Browse Topic: Lightning protection

Items (113)

Electrically Non-Conductive Ladder Fall Protection

TBMG-3619403/01/2020

NASA’s Kennedy Space Center developed an electrically non-conductive ladder fall protection system for the Launch Complex (LC) 39B lightning towers. The towers include a 100-foot fiberglass mast at the top of the tower structure. The fiberglass masts insulate the metallic tower structure from the lightning strike protection system that is housed at the top of the fiberglass masts.

S400 Copper Media Interface Characteristics Over Extended Distances

AS5643/1A (Current)07/09/2019

This SAE Aerospace Standard (AS) establishes guidelines for the use of IEEE-1394-2008 Beta (formerly IEEE-1394b) as a data bus network in military and aerospace vehicles. It encompasses the data bus cable and its interface electronics for a system utilizing S400 over copper medium over extended lengths. This document contains extensions/restrictions to “off-the-shelf” IEEE-1394 standards, and assumes that the reader already has a working knowledge of IEEE-1394. This document does not identify specific environmental requirements (electromagnetic compatibility, temperature, vibration, etc.); such requirements will be vehicle-specific and even LRU-specific. However, the hardware requirements and examples contained herein do address many of the environmental conditions that military and aerospace vehicles may experience. One should refer to the appropriate sections of MIL-STD-461E for their particular LRU, and utilize handbooks such as MIL-HDBK-454A and MIL-HDBK-5400 for guidance. This

AS-1A Avionic Networks Committee

Streamlining EMC Solutions for Avionics Interfaces

TBMG-3377302/01/2019

Streamlining EMC Solutions for Avionics Interfaces

19AERP02_0402/01/2019

Lightning strikes to jet airliners are common - about once every 1000 flight hours. The DO-160G standard, Environmental Conditions and Test Procedures for Airborne Equipment, is a standard for the environmental testing of avionics hardware. Many airplane manufacturers specify DO-160G Section 22, lightning induced transient susceptibility, as a requirement for critical systems like guidance, radars, communications, engine control, and heat and air controls. Aircraft fuselage, wing and tail flight controls, wing tips, fin tips, engine nacelles, and landing gear are the areas most likely to be hit by lightning strikes. Modern aircraft are designed with fly by wire systems for flight controls. Fly by wire means that inputs from either flight control computers or pilot manual inputs are transmitted electrically to a servomotor, which controls flight control actuators. Communication interfaces for these flight control systems can be implemented on an RS-485 physical layer. Communication

Aircraft Lightning Zone

ARP5414B (Current)12/05/2018

This SAE Aerospace Recommended Practice (ARP) defines lightning strike zones and provides guidelines for locating them on particular aircraft, together with examples. The zone definitions and location guidelines described herein are applicable to Parts 23, 25, 27, and 29 aircraft. The zone location guidelines and examples are representative of in-flight lightning exposures.

AE-2 Lightning Committee

Sequential/Simultaneous Multi-Metallized Nanocomposites (S2M2N)

TBMG-2798712/01/2017

NASA Langley Research Center has developed a method to create Sequential/Simultaneous Multi-Metallized Nanocomposites (S2M2N) via supercritical fluid (SCF) sequential or simultaneous multi-metal infusion. The SCF infusion process provides deep impregnation of metal nanoparticles into a variety of materials, including those with challenging topographies and complex structures. The resulting multi-metallized nanocomposites can possess high electrical conductivity, permittivity, permeability, wear resistance/anti-penetrant, and radiation shielding along with high toughness.

Thermoplastic Fuselage Demonstrator

TBMG-2766110/01/2017

Porcher Industries Badinières, France +33 (0)4 74 43 10 10

Lightning Protection and Detection System

TBMG-2615501/01/2017

NASA’s Langley Research Center has developed a sensor technology for structural health monitoring on composite aircraft surfaces. When conventional aircraft are struck by lightning, the result can range from no damage to serious damage requiring extensive repairs that can take the airplane out of service for an extended period of time. The SansEC technology is a proven wireless sensing platform capable of measuring the electrical impedance of physical matter in proximity to the sensor based on a change in its resonance response. The sensor also exhibits a unique characteristic to disperse the lightning strike current to help mitigate lightning damage. In this application, an array of SansEC sensors will cover a selective area of the aircraft surface, providing both mitigation and damage sensing.

Electric Field Quantitative Measurement System and Method

TBMG-2613901/01/2017

NASA Langley Research Center’s Electric Field Imaging (EFI) system is the only noncontact method capable of quantitatively measuring the magnitude and direction of electrostatic fields in near- and far-field applications. Based on low-cost, commercially available components, the EFI system uses measurement of very-low-current, human-safe electric fields to construct a three-dimensional image of objects and people based on their dielectric properties. This platform technology, originally developed for measurement of the efficacy of electrical shielding around cables, could be optimized for a variety of applications, including medical imaging, security and detection, weather and natural disaster prediction, and nondestructive evaluation of composites and insulators. The EFI system has the potential to offer a lower-cost, portable, and safer alternative to the imaging systems currently used in these applications.

Aerospace - Lightning Effects on Hydraulic Transport Elements on Aircraft

AIR6185 (Current)08/28/2015

This SAE Aerospace Information Report (AIR) describes hydraulic system design and installation to minimize the effects of lightning, especially when the aircraft structure is composite. Techniques for effective electrical bonding, hydraulic system lightning protection, and lightning protection verification techniques are discussed.

A-6A1 Commercial Aircraft Committee

NASA Launch Pads Protected Against Lightning-Induced Power Surges

TBMG-20668

10/01/2014

Circuit protection components Littelfuse Chicago, IL 773-628-1000

Aerospace & Defense Technology: February 2014

14AERP0202/03/2014

Thermal simulation and testing of expanded metal foils for lightning protection With the implementation of major aircraft structures fabricated from carbon fiber reinforced plastic materials, lightning protection has become a more complicated issue for designers and engineers to solve. Electronics take charge Digital controls are handling more engine control tasks on a wider range of aircraft.

Aircraft Structure Paint Thickness and Lightning Swept Stroke Damages

2013-01-213509/17/2013

During its flight an aircraft can be struck by lightning and the induced high current will require a highly conductive airframe skin structure in order for it to propagate through with minimum damage. However an aircraft skin is generally coated with paint and the airframer does not always have control on the paint thickness. Paint thickness generates heightened concerns for lightning strike on aircraft, mainly because most of coatings dedicated to that purpose are non-conductive. Using insulating material or non-conductive coating with certain thickness may contribute to or increase damage inflicted by the swept stroke lightning energy, even on metallic structures Due to its high relative permittivity, a non-conductive paint or coating on a fuselage skin surface will contribute to slow down the lightning current propagation through structure. With this comes the risk of increasing heat that will favor structural damage and possible melt through. The correlation between paint thickness

Moupfouma, Fidele

Electromagnetic Protection Hazards on Composite versus Metallic Aircraft

2013-01-215709/17/2013

The lightning represents a fundamental threat to the proper operation of aircraft systems. For aircraft protection, Electromagnetic Compatibility requires conductive structure that will provide among all, electromagnetic shielding and protection from HIRF and atmospheric electricity threat. The interaction of lightning with aircraft structure, and the coupling of induced energy with harnesses and systems inside the airframe, is a complex subject mainly for composite aircraft. The immunity of systems is governed by their susceptibility to radiated or conducted electromagnetic energy. The driving mechanism of such susceptibility to lightning energy is the exposure to the changing magnetic field inside the aircraft and IR voltage produced by the flow of current through the structural resistance of the aircraft. The amplitude of such magnetic field and IR voltage is related to the shielding effectiveness of the aircraft skin (wiremesh, composite conductivity). However, it is also known

Moupfouma, Fidele, Klim, Zdzislaw, Skorek, Adam

Lightning Requirements: Where They Come From and How to Analyze Their Impact

2012-01-214910/22/2012

Many avionics and aircraft equipment manufacturers use DO-160 [Ref. 1] Section 22 to test their equipment for indirect effects of lightning without understanding why they are testing to specific values. Many aircraft manufacturers struggle with determining the level of indirect lightning that will be acceptable for their vehicle and what level of requirements they need to pass down to the avionics and aircraft equipment manufacturers. Organizations like SAE and RTCA, Inc. work to collect data on lightning and spend countless hours assimilating the information and developing documents to help engineers use the information. They struggle with knowing what data is pertinent and how it will be received and used by the engineering community. This paper walks through the process of how the lightning levels are developed, how the levels get selected for a particular application, and how to use this information to perform an analysis of the survivability of a specific circuit in an electronic

Harrington, James

Software Creates and Analyzes Lightning Protection Solutions for Wind Turbines

TBMG-1465809/01/2012

Highvoltage.dk is a Danish consulting engineering firm with expertise in lightning protection and high-voltage engineering. The company, founded in 2005, tackles complex problems such as general high-voltage design engineering for the power industry, lightning protection concepts and findings for wind turbines, and high-voltage material tests. The engineers at Highvoltage.dk are experienced users of numerical analysis tools to simulate magnetic and electric fields, current distribution, and lightning attachment points.

An Advanced Circuit Protection Approach for RF Interfaces

TBMG-1228812/01/2011

One aspect that sets circuit protection for radio frequency (RF) apart from other types of applications is the range of frequencies in which RF circuits operate. With abbreviated clock cycles, the transition time of the data leaves little room for error. Transitions must be clean and reliable to ensure the integrity of the data and interface. Circuit protection characteristics such as capacitance become important in terms of their effect on these high-frequency signals and it often complicates the design.

Data Acquisition System Monitors Lightning Strikes

TBMG-1191511/01/2011

Genesis HighSpeed data acquisition system and Perception software HBM Marlboro, MA 508-624-4500 www.hbm.com

Probability Assessment of the Fuel Tank Structural Feature Failures

2011-01-251810/18/2011

The paper provides an approach to establish compliance with current regulatory standards applicable to lightning protection of the fuel tank structure for Non-Fault Tolerant Feature Failures (NFTFF) through a numerical probability assessment. The proposed procedure is using the criteria defined in the FAA Policy Guidance for fuel tank structural lightning protection and is aligned with the regulatory path described as petitioning for an exemption. Failure modes of structural components for which fault tolerance has been shown to be impractical need to be addressed and the overall likelihood of fuel vapour ignition due to these failure modes must be shown to be extremely improbable. In order to accomplish this, the quantitative assessment of the overall probability of fuel vapour ignition is performed, along with all relevant data to support the probabilities determined for the purpose of this analysis. The relevant non-fault tolerant structural design areas that may contribute to

Klim, Zdzislaw H., Skorek, Adam W.

Lightning Monitoring System Helps Protect Shuttle

TBMG-792705/01/2010

Genesis HighSpeed data acquisition products HBM Marlborough, MA 800-578-4260 www.hbm.com/highspeed

MIL-STD-1553 Physical Layer for Time-Triggered Networks

2009-01-314711/10/2009

Time Triggered networking technologies such as TTP (Time Triggered Protocol) are beginning to be used in critical aerospace applications such as flight controls. While TTP provides stringent specifications for determinism and fault tolerance, it does not define a physical layer. TTP's “de facto” physical layer, RS-485, includes shortcomings in a number of areas. These include a relatively low minimum transmitter voltage, low receiver threshold, along with a lack of specificity in a number of areas. The latter include bus signal levels, transmitter zero-crossing distortion and receiver zero-crossing tolerance, isolation method, terminal output noise, common mode and noise rejection, and input impedance. MIL-STD-1553, which has been deployed in flight and mission critical military applications for decades, defines a highly proven and robust physical layer. This paper presents MIL-STD-1553's physical layer as a candidate for use with TTP.

Glass, Mike

Aircraft Lightning Direct Effects Certification

ARP5577 (Current)03/26/2008

This document provides guidance for a means of showing compliance with regulations for protection against lightning direct effects for aircraft of conventional design, as well as for those involving advanced composite structures or other new technologies. This guidance also applies to those aspects of aircraft systems and components not addressed in the regulations covering the protection of electrical/electronic systems (for example, FAR/JAR xx.1316) or fuel systems (for example, xx.954). The guidance provided in this document applies to initial designs as well as modifications.

AE-2 Lightning Committee

Flight Line Grounding and Bonding of Aircraft

ARP4043B (Current)10/09/2007

This ARP provides the rationale and theory of charges being present on aircraft while on the ground. The necessary implementation of safety practices are explained and defined.

AE-4 Electromagnetic Compatibility (EMC) Committee

Certification of Aircraft Electrical/Electronic Systems for the Indirect Effects of Lightning

ARP5413A (Current)

03/21/2007

AE-2 Lightning Committee

Characterization of Aircraft Electrostatic Charging/Discharging Effects and the Influence of Aircraft Skin Conductivity

2006-01-150704/03/2006

During an aircraft flight, water droplets, snow or precipitation will impact the fuselage and the wing surfaces, and develop static charges on the structure. Because of composite materials, those charging particles can produce potential differences between surfaces of different aircraft zones. The transients generated by the discharge can couple into onboard electronic/electrical systems and cause no found faults or upsets. Electrostatic Discharge (ESD) phenomenon resulting from corona effect can generate very high electric field that can couple with wiring bundles and generate communications disruption during flight. ESD effects have to be properly addressed during an aircraft design, as are Lightning and HIRF. This paper presents some theoretical considerations and experimental data based on full aircraft ESD ground tests at Bombardier facilities in Mirabel (Montreal).

Moupfouma, Fidele, Bae, Nami

Certification of Aircraft Electrical/Electronic Systems for the Indirect Effects of Lightning

ARP5413 (Historical)03/24/2006

This SAE Aerospace Recommended Practice (ARP) provides guidance for a means of showing compliance with the regulations for hazards caused by the lightning environment to electrical/electronic systems installed either on or within aircraft. Equipment hazards addressed include those due to indirect effects on equipment and its associated wiring that is mounted on the aircraft exterior as well as indirect effects on equipment and its associated wiring located within the aircraft interior. This document applies to new aircraft and equipment designs, modifications of existing aircraft or equipment, and applications of existing (off the shelf) equipment on new aircraft. NOTE: This ARP does not address direct effects such as burning, eroding, blasting, of aircraft structure nor does it address fuel ignition hazards (see related reading material in 2.3 of this document). This ARP does not address lightning zoning methods or lightning test requirements, methods, and techniques. Coverings

AE-2 Lightning Committee

Study of Lightning Effects in Aircraft

2004-01-323611/16/2004

Lightning is a high voltage and high current phenomenon and it originates by build up of electrical charge in the air or, more commonly, in clouds. It is constituted of an electric current peak of short duration (0,5 ms) and high intensity (200 kA), followed by a low intensity (400 A) but high duration (1s) periods. The lightning effects in aircraft can be divided in two groups: direct effects (physical effects such as melting, rupture, damage of surfaces and structures due to conduction of lightning current or high power magnetic force) and indirect effects (electromagnetic fields generating levels of transient voltage and current on interconnecting wiring and cable leads within the equipment circuits eventually damaging internal components). The objective of this work is present and discuss the lightning effects and, subsequently, possible lightning protection applied to aircrafts by establishing adequate conductive paths for lightning current to flow through the aircraft structure

Baldacim, Sandro Aparecido, Cristofani, Nivaldo, Santos, Carlos do Nascimento, Lautenschlager, José Rui

Current Parameters of Lightning Discharges Measured at the Peissenberg Telecommunication Tower

2001-01-287909/11/2001

In 1992 new lightning measurements were started at the Peissenberg telecommunication tower. The tower is situated in the south of Germany nearby Munich. All strikes to the tower were upward initiated ground-to-cloud flashes except of one event identified as negative downward initiated cloud-to-ground flash. The majority of the ground-to-cloud flashes were of negative polarity lowering negative charge to ground. Based on more than 100 negative ground-to-cloud flashes updated statistics of current parameters are given distinguishing between different current components, such as impulse and continuing currents. The statistics include the current peak values, the maximum current derivatives and the full widths on half value of the current derivatives. Further, the meteorological condition and the striking probability are examined.

Heidler, F., Zischank, W., Wiesinger, J.

Precipitation-Static (P-Static) Overview of Composite Aircraft

2001-01-293309/11/2001

Aircraft charging due to p-static results from two atmospheric conditions: 1) the vehicle’s presence in a thunderstorm, and 2) the triboelectric charging (frictional) caused by neutral snow, rain, or dust particle bombardment of the vehicle frontal surface. Both charging mechanisms can lead to p-static interference by the following mechanisms of charge redistribution: 1) corona discharges from sharp-edged extremities, 2) streamer discharges on dielectric surfaces, and 3) arc over between electrically isolated or intermittently grounded metallic sections. Corona discharges have spectral energy primarily in the LF through HF region but can have potentially significant energy levels in the VHF/UHF bands. Streamer noise is caused by charge buildup on non-conductive vehicle frontal areas such as radomes and windshields. The spectral energy content of streamer discharges extends beyond the UHF band; but the noise amplitude is low and the potential for RF interference is only a threat if the

Thornell, Jerry W.

NFPA-780 (1997) Standard for the Installation of Lightning Protection Systems: Transitioning from an Outdated Concept

2001-01-292109/11/2001

The National Fire Protection Association NFPA-780 Standard for the Installation of Lightning Protection Systems is the de facto lightning protection document in the USA. Special interest groups seeking to force scientifically unsubstantiated air terminals into NFPA-780 have coerced under threat of litigation the NFPA Standards Council to withhold the Version 2000 Upgrade of NFPA-780. This present state of paralysis exists despite membership approval of the Version 2000 Upgrade in accord with all the NFPA by-laws. More recently the Standards Council publicized its intent to (perhaps) withdraw NFPA-780 entirely. As a consensus document NFPA-780 represents minimum protection standards and contains some errors and omissions. The purpose of this paper is to discuss some of the NFPA-780 (1997) shortcomings and to summarize other lightning protection documents already peer-reviewed and in the literature. These alternative lightning protection guidelines may assist the specifying architect and

Kithil, Richard

Small Shelters and Safety from Lightning

2001-01-289609/11/2001

Small open shelters are common on athletic fields, golf courses, parks, roadside picnic areas, schoolyards, and elsewhere. Many of these shelters are built to protect against rain or sun, not lightning. What can be done to minimize risk/maximize safety for people inside them under direct and indirect lightning strike conditions? Although there is no such thing as a lightning-proof small outdoor shelter, a properly designed and installed lightning protection system may make a difference. Sometimes the difference is between life and death.

Kithil, Richard, Rakov, Vladimir

Waveform Comparisons Between Qualification Data and Aircraft Measurements

2001-01-291709/11/2001

Lightning induced current and voltage pulses are defined in international standards as arising from three distinct coupling mechanisms: capacitive, inductive and resistive. These mechanisms at their simplest give rise to distinct characteristics in the induced wave-shapes relative to the lightning current pulse that caused them. It has long been the practice to decide from a particular induced wave-shape, which was the likely induction mechanism, and compare it in terms of peak amplitude only with the relevant qualification test waveform. This approach fails to take account of the fact that almost all induced waveforms are actually a sum of two or all of the coupling mechanisms, that the coupling is not simple but gives rise to much more complex wave-shapes than the qualification standards would imply, and that there are other critical parameters apart from the peak amplitude. It may also disguise the effect of possible building/rig resonances in test results. In this paper the authors

Jones, C. C. R., Powell, Shawn, Gallagher, Joe

Frequency Domain Analysis for the Prediction of Lightning Indirect Effects and Comparison to Measured Data from Two Composite Test Articles

2001-01-290609/11/2001

A lightning indirect effects analysis of a conductor over graphite composite structure was performed using a frequency domain analysis. An internal Boeing analysis code, EM_Model, was used to predict and model test data from two graphite composite test articles. The first was a simple graphite panel with an aluminum tube placed at various heights above the panel. The aluminum tube is representative of either hydraulic or fuel lines, or cable bundle shields. The second test article was the outboard section of a graphite wing-box with two aluminum tubes internal to the structure. A series of access panels in the wing skin provided a source of aperture coupling in addition to the diffusion currents. Both tests made low level CW (LLCW) measurements of the tube transfer function and were compared to model results with good agreement.

Dabelstein, Donald

Use of Modeling to Design Lightning Protection on Launch Vehicle

2001-01-290009/11/2001

This paper focuses on advanced electromagnetic computational tools used for designing protection against the indirect lightning effects on launch vehicles. The launcher design has to integrate lightning requirements determined by a lightning risk and risk coupling analysis. Lightning currents couple with the launcher avionics mainly through cables running externally along the booster stages where they are the most exposed. These cables are generally protected by ducts which are made either of conductive or dielectric material. In the last case,. If the duct is dielectric, the cable bundles have to be protected by braided overshielding. When it is made of aluminium alloy, it is obviously attempting to use the duct itself as overshielding. A cable duct is a complex mechanical assembly. Its electromagnetic attenuation is more difficult to control than that of a braided overshielding. In order to provide quick reliable advice, electromagnetic coupling of the cable duct bundles is

Schaffar, André, Fargeot, Sylvie, Rennesson, Yves

Application of the Finite Difference Time Domain Code EMA3D to the Modeling of Indirect Lightning Effects in a Composite Panel and Wing Box

2001-01-291109/11/2001

The Finite Difference Time Domain (FDTD) method (as implemented in the commercial software package EMA3D) is used to model indirect lightning effects in a composite three bladed panel and a composite wing-box. The analysis is compared with low level continuous wave (LLCW) tests performed in the Boeing Lightning Effects Laboratory. Measured data include transfer functions for currents induced on metal tubing interior to the three-bladed-panel and wing-box. The thin wire and thin plate formalisms provided in EMA3D are used to model the composite surfaces and metallic conductors such as pipes in the wing-box. The wing-box is simulated both with and without apertures. The modeling results showed excellent agreement with measurements over a broad frequency range demonstrating the usefulness of FDTD as a predictive tool for lightning frequencies.

Lenning, Frank E., Rimbey, Peter R.

Probabilities of Catastrophe in Lightning Hazard Assessments

2001-01-287709/11/2001

The airworthiness certification authorities specify overall probability levels for catastrophic and less severe effects on aircraft and their occupants. In lightning standards concerning threat levels and zoning for lightning attachments we speak of high and low probabilities. But, despite the certification authority’s overall figure, only one attempt has been made to interpret what that figure means for lightning protection. That one attempt was made under the EC funded FULMEN programme to estimate the degree of accuracy needed in the process of aircraft lightning attachment zoning. Without some figures, how do we know how good our designs have to be. Furthermore, as the number of flight-safety critical systems on our aircraft increases, how does the probability of failure of each change to ensure the overall figure remains the same? There are many figures we do not have, because lightning is too unpredictable an event, because we have too few measurements of the “real” lightning that

Jones, C. C. R., Rowse, D., Odam, G. A. M.

Leader Characteristics in Natural and Altitude Triggered Lightning Discharges

2001-01-287109/11/2001

Characteristics of the electric field changes produced by stepped and dart-stepped leaders in natural negative cloud-to-ground (CG) lightning discharges and stepped leaders in altitude triggered lightning discharges have been analyzed by using data from broadband slow antenna system with 0.08 μs time resolution in Guangzhou area, Southeastern China. It has been found that the characteristic parameters of leader pulses in artificially triggered lightning discharges are a little different from that in natural negative lightning discharges, although the discharge processes and statistic features of the pulses are similar in two cases.

Xiushu Qie, Qilin Zhang Ye Yu

Electrical Strength of Ultra-Long Air Gaps

2001-01-289809/11/2001

Some experimental results on discharge development in ultra-long air gaps (breakdown voltages, parameters of the leader stage) are presented. The obtained data are compared to available data on breakdown of long air gaps under positive switching pulses with critical time-to-crest. Existing empirical and theoretical formulae for calculation of sparkover voltage of rod-to-plane air gaps are reviewed. Electrical strength of ultra-long air gaps is considered based on general analysis of physical processes in leader stage of spark discharge. The electrical strength has been thus expressed in the given paper via some characteristic stabilization electric field for each spatial scale. As predicted here, the electrical strength along the lightning development path may decrease down to 3÷10 kV/m.

Syssoev, Vladimir S., Shcherbakov, Yuri V.

On the Modelling of Field-to-line Coupling Inside a Lightning Struck-Aircraft

2001-01-289109/11/2001

This paper discusses the features of different field-to-line coupling simulation models to be used for the transient analysis of the EM induced effects of the direct lightning interaction with aircraft. The choice of one model is suggested by the quasi-magnetostatic nature of the lightning interaction problems, which generate numerical inaccuracy in the calculation of the electric field solution inside the computational domain. It is demonstrated that the use of the field-to-line coupling model based on the use of the magnetic field components allows to avoid numerical inaccuracy.

Sarto, Maria Sabrina, Scarlatti, Alberto

Lightning Protection: Experimental Approach and Solutions for Large Sensitive Systems - Example of a Nuclear Power Plant -

2001-01-292209/11/2001

This document describes the unclassified part of the lightning protection studies for a video control system. The study was held during September 1994 at Cruas Nuclear Power Plant (F-07). Positive improvements were seen immediately and long term benefits have been reinforced by continued protection. The studies were conducted with a new EMC (Electromagnetic Compatibility) concept: “Zero Method”. This concept uses an accessible and easy process to control the industrial electromagnetic interference from radio, cellular phones and lightning effects. The adopted solutions improve personnel and facility safety and provide a cost effective solution.

Soleil, Daniel, Alcaras, Alain

New Investigations of the Mechanisms of Lightning Strike to Radomes Part I : Experimental Study in High Voltage Laboratory

2001-01-288309/11/2001

The main purpose of the experiments described here is the analysis of the mechanisms of radome protection with lightning diverters of various types and sizes. A high voltage arrangement and associated diagnostics have been implemented to perform a quantitative study of the inception and propagation mechanisms of the corona and leader discharges that precede the final breakdown. It is shown that ambient humidity plays a significant role on the discharge process and that the nature of the discharge initiated from the strip is very different depending on the strip type. Segmented strips are more likely to allow energetic discharges to propagate from an internal antenna leading to radome puncture.

Ulmann, A., Brechet, P., Bondiou-Clergerie, A., Delannoy, A., Lalande, P., Blanchet, P., Laroche, P., Bocherens, E., Bacchiega, G. L., Gallimberti, I.

Lightning Protection Design of a Renewable Energy Hybrid-System Without Power Mains Connection

2001-01-293209/11/2001

In the year 2000 a direct lightning strike to the hybrid-system without power mains connection VATALI on the Greek island Crete results in the destruction and damage of some mechanical and electrical components. The hybrid-system VATALI was not lightning protected at that time. The hardware damage costs are approx. 60,000 €. The exposed site of the hybrid-system on top of a mountain was and still is the reason for a high risk of lightning strikes. Also in the future further lightning strikes have to be taken into consideration. In the paper a fundamental lightning protection design concept for renewable energy hybrid-systems without power mains connection and protection measures against direct strikes and overvoltages are shown in detail. The design concept was realized exemplarily for the hybrid-system VATALI. The hardware costs for the protection measures were about 15,000 €. About 50% of the costs are due to protection measures against direct strikes, 50% are due to overvoltage

KernF, Alexander, Krichel, Frank, Mueller, Klaus-Peter

Influence of the Rod Height and Lightning Polarity on the Protection Zone

2001-01-289709/11/2001

Presented in this paper is a method to calculate the Franklin rod protection zone, through mathematical equations by considering the Franklin rod height and lightning stroke polarity impacts on striking distance[1]. The method was developed and analyzed for different cases with varied rod heights, and for positive and negative polarity. The calculated results of the protection zone were compared to the laboratory measured outcomes of several protected objects with varied heights.

Grzybowski, S.

The Numerical Simulation of the Effects of Lightning Current Arcs at the Attachment Point

2001-01-287309/11/2001

The damages and destructions on materials at the attachment point of an lightning arc are mainly caused by thermal effects. Pressure effects and shock waves which occur due to the high temperatures are mostly the consequence of these thermal processes. The calculation and prediction of the heating processes lead to a better understanding of the damage mechanisms. This allows the assessment and the design of materials and lightning protection components. The paper presents calculations for different materials and a critical comparison with some laboratory measurements. Investigated materials are several metals (Cu, Al, steel) on the one hand and carbon fibre composite (CFC) on the other hand. These materials differ in their electrical and thermal material parameters and in their reactions to the lightning arc stress. It was the aim of the calculations to determine the development of temperature distribution up to critical temperatures.

Brocke, Ralph, Noack, Friedhelm, Reichert, Frank, Schoenau, Jens, Zischank, Wolfgang

New Methodology for Determining the Extension of Lightning Swept Stroke Zones on Airborne Vehicles

2001-01-287609/11/2001

During the lightning strike to an aircraft in flight, the lightning channel gets deformed in the aerodynamic flow and displaced along the aircraft, a so-called swept stroke. To be able to correctly determine the different levels of hazards on an aircraft (zoning), the physical behaviour of the lightning swept stroke must be understood. This behavour is outlined in the paper and a model for numerical simulations of the swept stroke process is presented together with examples of 3D simulations. The overall objective to include this model within the frame of an operational code for zoning computations is discussed in conclusion.

Larsson, Anders, Bondiou-Clergerie, Anne, Lalande, Philippe, Delannoy, Alain, Dupraz, Sylvain

A Comparison of the Prediction of Lightning Indirect Effects Using 2-D Analytical Tools with Measured Data from Two Composite Test Fixtures

2001-01-290409/11/2001

A comparison was done of the prediction capabilities for lightning indirect effects of two two-dimensional (2-D) computer codes using two graphite structural test fixtures. The two codes evaluated were an internal Boeing Method-of-Moments code and a commercially available Boundary Element method code. The codes were compared against each other and against test data. The purpose was to evaluate the prediction capabilities of both codes for use in predicting lightning indirect effects on internal components of graphite structure. Since 2-D codes are much easier to use than 3-D codes, they could be widely used in trade studies and design evaluations for lightning indirect effects protection of composite aircraft. The first code, REDIST, is a Method-of-Moments code developed in the 1980’s for use on the B-2. The REDIST code has short run times and is somewhat easier to use than the second code that was investigated. The second code examined, Oersted, is a Boundary Element method code and

Melander, Barbara, Gibbs, John, Sojka, Richard

Indirect Lightning Prediction Codes

2001-01-289309/11/2001

Codes have been written that allow designers to predict lightning indirect effects on aircraft wiring and structural elements. As a cost saving alternative to aircraft level testing, the codes will be used to calculate actual transient levels (ATL) on aircraft wiring with the purpose of verifying system lightning protection certification compliance by analysis. The code suite employs a CAD feature to enter the problem geometry. Additional user inputs include electrical characteristics of an airframe, excitation of the airframe with lightning attachments, and computation and display of the electrical response of any electrical member of the airframe versus time. The time series for an electrical response is calculated using inverse Laplace transforms of pole-zero terms fitted to the spectral response of the chosen element. In all cases tested to date, very few pole-zero terms are needed compared to the number of frequency samples required for the equivalent accuracy using standard

Nachamkin, Jack, Brigante, Joseph

ALISDAR: An Automatic Lightning System Detection and Recording

2001-01-291909/11/2001

In the framework of an EC (European Community) project EM-HAZ (Electromagnetic Hazard), an Automatic Lightning System Detection And Recording (ALISDAR) has been developed. Electrical and magnetic field measurements are the best way to characterize the lightning strike to aircraft. A finite difference time domain (FDTD) method is used to estimate the lightning current from E and H field measurements. The severity and the location of the lightning strike could be used to optimize the maintenance operations. The best location in terms of cost for the ALISDAR sensors is a dummy window. The validation of the ALISDAR system is planned through two laboratory experiments.

Lalande, P., Blanchet, P., Laroche, P., Gineste, P. N., Basso-Cochard, B., Flourens, F., Ulmann, A., Dimnet, P.

Lightning Protection Design Methodology for a Very Large Non Rigid Airship

2001-01-293109/11/2001

Successful lightning protection design is important for the CargoLifter CL 160 large non-rigid transport airship. Non-rigid airships, like balloons, have few hard structures so alternative means need to be designed to collect and conduct lightning currents. The helium lifting gas ionizes at one third the field intensity required for air so spark formation in ambient electric fields is more likely to originate inside a helium filled envelope than in the air outside of it. Protection development is being accomplished by a combination of high voltage strike attachment tests on scale models, and numerical analyses of electric fields.

Eberle, Martin, Marcordes, Ralf, Jaeger, Dieter, Perala, Rodney A., Plumer, Andy, Schwarz, Harald

Responses of Lightning Rods to Nearby Lightning

2001-01-290709/11/2001

In an effort to determine the effectiveness of the sharp tipped lightning rods widely used in the U.S., we carried out a competition between sharp and blunt rods to determine which was preferentially struck by lightning. Over the past eight years, 12 blunt rods participated in cloud-to-ground discharges while none of the nearby rods with sharp tips were struck. Our analysis suggests that the emissions of point discharges from the tips of sharp rods associated with the rapid decrease of the electric field strength around the tips combine to make sharp rods poorer receptors for lightning than are moderately blunt rods.

Moore, Charles B., Aulich, Graydon, Rison, William

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