Search results for " lightning"
showing 10 items of 13 documents
Transient behaviour of a “mixed” overhead-cable EHV line under lightning events
2009
Recently, in many countries have been undergone or are planning links with AC extra-high voltage (EHV) underground cables. Cable lines offer the possibility of a reduced environment impact and for this reason they are often the only alternative for the reinforcement or the expansion of power system accepted by public opinion. The coexistence of overhead and cable line in the so called ¿mixed¿ lines, however, raises several questions regarding their behaviour both in steady state and in transient. The purpose of this work is to investigate the transient behaviour of a mixed overhead-cable EHV line under lightning events, describing the effects of the following overvoltages on the system. The…
A Simultaneous Observation of Lightning by ASIM, Colombia-Lightning Mapping Array, GLM, and ISS-LIS
2021
The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS) provides optical radiances and images of lightning flashes in several spectral bands. This work presents a lightning flash simultaneously observed from space by ASIM, the Geostationary Lightning Mapper (GLM) and the Lightning Imaging Sensor on the International Space Station (ISS-LIS); and from ground by the Colombia-Lightning Mapping Array (Colombia-LMA). Volumetric weather radar provides reflectivity data to help to interpret the effects of the cloud particles on the observed optical features. We found that surges in radiance in the band at 777.4 nm appear to be related mostly with lightning processe…
On the distribution of lightning current among interconnected grounding systems in medium voltage grids
2018
This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations' grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1) two …
“Narrative Thunder; or, The Double Axes of Poetic Romanticism in ‘The LightningRod Man’”
2002
International audience
Un modello dinamico per la simulazione della ionizzazione di terreni non omogenei in presenza di elettrodi disperdenti elevate correnti impulsive
2008
La caratterizzazione elettromagnetica del comportamento dinamico di elettrodi interrati, disperdenti elevate correnti impulsive, costituisce uno degli aspetti primari nella progettazione di un sistema di protezione dalle fulminazioni atmosferiche (LPS). D’altra parte, elevate correnti impulsive possono causare l’insorgere di fenomeni di ionizzazione del terreno, nelle zone prossime agli elettrodi interrati, nei punti in cui il campo elettrico totale supera il valore critico. Modelli teorici e misure sperimentali correlano l’insorgere di variazioni di conducibilità del terreno in prossimità di elettrodi interrati interessati da elevate correnti impulsive al fenomeno della ionizzazione del te…
EMI Analysis in Electrical Drives under Lightning Surge Conditions
2012
In this paper, a complete model of a power drive system including the earth electrodes is proposed to evaluate electromagnetic conducted interference due to lightning pulses. Circuit model of a power drive system is joined with a full-wave approach for the simulation of the time behavior of the grounding system. The proposed model enables to predict the electromagnetic conducted interference generated in the power drive system when lightning conditions involve the earth electrodes.
Investigation of the skin lesions in lightning strike death
2021
Lightning strike-related deaths are unusual, and the victim bodies can present different lesions due to the different injury mechanisms associated with this event. Since the post mortem assessment can be challenging, the evaluation of the characteristics of the skin lesions becomes fundamental to reconstruct the event. Due to the paucity of literature on this topic, the authors report the case of a 59-year-old man found dead near his home after a thunderstorm. Initially considered a murder by gunshot, the autopsy revealed the typical lightning strike lesions, also known as Lichtenberg figures. The adequate interpretation of the autopsy data and the histological evidences allowed to reconstr…
Guidelines and Conceptual Design of the Grounding System of the DTT Experimental Facility
2022
The Divertor Tokamak Test (DTT) is an experimental nuclear fusion reactor currently under construction at the ENEA research center in Frascati and whose first plasma is expected in 2025. The present article shows the conceptual philosophy and the guidelines behind the design of the grounding system of the DTT. The article focuses on the main target of the grounding system and on the main technical standards to refer to for the design.
Finite-Difference Time-Domain Simulation of Towers Cascade Under Lightning Surge Conditions
2015
In this paper, the simulation of towers cascade under lightning surge conditions is presented. Finite-difference time-domain method is used to solve both the Maxwell's and telegraph equations. Maxwell's equations and the time-domain resistivity model of Darveniza are used to simulate the nonlinear behavior of the grounding system. Telegraph equations are used to describe the propagation in the overhead lines. Multiple ionizations, on different grounding electrodes belonging to various towers, can be implemented simultaneously, without making assumptions on the shape of the ionized areas.
Comparison of high‐speed optical observations of a lightning flash from space and the ground
2020
We analyze a nighttime negative cloud-to-ground lightning flash in Colombia observed from the ground with a high-speed camera at 5,000 images per second and from space by the Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS), the Lightning Imaging Sensor also on the ISS (ISS-LIS), and the Geostationary Lightning Mapper (GLM) on GOES-16. The space instruments measure the oxygen band at 777.4 nm, allowing for direct comparisons of measurements, and the ground-based camera observes in a wide visible band. After conversion to energy emitted at the cloud top, we find a good linear correspondence of the optical energies measured by the three space instruments, …