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In order to retrieve the lightning attachment points, 12 sensors distributed over the aircraft continuously monitor the local electric and magnetic field. The selection of the number and positions of the sensors is described in [4]. The ILDAS is triggered by sudden changes in the field strength in the aircraft. The sensors then determine the local magnetic fields, retaining pre-and post-trigger data over the time span of about 1 s. After landing, the data are compared with possible field distributions derived for a number of current path scenarios [3], and the most likely entry and exit regions are determined.

The In-flight Lightning Damage Assessment System ILDAS has been presented in EMC Europe in 2012. ILDAS can determine the lightning current distribution on an aircraft with high resolution in time and amplitude. Later the system was extended and included two x-ray detectors to measure the high-energy radiation that is generated in thunderstorms and by lightning proper. It has been flown for many times now. The paper presents a few selected data.

A novel sensor for the detection of the lightning current through the fuselage of an aircraft has been tested on an A320 aircraft. An accurate method-of-moment model of the window edge provided reliable calibration of the sensor for external fields. The data have been analyzed and the good performance of the sensor in sensitivity and bandwidth is demonstrated.

A novel sensor is described for the detection of the lightning current through the fuselage of an aircraft. The sensor relies on the penetration of the magnetic field through fuselage openings and can be embedded in a window inside the aircraft. The sensor combines good sensitivity with sufficient bandwidth to record the lightning transient current. Guidelines for the position are derived from a mathematical analysis for a circular window.

In a recent paper (G. Bargboer and A. P. J. van Deursen, IEEE Trans. Electromagn. Compat., vol. 52, no. 3, pp. 684-90, Aug. 2010) we dealt with current injection measurements to test the lightning protection system of a newly built pharmaceutical plant. In a tentative extrapolation, the measurements were extrapolated to actual lightning. Here, we extend the model and calculate the response of the installation on lightning currents and include resonances in the cable trays and test cables contained in it. It turned out that suspension rods between roof support and cable tray were indispensable to suppress the resonances. The time dependence of the present results and the earlier simplified model given in differ greatly, but the amplitudes of induced voltages appear to be of the same order of magnitude.

A newly built pharmaceutical plant has been investigated by measurements. Currents of 0.3 kA were injected in the lightning protection grid on the roof. Inside the building, test cables of 100 m length followed a path typical for cables belonging to the installation. We measured induced cable currents and voltages. A reduced model of the building incorporated most of the designed current paths. Measurements and model showed that the roof steel skeleton carried about 80% of the current and the intended lightning conductors 20%. The calculated current through a cable support was larger than measured. This is explained by also considering a nearby nonintended conductor. For three types of cables, we determined the transfer impedances. The measurements and model have been combined and extrapolated to actual lightning.

A 2 MV lightning surge generator is a powerful source of interference, in particular when the voltage waveform is chopped by a shorting spark gap. We not only do need to protect the sensitive diagnostic electronic equipment that operates on small signals, but we also should guarantee its flawless operation during the discharge. The paper discusses the setup, the EMC measures taken, and the results of verification measurements. Some typical results obtained in the research with this instrument will be shown as well.

Large-scale tests at the new Harbor Railway Line in The Netherlands asked for a dedicated measuring system for all currents at eight cross sections of the railway. The differentiating/integrating measurement scheme with adapted versions of Rogowski coils and special integrators fulfilled the requirements with respect to accuracy, bandwidth, electromagnetic compatibility, life-time, and environmental constraints. Three types of current sensors were developed; their air-core guaranteed linearity over the full current range up to 20 kA. Most importantly, the sensors allowed unimpeded rail transport. The paper discusses the sensors, the rationale, and tests, as well as the integrators. The system has been successfully employed, before and after the large-scale tests, in Luxembourg and Portugal. A few out of much data gathered show the broad applicability of the system.

The effect of a nearby U-shaped metal cabinet panel on the inductive common-mode coupling of a printed circuit board (PCB) is calculated in a two-dimensional (2-D) model by Schwarz-Christoffel (SC) transformations for doubly connected regions. Such an open metal cabinet can significantly reduce the mutual inductance between the microstrip lines on the PCB and the common-mode circuit if the cabinet is properly connected. But it may also increase the coupling for balanced pairs of tracks, in particular where the coupling for a single track varies strongly with position. Details of the SC approach are presented. The SC results agree with those of a static method of moments approach, but also clearly indicate the accuracy limits of the latter method.

Radio base stations are often mounted on towers of power transmission lines. They are usually powered from the low-voltage network through an isolating transformer, to separate the high- and low-voltage networks. The isolating transformer ensures security at customers' premises in the case of nearby power faults and particularly in case of lightning striking, which is a frequent cause of flashover of the high-voltage insulators and a subsequent phase-to-ground fault. To optimize such protection, a better understanding of the current distribution to the ground in the initial phase of the lightning striking is required. This work presents a computer simulation method and its results for the lightning current distribution between the sky wires, grounding systems, and power cable network. What is of special concern is the part of the lightning current that might be led into the metal-shielded distribution cable network. A rigorous electromagnetic modeling approach was applied for the analysis of the grounding effects in a network of coated and uncoated low- and medium-voltage cables. The analysis was then applied to a practical case.

Low-voltage (LV) applications mounted on high-voltage (HV) towers may pose a safety problem in the low voltage network when a flashover occurs over the high-voltage insulators. To study the effects experimentally, a 150 kV system was made available. On a high voltage tower carrying a cellular phone base station, one phase insulator was shorted to the tower. A current of about 200 A was injected into that phase at a large distance. We measured the current distribution and the relevant voltages in the low voltage net. The experimental current data agree with EMTP calculations. Appropriate measures to guarantee safety for persons and electronic equipment are discussed.

Common-mode (CM) currents on cables attached to printed circuit boards of various complexity have been measured. The boards have a continuous ground plane, with tracks on both sides. The experimental results are compared to calculations with a transmission-line (TL) model. Expressions for the coupling parameters in the TL model have been derived with conformal transformations and the method of moments. Measurements up to 1 GHz agree with the TL model, showing that this model can be used as a tool for an early EMC analysis during the lay-out and routing of a board.

Metallic conduits provide mechanical support for cables, and may also protect the cables against interference caused by currents induced by external electromagnetic fields. The conduit transfer impedance Z/sub t/ then is a good measure for the provided protection. We studied Z/sub t/ by means of conformal transformations and of the method of moments in a quasistatic, two-dimensional (2-D) approach. Practical U-, H-, L-, and T-shaped conduits are discussed. Conformal transformations provide simple engineering expressions for the mutual inductance part of Z/sub t/ for cable positions inside the conduit. The method of moments formulation results in useful approximations for the crossover frequencies in Z/sub t/ between DC and high frequency. Measurements on U-shaped conduits confirm the calculations.

The introduction of 25 kV a.c. traction in the Dutch railway system required a careful study of the compatibility with existing 1500 V d.c. traction and with other systems in the vicinity of the railway. Over the last decade, a number of studies have been carried out, using specially developed measurement systems and methods of analysis. The present paper describes a newly developed Poynting sensor that builds on the earlier developed differentiating/integrating measurements system. Measurements on the railway power system with current injection at e.g. 60 and 48 Hz will be discussed as well.

In the EU FP6 project ILDAS a prototype In-flight Lightning Damage Assessment System is developed for passenger aircraft and helicopter. The project aims to localize the attachment and the severity of the strokes during flight to assist maintenance. A database of events will be constructed to substantiate requirements for aircraft lightning immunity. Inductive magnetic field sensors are put at various positions on the aircraft. The sensors are followed by passive/active integrators to deal with the large dynamic range and bandwidth, and by high speed data conversion/storage. The paper focuses on design and tests of three types of sensors.

Armored installation cables are often intended to be buried in the soil. The benefits of such armor for frequencies up to a few MHz are generally known. We determined the transmission parameters of such a cable with a network analyzer, and measured the shielding effectiveness of the armor up to 1 GHz in a reverberation chamber. A solid shield coaxial cable with a small hole acted as calibration.

The lightning protection of a pharmaceutical plant has been tested by current-injection on the structure. The study aims at two goals: 1) proof of safety by scaling the currents and voltage to lightning realistic values and 2) a comparison between measurements and a Method of Moments calculation. We measured the current distribution near the source and the induced currents and voltages in test cables. The cables and their 100 m long path were representative for the actual installation. By necessity the model is simplified, because of the large number of conductors, intended and unintended, and the uncertainty of their interconnection. The calculated currents are a factor of 3 larger than measured. © 2009 IEEE.

Power systems often use coated and/or uncoated metallic sheathed cables for medium and low voltage distribution. The metallic sheaths of such cables are connecte to the grounding systems and may have significant grounding effects. In case of uncoated metallic sheathed cables they act as extended grounding electrodes while coated cables connect different grounding systems at transformer stations and customer premises. This usually improves the grounding conditions at the source transformer station but potentially dangerous voltages might be transferred to other locations. This paper analyses the lightning current distribution between the local grounding system, stoked by lightning, and connected cable metal sheaths. It is shown that after the first tens of microseconds local grounding system loses its function and cables take away nearly all, lightning current

The lightning protection of various industrial installations has been investigated by injecting current of smaller amplitudes. Large deviations of the intended current distribution and high values of induced voltages have been observed. Local measures can remedy the deficiencies.

Commercial passenger aircraft are on average struck by lightning once a year. The in-flight lightning strike damage assessment system (ILDAS) project is to develop and validate a prototype of a system capable of in-flight measurement of the current waveform and reconstruction of the path of lightning current. This paper discusses the various magnetic sensors, their rationale and some tests. Inductive sensors require an integrator in the signal conditioning. Much attention has been paid to the passive integrator, which is the first integrator stage preliminarily responsible for EMC.

Cellular phone base stations are often placed in the poles of power transmission lines. We consider the case when such base stations are powered from the low-voltage network. Of special concern is the current that might be led through the cable metallic shields to other customers' premises in case of lightning stroke, which is a frequent cause of flashover of the high-voltage insulators and a subsequent phase to ground fault. This paper presents an analysis in the frequency domain of the lightning current distribution between the earth wires, grounding systems and power cable network, in case of lightning stroke at the tower. The models and the analysis are applied to a practical case

This paper describes the consequences of a fault in a medium voltage network on the grounding systems at the LV-side. To study the current distribution and to verify the models, we deliberately introduced one phase to ground faults in the 10 kV floating MV network. The selected site was the end of a 2 km long buried MV cable feeding a small group of houses; the soil there had a high resistivity. The fault current was 127 A. The current distribution and the relevant voltages were measured at several positions in MV and LV net. We compare the results for a TT and a quasi-TN earthing system in the houses, also taking the telecom cable into account. The distribution of the fault current over the MV cable, measured at another MV station at 2.2 km distance, are in agreement with calculations, based on a model which includes the contact of the lead shield of the MV cable with the ground. Current and voltage data are compared with calculations. Eindhoven University of Technology and the Dutch power distribution company NUON, carry out a joint research project on global earthing. In this project we treat different faults and various interference sources e.g. lightning and switching events together.

Conduits of various shapes offer good electromagnetic protection to cables placed inside. As measure of protection, the transfer impedance has been studied; in the frequency range of interest the current adjusts between the low and high frequency distribution in the conduit. Quasistatic two-dimensional calculations are based on the method of moments and on conformal transformations. Practical U, H, L and T shapes are studied mostly. Engineering equations directly give the dominant parts of the transfer impedance for various cable positions inside non-magnetic conduits. Measurements on U conduits confirmed the models.

Since 1991, NUON has applied a TN system for their LV network, low voltage clients are then no longer required to have a separate ground electrode. To guarantee safety for LV clients not only faults in the LV network, but also ground faults in HV or MV grids should be considered, since they may cause large touch voltages in the LV network. A particularly interesting example is a LV system in a HV tower, as is the case with a mobile phone base station. A safety problem may occur in the low voltage network after a flashover of the HV insulators. A fraction of the 50 Hz current will flow into the LV grid. We studied the problem both with an experiment and simulations. In this paper we give a detailed description of our measurements. A new guideline to protect persons and electronic equipment is discussed.

Low voltage applications mounted on high voltage towers may pose a safety problem in the low voltage network when a flashover occurs over the high-voltage insulators. To study the effects experimentally, a 150 kV system was made available. On a high voltage tower carrying a cellular phone base station, one phase insulator was shorted to the tower. A current of about 200 A was injected into that phase at a large distance. The authors measured the current distribution and the relevant voltages in the low voltage network. A experimental data agree with EMTP calculations. Appropriate measures to guarantee safety for persons and electronic equipment are discussed.

The classical lightning conductor, which must prevent fire, has to have a sufficiently small resistance. An analogous condition can be formulated for the new challenge: the protection of sensitive electronics against lightning. In this case, the so-called transfer impedance, which gives the interference voltages across a sensitive input per ampere lightning current, must be made small. The arguments for this approach are described. A theoretical description is available and practical experience has been built up over the years, also in high-voltage (HV) research and in power engineering measurements in the field. This approach was used to greatly improve the lightning protection of several installations: a marine radio station, the peripheral equipment of a nuclear power plant, and an electronic siren for a nationwide public warning system. Detailed investigations were requested by our contract partners, together with suggestions for economically acceptable improvements that could be carried out in reasonable time. Later, the correctness of the renovations had to be demonstrated. In the validation measurements, we injected currents into the installation or into relevant parts thereof. The current waveform was chosen fast enough so that inductive effects determined the current distribution. At present, lightning position and tracking system (LPATS) data on lightning strikes near the marine radio station and the nuclear power plant are available to verify the effectiveness of the protection. After our improvements no more damage was reported.

Metallic trays and conduits protect bundles of cables in electrotechnical installations by diversion of interference currents. The relevant parameter is the conduit transfer impedance Z/sub i/. Conformal transformations yield the inductive part M of Z/sub i/ for conduits with noncontacting covers. Analytical approximations for M agree well with measurements.