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In this paper, we present and discuss simultaneous records of current and wideband electric field waveforms at 380 km distance from the strike point associated with an upward bipolar flash initiated from the Säntis Tower. The flash contains 23 negative strokes and one positive stroke. The height of the ionospheric reflection for the positive pulse was inferred to be about 94.9 km, a value which is...
In this paper, we present a semi-analytical simplified approach based on the ray tracing method to estimate radiated electric fields associated with lightning return strokes, taking into account ionospheric reflections. The field transfer function at each frequency and each grazing angle is determined by applying the generalized Snell's law of refraction, and the antenna radiation pattern concept...
Lightning location systems (LLSs) are often used to obtain parameters of lightning flashes. However, the imperfect detection efficiency (DE) of these systems affects the accuracy of the results. In this paper, we focus on the effects of the imperfect DE on the probability distribution of interstroke intervals. Two DE models are considered here: one dependent on the peak amplitude of return stroke...
In this paper, we present a methodology for estimating the protection levels of critical equipment against IEMI. We apply the method to a wireless communication infrastructure, but it can be applied to any critical infrastructure. The required protection levels that need to be implemented are determined by analyzing the susceptibility of the victim, and the threat level associated with a specific...
The standard lightning waveforms used for the testing of aircraft are based on downward lightning. However, there is evidence suggesting that lightning to aircraft is different from negative downward lightning. Also, carbon fiber composite materials are being used extensively in wind turbines and aircraft which comprise small, sensitive electronics as part of avionics and control systems. In this...
We identify typical banking information technology (IT) equipment that is exposed and susceptible to IEMI threats. Using 3D models of the most plausible attack scenarios, we estimate the electric field transfer functions between an electric field source and the equipment under attack, using an incident plane wave, and we illustrate the application of the obtained transfer function for the calculation...
The project STRUCTURES, funded by the European Union, started in July 2012 to study problems related to the emerging threats of electromagnetic attacks to critical infrastructures. Partners of the team have worked to list possible threats, identify the main characteristics of the critical infrastructures our way of living depends on, test current protection strategies with different simulation and...
Lightning is one the major sources of electromagnetic interferences. Multisensor networks known as lightning location systems (LLS) are widely used to detect and locate different types of lightning discharges (see, e.g., Cummins and Murphy, IEEE Trans. EMC, 51 (3), pp. 499–518, 2009). Modern LLS use different detection techniques such as the Time-of-Arrival (ToA), Magnetic Direction Finding (MDF)...
In this paper, we report the results of wind turbine grounding system impedance measurements performed at the Mont-Crosin wind park in Switzerland. Experiments were carried out twice: (1) when only the construction of the wind turbine foundation had been completed, and (2) once the installation of the rest of the wind turbine was finished: tower, nacelle and blades. The transient grounding impedance...
In this paper we present a numerical analysis of lightning current distribution in the conductive elements of a wind turbine blade. They include lightning down conductor, blades spar caps made of carbon fiber reinforced polymers (CFRP) and protective copper mesh placed on the spar caps. The problem is solved in frequency domain by using the finite element method. Anisotropic electrical conductivity...
In this paper, we present an analysis of the initiation of upward lightning flashes for the Gaisberg and the Säntis Towers. The results are compared with previous studies. It is found that the majority of upward lightning discharges from both towers are initiated without any preceding lightning activity. We show also that the results of the presented studies on the initiation of upward flashes from...
Intentional electromagnetic interference (IEMI) poses an increasing threat to electronic systems, as the technology and expertise required to construct a disruptive source become more readily available. Localizing the IEMI source is an additional way to fight against these attacks. In this paper, a possible scenario of an IEMI attack is described and the challenges of localising the IEMI source in...
This paper describes a cost-efficient Intentional EMI Detection system and gives a brief overview of the identification and location system being developed as part of the STRUCTURES project.
We present a general methodology to investigate potential effects on the statistical assessment of lightning current parameters due to bandwidth limitation in measuring systems. The proposed methodology is illustrated starting from pure log-normal distributions for current peak and risetime and assuming different upper frequency bandwidths for the measuring system (250 kHz, 500 kHz and 1 MHz). It...
Lightning electromagnetic pulse (LEMP) is a severe threat to sensitive electronic devices installed in buildings. In order to protect these devices from LEMP effects, the evaluation of the electromagnetic fields inside the building is required. Numerous studies have been devoted to the analysis of these fields stemming from direct and indirect lightning strikes. In this paper, using a GPGPU-based,...
We present in this paper an analysis of bursts of fast pulses in current waveforms associated with positive lightning flashes of type 1 recorded on the Säntis Tower in Switzerland. Type-1 flashes are characterized by the presence of a large unipolar current pulse with characteristics similar to those reported by Berger and co-workers. Several milliseconds to several tens of milliseconds prior to the...
The distribution of lightning flash density over large areas depends on many factors. In this paper, we analyze one of them, namely the terrain elevation. Some previous studies suggest that the lightning flash density decreases above a certain altitude. We show that this conclusion could be affected by the used method of analysis and we suggest two improved methods. The lightning flash density distribution...
The deployed instrumentation at the Säntis Tower in Switzerland to measure lightning currents and lightning current derivatives is presented. During the first 18 months of operation, the measurement system successfully recorded more than 200 flashes to the tower. 15% of the recorded flashes (namely 30) were of positive polarity, and 1.5% (3 flashes) were bipolar. We also present a summary of the statistical...
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