thunderstorms. In this paper, an electromagnetic transient analysis model for lightning strikes on collector lines is established with the use of the ATP-EMTP software. The overvoltage situation of step-up transformers subjected to lightning strikes on towers is analysed, and it is pointed out that existing lightning protection measures cannot effectively prevent the three-phase invasion caused by large current lightning, and a lightning protection strategy of installing a set of lightning arresters in the 35 kV bushing of the main transformer is proposed. A transformer trapezoidal equivalent circuit analysis model is established, and the effectiveness of the lightning protection measures are verified through simulation calculations, providing a technical reference for lightning protection in wind farms in multi-thunderstorm areas.

Parameters of the Initial Continuous Current of Negative Upward Lightning Measured at the Peissenberg Tower, Germany, From 1992 to 2022

In this article, we analyze the parameters of the initial continuous current (ICC) of the negative upward lightning measured at the Peissenberg Tower, Germany, from 1992 to 2022. A total of 54.9% of them were ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Only</sub> -flashes (without significant ICC-pulse), 24.0% of them were ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RS</sub> -flashes (with subsequent return stroke), 19.6% of them were ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> -flashes (with ICC-pulses > 2 kA), and 1.5% of them were ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bipolar</sub> -flashes (succeeded by a positive current component). The analysis revealed that the ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Only</sub> -flashes were the weakest ones, the ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> -flashes were the strongest ones, and the ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RS</sub> -flashes and the rare ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bipolar</sub> -flashes were in between. Out of the total of 204 measured ICCs, 16 (7.8%) of them exceeded the charge of 200 C, which represents the highest tolerable level according to the lightning protection standard IEC 62305-1. The strong ICC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> -flashes carried charges up to 454 C, being more than twice of this tolerable level.