Search

Lightning strikes can cause equipment damage and power outages, so the distribution system's reliability in withstanding lightning strikes is crucial. This research paper presents a model that aims to optimise the configuration of a lightning protection system (LPS) in the power distribution system and minimise the System Average Interruption Frequency Index (SAIFI), a measure of reliability, and the associated cost investment. The proposed lightning electromagnetic transient model considers LPS factors such as feeder shielding, grounding design, and soil types, which affect critical current, flashover rates, SAIFI, and cost. A metaheuristic algorithm, PSOGSA, is used to obtain the optimal solution. The paper's main contribution is exploring grounding schemes and soil resistivity's impact on SAIFI. Using 4 grounding rods arranged in a straight line under the soil with 10 Ωm resistivity reduces grounding resistance and decreases SAIFI from 3.783 int./yr (no LPS) to 0.146 int./yr. Unshielded LPS has no significant effect on critical current for soil resistivity. Four test cases with different cost investments are considered, and numerical simulations are conducted. Shielded LPSs are more sensitive to grounding topologies and soil resistivities, wherein higher investment, with 10 Ωm soil resistivity, SAIFI decreases the most by 73.34%. In contrast, SAIFIs for 1 kΩm and 10 kΩm soil resistivities show minor decreases compared to SAIFIs with no LPS. The study emphasises the importance of considering soil resistivity and investment cost when selecting the optimal LPS configuration for distribution systems, as well as the significance of LPS selection in reducing interruptions to customers. [ABSTRACT FROM AUTHOR]

In this paper, we propose methods for the diagnosis of down conductor cables installed inside blades for the reliable operation of wind turbines. Utilizing the two synchronized drones equipped with X-ray devices to take X-ray images inside the blades, we propose deep learning methods for diagnosis based on X-ray images. The first method is the unsupervised deblurring method for blurry X-ray images that are generated by the drones. The key idea of the proposed method is to apply an image sharpening process to the latent space of the trained model using only blurry X-ray images. Through experiments using the X-ray images of blades, we show that the proposed method makes the outline of the down conductor cable clearer. As the second method, we propose an object detection-based method to provide fast and accurate object detection as the diagnosis. Given an X-ray image, we also propose a method to determine drone flight direction to enable drones to follow the down conductor cable. Through experiments, we show that our method has good performance in object detection (i.e., mAP of 98.21%) and classification (i.e., AUC of 0.9), and drone flight direction determination (i.e., AUC of 0.99).

This paper presents a novel approach to the simulation of the most common type of Cloud to Ground lightning strikes applied to a Photovoltaic farm with the view to validating its lightning protection system generally based on the electro geometric model as prescribed in the relevant international standards. It will be limited to the study of the electrostatic field distribution generated by a downward stepped leader progressing towards a large Photovoltaic Farm with a focus on its effect on the power electronics converters operating under lightning stress conditions. The Simulation was programmed using MATLAB’s Partial Differential Equations Toolbox based on the Finite Elements Analysis.

The global PV market has grown extensively for small- to large-scale systems. Inevitably, this leads to the increased development of PV technology. PV systems are intrinsically exposed to weather phenomena. One such phenomenon is lightning. Direct and indirect effects of lightning can cause damage to PV systems. However, lightning protection for PV systems is often neglected and existing standards for protection are underdeveloped. In this paper, previous work is analysed to understand the interaction between lightning and PV systems and to ascertain gaps in current knowledge thereof. Investigation of these aspects will ultimately assist in understanding lightning risk, protection system design and aid in the development of lightning protection standards for PV in the renewable energy industry. The article also presents a specific case study, outlining the lightning protection system of a 3200W photovoltaic plant on a farm. The work includes a thorough description of the lightning protection system, addresses issues related to the contamination of PV surfaces, and proposes practical measures to ensure the safe and reliable operation of photovoltaic systems under adverse weather conditions. The experimental results affirm the significance of implementing lightning protection systems to ensure the robust performance of solar power plants.

Introduction. The problem of estimating power losses in grounding wires with built-in fiber optic cable for overhead power lines of voltage class 330-750 kV is relevant, while it is obvious that the amount of losses depends on the chosen brand of wire. Problem. In the article, an analysis of the influence of the parameters of grounding wires on the amount of losses that occur in them in the normal mode of operation of the overhead power lines is carried out. Goal. The purpose of the work is to determine the criterion for the selection of grounding wires with a built-in optical fiber cable under the condition of increasing the energy efficiency of electricity transmission. Methodology. To calculate power losses in grounding wires, the methods of electromagnetic field theory were used, while taking into account the location of phase conductors on various types of towers of operating 330-750 kV overhead power lines and the possible current load of such lines. Results. The paper analyzed the dependence of losses in the grounding wires of the overhead power lines on the ratio of its active and reactive resistances, determined in which range of this ratio the losses will be close to the maximum. It is shown that the amount of specific power losses in the grounding wires of 330-750 kV overhead power lines in its normal operating modes can range from 1.6 kW/km for the 750 kV lines to hundreds of W/km for the 330 kV power lines. Originality. For the first time, it is recommended to use grounding wires with built-in fiber optic cable with running active resistance in the range of no more than 0.25 Ohm/km, which will minimize power losses and increase the energy efficiency of the 330-750 kV overhead power lines. Practical value. The obtained results can be applied at the stage of designing new or modernizing existing overhead power lines in order to reduce losses and increase the energy efficiency of lines.

Introduction. The problem of estimating power losses in grounding wires with built-in fiber optic cable for overhead power lines of voltage class 330-750 kV is relevant, while it is obvious that the amount of losses depends on the chosen brand of wire. Problem. In the article, an analysis of the influence of the parameters of grounding wires on the amount of losses that occur in them in the normal mode of operation of the overhead power lines is carried out. Goal. The purpose of the work is to determine the criterion for the selection of grounding wires with a built-in optical fiber cable under the condition of increasing the energy efficiency of electricity transmission. Methodology. To calculate power losses in grounding wires, the methods of electromagnetic field theory were used, while taking into account the location of phase conductors on various types of towers of operating 330-750 kV overhead power lines and the possible current load of such lines. Results. The paper analyzed the dependence of losses in the grounding wires of the overhead power lines on the ratio of its active and reactive resistances, determined in which range of this ratio the losses will be close to the maximum. It is shown that the amount of specific power losses in the grounding wires of 330-750 kV overhead power lines in its normal operating modes can range from 1.6 kW/km for the 750 kV lines to hundreds of W/km for the 330 kV power lines. Originality. For the first time, it is recommended to use grounding wires with built-in fiber optic cable with running active resistance in the range of no more than 0.25 Ohm/km, which will minimize power losses and increase the energy efficiency of the 330-750 kV overhead power lines. Practical value. The obtained results can be applied at the stage of designing new or modernizing existing overhead power lines in order to reduce losses and increase the energy efficiency of lines. [ABSTRACT FROM AUTHOR]

Lightning strikes can cause significant damage to critical infrastructure and pose a serious threat to public safety. To ensure the safety of facilities and investigate the causes of lightning accidents, we propose a cost-effective design method for a lightning current measuring instrument that uses a Rogowski coil and dual signal conditioning circuits to detect a wide range of lightning currents, ranging from hundreds of A to hundreds of kA. To implement the proposed lightning current measuring instrument, we design signal conditioning circuits and software capable of detecting and analyzing lightning currents from ±500 A to ±100 kA. By employing dual signal conditioning circuits, it offers the advantage of detecting a wide range of lightning currents compared to existing lightning current measuring instruments. The proposed instrument has the following features: First, the peak current, polarity, T 1 (front time), T 2 (time to half value), and Q (amount of energy of the lightning current) can be analyzed and measured with a fast sampling time of 380 ns. Second, it can distinguish whether a lightning current is induced or direct. Third, a built-in SD card is provided to save the detected lightning data. Finally, it provides Ethernet communication capability for remote monitoring. The performance of the proposed instrument is evaluated and validated by applying induced and direct lightning using a lightning current generator. [ABSTRACT FROM AUTHOR]

Air terminations must be strategically positioned at high-risk points to prevent lightning bypass. The likelihood of a direct lightning strike to points on a building can be evaluated using the dynamic electro-geometrical model (DEGM), which considers the geometric proximity of lightning orientation points in spaces around the structure to meshed points on the structure. This study evaluates the probability of a direct strike to simple structures and the maximum lightning currents that may strike the structure. The DEGM concept is applied within a defined lightning collection volume which saves computation time. Patterns that can lead to alternatives to DEGM are identified within the percentage strike probability for different heights of two cuboid structures. Three floating roof tanks of radii 20 m, 30 m, and 40 m are analysed. Four classes of lightning protection are applied for a simple building in compliance with the International Electrotechnical Commission guidelines using different heights of air termination rods for a gable roof structure. For class I, the lightning strike interception probability of the two rods is 99.96%, 99.90% for class II, 99.72% for class III, and 99.48% for class IV. Magnitude colour-coded 3D diagrams are presented to highlight strike probability and current variations.

Experimental and computer investigations were conducted into long-duration impulse current distribution in the lightning protection system, supplying network, and electrical installation of a test house that was equipped with household appliances. Long-duration impulse currents simulating lightning continuing currents were injected from the unique current generator into the test object. The current distributions in the elements of the test object were measured using current shunts, coaxial cables, and digital oscilloscopes, then they were modeled using the ATP-EMTP software package. The obtained results show a quite good agreement between the measured and computed current waveforms. The relationships between the values of currents at different points of the conductive installation are similar, as reported in previous studies on the fast-changing lightning return stroke component distribution, although the efficiency of the lightning protection system (LPS) is a few percent better for the long continuing current component in the case of a strongly conductive ground at the test site in Huta Poręby, part of the Rzeszów University of Technology. Due to the relatively low content of high-frequency components in the long continuing current spectrum, the waveshape of this lightning component is practically the same throughout the entire tested installation. [ABSTRACT FROM AUTHOR]

Lightning strikes can cause significant damage to critical infrastructure and pose a serious threat to public safety. To ensure the safety of facilities and investigate the causes of lightning accidents, we propose a cost-effective design method for a lightning current measuring instrument that uses a Rogowski coil and dual signal conditioning circuits to detect a wide range of lightning currents, ranging from hundreds of A to hundreds of kA. To implement the proposed lightning current measuring instrument, we design signal conditioning circuits and software capable of detecting and analyzing lightning currents from ±500 A to ±100 kA. By employing dual signal conditioning circuits, it offers the advantage of detecting a wide range of lightning currents compared to existing lightning current measuring instruments. The proposed instrument has the following features: First, the peak current, polarity, T1 (front time), T2 (time to half value), and Q (amount of energy of the lightning current) can be analyzed and measured with a fast sampling time of 380 ns. Second, it can distinguish whether a lightning current is induced or direct. Third, a built-in SD card is provided to save the detected lightning data. Finally, it provides Ethernet communication capability for remote monitoring. The performance of the proposed instrument is evaluated and validated by applying induced and direct lightning using a lightning current generator.

Air terminations must be strategically positioned at high-risk points to prevent lightning bypass. The likelihood of a direct lightning strike to points on a building can be evaluated using the dynamic electro-geometrical model (DEGM), which considers the geometric proximity of lightning orientation points in spaces around the structure to meshed points on the structure. This study evaluates the probability of a direct strike to simple structures and the maximum lightning currents that may strike the structure. The DEGM concept is applied within a defined lightning collection volume which saves computation time. Patterns that can lead to alternatives to DEGM are identified within the percentage strike probability for different heights of two cuboid structures. Three floating roof tanks of radii 20 m, 30 m, and 40 m are analysed. Four classes of lightning protection are applied for a simple building in compliance with the International Electrotechnical Commission guidelines using different heights of air termination rods for a gable roof structure. For class I, the lightning strike interception probability of the two rods is 99.96%, 99.90% for class II, 99.72% for class III, and 99.48% for class IV. Magnitude colour-coded 3D diagrams are presented to highlight strike probability and current variations. [ABSTRACT FROM AUTHOR]

The integration of renewable energy (RE) sources is increasing day by day because of their permanent existence and the limited quantities of fossil fuels. One of the most promising RE sources is photovoltaic (PV) technology, which is developing quickly in many countries worldwide. PV cells generate electricity by converting the sunlight to DC voltage. PV arrays are installed in outdoor areas and on the rooftops of homes to be directly subjected to the sun. Consequently, they are frequently subjected to lightning strikes, which may cause damage to PV arrays, service interruption, and additional cost for PV replacement. Therefore, an adequate lightning protection system (LPS) must be installed to protect the PV panels. In addition, the transient performance of PV panels during lightning strikes must be analyzed well. This paper presents a comprehensive review of the superior modeling methods of PV systems during lightning strikes. In addition, the paper displays the different platforms to simulate the transient effects of lightning strikes on PV systems. The lightning transient effects on PV arrays are studied based on the system modeling to assess the recommended LPS designs studied in the literature. The paper also gives some recommendations about the modeling methods and protection of PV systems during lightning strike. [ABSTRACT FROM AUTHOR]

The rolling sphere method for air termination placement on a structure is easy to apply, but it cannot be used to determine the probability of lightning strike to different points on the structure. The dynamic electro-geometrical model (DEGM) using numerical methods can be implemented to evaluate the interception efficiency of various air termination systems. The DEGM is implemented using the probability function of lightning current distribution which has a discontinuity at 20 kA. This study proposes a way to remove the discontinuity by the introduction of a continuous step function. The effectiveness of various centrally positioned air terminations on structures was also examined. Mesh air terminations are typically installed directly on the roof of protected structures. Using DEGM concept, result shows that lifting the mesh network by the penetration depth does not significantly improve the interception efficiency of the air termination network for a gable roof structure.

Experimental and computer investigations were conducted into long-duration impulse current distribution in the lightning protection system, supplying network, and electrical installation of a test house that was equipped with household appliances. Long-duration impulse currents simulating lightning continuing currents were injected from the unique current generator into the test object. The current distributions in the elements of the test object were measured using current shunts, coaxial cables, and digital oscilloscopes, then they were modeled using the ATP-EMTP software package. The obtained results show a quite good agreement between the measured and computed current waveforms. The relationships between the values of currents at different points of the conductive installation are similar, as reported in previous studies on the fast-changing lightning return stroke component distribution, although the efficiency of the lightning protection system (LPS) is a few percent better for the long continuing current component in the case of a strongly conductive ground at the test site in Huta Poręby, part of the Rzeszów University of Technology. Due to the relatively low content of high-frequency components in the long continuing current spectrum, the waveshape of this lightning component is practically the same throughout the entire tested installation.

• Several worldwide cases of lightning-related damages to monuments are reported. • Damages may occur due to lightning protection systems not conforming to IEC 62305. • Protection against lightning of historical monuments requires special attention. • Revisions to the risk management procedure of IEC 62305 are proposed. • A fractal-based LPS design for the Parthenon monument is introduced. A review on the lightning risk management and lightning protection of historical buildings and cultural heritage monuments is presented. Cases of lightning-related damages to historical monuments worldwide are presented with emphasis given to cases in Greece. Recorded incidents stress the need for an effective lightning protection system (LPS) design, ensuring sufficient protection of the monument against lightning, including its installations and contents, as well as persons. External LPS of several monuments and historical buildings worldwide are also presented. An external LPS has been designed for the Parthenon monument in Greece in accordance with IEC 62305. The LPS design has been evaluated based on a stochastic lightning attachment model. Revisions to the risk management of IEC 62305 with special focus on historical buildings and cultural heritage monuments are suggested. As this special category of structures is most commonly subject to constraints with respect to aesthetic intervention and construction, dedicated studies employing alternative methods for LPS design, based however on physical grounds, are required. [ABSTRACT FROM AUTHOR]

Multi-story buildings must be equipped with lightning protection to prevent direct lightning strikes. This study aims to evaluate the lightning protection system in the Khairun University rectorate building using the rolling ball method. The estimated hazard of lightning strikes based on PUIPP is 14, so the Khairun University rectorate building needs SPP. With a height of 27 meters and an efficiency value of SPP E = 0.22. Thus, the Khairun University rectorate building is not known for its level of SPP needs. The rectorate building of Khairun University with the rolling ball method has a radius of protection known from the efficiency table for the value of 0.22 does not exist. Thus, the calculation of the radius of the protected area cannot be used. The ground resistance in the Khairun University rectorate building does not meet the PUIL 2000 standard with a standard value of not more than 5 Ohms.

The rolling sphere method for air termination placement on a structure is easy to apply, but it cannot be used to determine the probability of lightning strike to different points on the structure. The dynamic electro-geometrical model (DEGM) using numerical methods can be implemented to evaluate the interception efficiency of various air termination systems. The DEGM is implemented using the probability function of lightning current distribution which has a discontinuity at 20 kA. This study proposes a way to remove the discontinuity by the introduction of a continuous step function. The effectiveness of various centrally positioned air terminations on structures was also examined. Mesh air terminations are typically installed directly on the roof of protected structures. Using DEGM concept, result shows that lifting the mesh network by the penetration depth does not significantly improve the interception efficiency of the air termination network for a gable roof structure. [ABSTRACT FROM AUTHOR]

This article proposed a computer-based simulation approach to estimate touch and step voltages due to a lightning strike at a mass rapid transit railway station. A purely resistive circuit model of a station lightning protection, and earthing & bonding system is formed in MATLAB/Simulink with Yaek Nonthaburi 1 passenger station of MRT purple line in Bangkok, Thailand as a case study. The simulation investigated the consequence of a lightning strike at four different locations on the roof of the station and examined whether or not the lightning protection system met the standard requirements. The results showed the touch voltages, step voltages and body currents in a steady state together with the impact on the human body standing in the station. The simulation can guarantee the effectiveness of the proposed model, and also proved that the lightning protection system of the station is able to conform to the standard and there is no harm for the passenger in the station. [ABSTRACT FROM AUTHOR]

Lightning strikes happens in a fraction of time, where they can transfer huge amounts of charge and high currents in a single strike. The chances for a structure to be struck by lightning increases as the height increases; thus, tall structures are more prone to lightning. Despite the existing lightning protection systems available for wind turbine blades, there are still many cases reported due to the fact of damage caused by lightning strike. Owing to that, the present work introduces a new approach for a lightning protection system for wind turbine blades where preliminary investigations were done using Analysis Systems (ANSYS) Workbench. Two models were developed: one with a conventional type down conductor system and the other with a hybrid conductor system. The recorded findings have been compared and discussed, where it was found that the hybrid conductor system may provide alternative protection from lightning for wind turbine blades. [ABSTRACT FROM AUTHOR]

In this study, the lightning protection system and grounding system of one plant of the petrochemical industry were investigated, evaluated, and improved. The methods used in this study were rolling sphere and angle protection methods. The grounding system of the building under study was modeled and simulated using ATP/EMTP (Alternative Transient Program/Electromagnetic Transient Program) software. The results show that the external lightning protection system of the prilling tower studied does not adhere to IEC 62305 and IEC 1024-1-1 standards. Moreover, the grounding configuration of the DCS building was not appropriate for protecting sensitive equipment inside. Lightning causes an enormous potential difference between lightning ground rods in the grounding system. Additionally, disabling the existing surge protective device (SPD) causes an increase in the magnitude of Ground Potential Rise at the DCS building. Improvement of the lightning protection system of the prilling tower and DCS building on Plant 1 of this petrochemical company as well as some other recommendations for improvements are proposed. This paper also shows evidence that external lightning protection, internal lightning protection, and the grounding system need to be connected to make an exemplary lightning protection system.

This study was aimed at identifying the causes of continuous failures, fires, and explosions of electrical and electronic systems in educational facilities that result from lightning, which occurs frequently during the summer. The study is also aimed at suggesting prevention measures for such damage. The installation status and problems of lightning protection systems (LPSs) were examined by analyzing the damage compensation data of the Korea Institute of Educational Facility Safety, a questionnaire and field survey, and related laws. A total of 49,989 educational facilities responded to the questionnaire. The survey indicated that out of all the educational facilities, 21% had external LPSs, 6.2% had internal LPSs, 4% had both internal and external LPSs, and only 2.5% had installed bonding in addition to internal and external LPSs. The LPSs were not installed properly because the heights of most educational facilities are less than 20 m although the Building Act stipulates that LPSs should be installed in buildings with a height of 20 m or more. Furthermore, periodic inspections and checkups were not performed because the Electric Utility Act does not apply to LPSs. However, starting in January 2021, the installation and management of LPSs will be conducted in accordance with the Korean Electric Equipment Regulation, which includes the standards for LPSs. A design using a field survey must be performed prior to the installation of LPSs. Based on the survey, an estimate should be calculated, and the design, construction, and supervision should be performed.

Lightning strikes happens in a fraction of time, where they can transfer huge amounts of charge and high currents in a single strike. The chances for a structure to be struck by lightning increases as the height increases; thus, tall structures are more prone to lightning. Despite the existing lightning protection systems available for wind turbine blades, there are still many cases reported due to the fact of damage caused by lightning strike. Owing to that, the present work introduces a new approach for a lightning protection system for wind turbine blades where preliminary investigations were done using Analysis Systems (ANSYS) Workbench. Two models were developed: one with a conventional type down conductor system and the other with a hybrid conductor system. The recorded findings have been compared and discussed, where it was found that the hybrid conductor system may provide alternative protection from lightning for wind turbine blades.

The leader progression model (LPM) is employed to investigate the shielding system performance of high-voltage substations against direct lightning strokes in the presence of substation instruments. The substation is simulated in detail for high accurate calculation of the shielding failure rate. Almost all of the apparatuses are modeled as fictitious charges in the stepwise simulations of LPM. The charge simulation method is used for finding the electrical field during the lightning movement. The probability of upward leader propagation is considered from all apparatuses. For more practical simulation, the environmental conditions are also included in simulations. The investigations are implemented on a test case and a practical high-voltage substation. The results are compared to those of the electrogeometric model. It is very likely that the results of this paper better simulate reality because lots of parameters have been taken into account. The results reveal that the presence of substation instruments increases the striking distance and the SF since they attract the lightning moving down near the substation. [ABSTRACT FROM PUBLISHER]

This paper introduces a heterogeneous CPU+GPU co-processing implementation of the method of moments (MoM) for broadband full-wave electromagnetic analysis of grid-like spatial shields for protecting structures against LEMP effects. Broadband capacity of the approach is achieved through supporting MoM by adaptive frequency sampling and implicit rational interpolation of the observed quantity via Stoer-Bulirsch algorithm. The overall application performance is increased by hardware acceleration, i.e., by employing CPU+GPU co-processing. Sample numerical results for a lightning protection system directly hit by lightning show that reliable rational interpolation can be done at substantially reduced computational effort compared to that of conventional uniform sampling, and the CPU+GPU co-processing offers additional noticeable speedup over the CPU single-thread implementation of the method. [ABSTRACT FROM AUTHOR]

Lightning is a natural occurring phenomenon having a very high voltage and current. Building protection from the effect of lightning stroke is one of the most important features. Lightning flash, nature changes with increasing the clearance between the ground structure and the cloud. Providing proper protection to the building, Frankling rod/Lightning air terminal is an essential element to receive the lightning flashes in order to make sure the protection of building. In this paper a down scaled building with four lightning rods has been chosen to see how the lightning rods with different air gap and view of the building perform, in lightning flash. The building is tested with three different views which are front, back and side views. The lightning rods provided different air gaps/clearance between the plain and the top plate. Single stage impulse generator is used. A voltage up to 90 kV is applied to analyze the lightning flash receiving ability of lightning rods. Through experimental work the lightning flash receiving ability is studied in detail for three views of the down scaled building. [ABSTRACT FROM AUTHOR]

Lightning protection testing laboratory is an important testing institution, it plays the role of checking lightning protection system for safety performance, analyzing data, evaluating result, and issuing the report to society. In order to promote safety operation and scientific management of the lightning test instruments, the configuration characteristics and management status of the laboratory instruments was were analyzed, and the safe use and scientific management of instruments was were explored. It which mainly includes strengthening the management system, standardize standardizing the purchasing process, improve improving the file management, improve improving the use system, intensifying the users, operating skill. [ABSTRACT FROM AUTHOR]

Open air experiments were conducted of impulse current distribution in the lightning protection system, supplying cable and electrical installation of a test house equipped with electrical and electronic household appliances. Impulse currents were injected from the generator into the installation. Current distributions in elements of tested system were measured with multi-channel electro-optical system. To verify the experimental results the simulations of surge current in the test house modeled in ATP-EMTP were conducted. The obtained results show a good agreement between measured and numerically simulated currents and significant influence of frequency dependent parameters of the test house elements on both the amplitude and the shape of current waveforms. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper utilizes CDEGS software to calculate the transient ground potential rise (GPR) in a commercial building, with a base of 39\ \m\ \times 13\ \m and a height of 21 m, during direct lightning strokes. The influences of soil resistivity, location of the lightning strike point, and wave shape of the lightning current on the transient GPRs of three scenarios for the building are analyzed. Such scenarios within the building include the following: 1) devices are grounded independently; 2) devices are grounded via vertical ground electrodes that are connected to each down conductor fixed on the outside of the building; and 3) devices are grounded via a ring ground electrode that is sited around the periphery of the building. The results show that the ring ground electrode provides effective lightning protection for the building under lightning and, therefore, is recommended. [ABSTRACT FROM AUTHOR]

The critical electric field of soil ionisation is very important for the performance of grounding system and spatial distribution of electromagnetic field in the soil when lightning directly strikes the lightning protection system. To estimate the critical electric field in the soil, a tangential electric field method is proposed based on the electromagnetic field analysis presented in this study. With this method, the instant moment when the soil ionisation occurs is obtained by examining the tangential component of horizontal electric field. According to the maximum electric field in soil without soil ionisation for every moment, the soil critical electric field could be estimated. In addition, the critical electric fields for four different types of soil reported in the literature are estimated with the tangential electric field method, yielding satisfactory agreement. [ABSTRACT FROM AUTHOR]