Farnborough

Farnborough International Airshow 2016

11th – 15th July, Farnborough UK. This year EMA will be attending the Farnborough International Airshow, one of the world’s premier airshows. Along with our European partners Ingegneria Dei Sistemi, we will be showcasing our electromagnetic modeling and simulation tools for the aircraft and satellite industries, as well as one of our UAV’s configured to perform EMC/EMI assessments.

The EMA and IDS booth will be hosted at the Regione Lazio – Lazio Innova stand, Hall 1, Booth A118, where we will also be holding a series of workshops covering the uses of electromagnetic modeling and simulation:

Date: Tuesday 12th
Time: 15.45 – 16.30
Title: The Expanding Role of Electromagnetic Simulation in Aircraft Type Certification
Description: 
New regulations and new aerospace materials drive up the cost and complexity of type certification. Advances in simulation capability and validation accuracy have greatly increased the use of electromagnetic simulation as a method of compliance to combat the rise in cost and program schedules. In this presentation, we describe the new role for these tools along with how they can be used to enhance testing to reduce overall program cost, duration and risk.

Date: Wednesday 13th
Time: 15.00 – 15.45
Title: New Electromagnetic Tools for New Space
Description: 
There is a growing interest in human spaceflight, which will require levels of safety and reliability akin to commercial air travel. Concurrently, there are dramatic shifts in space programs toward lower cost, reusability and higher production rates. As a result, electromagnetic requirements for space are shifting away from rigid rules to an approach where everything must be justified and verified carefully in an extremely short period of time. In this presentation, we describe an emerging class of simulation tools that provide these new space teams with suite of validated tools to quickly and accurately design safe and low cost systems with a high degree of confidence.

Date: Thursday 14th
Time: 15.00 – 15.45
Title: Advanced Electromagnetic Modelling for Space application
Description: 
The seminar will discuss the benefits of high fidelity EM modelling in standard applications such as antenna siting on satellites. Further, we will deal with non-conventional EMC (electromagnetic compatibility) problems such as the modelling of antennas mounted on re-entry vehicles in the presence of plasma cloud and analysis of the interaction of antennas with plasma plume emitted by ion thrusters.
This seminar is based on the experiences gained by IDS in more than 30 years as a consulting company participating in satellite programs such as Sicral, Lisa pathfinder, SAC-D, Oceansat, Galileo, SmallGeo and Cosmo SkyMed.

Plasma Discharge

Topic: Space Plasma Discharge Transients from EMA3D

Presenter: Bryon Neufeld

Abstract: We demonstrate EMA3D’s ability to predict discharge transients from surface charging in a space plasma.  In our analysis, we obtain surface charging results in a space plasma environment and then evaluate discharge transients to cables and antennas.  We consider spacecraft-to-plasma, surface-to-surface, and spacecraft-to-spacecraft (rendezvous) discharges.  From a single geometric model, EMA3D allows the user to perform the entire space charging analysis, as well as seamlessly transition to other EMC simulations including lightning, HIRF, and conducted emissions.

 Webinar Video Recording:

Webinar PPT:

Lightning Class

HIGH INTENSITY RADIATED FIELDS (HIRF) COURSE

Electromagnetic Effects Compliance for Aircraft
HIRF/Lightning Design, Test Methods, and Regulatory Compliance

September 13-16, 2016

8:00AM – 5:00PM (T, W, TR)

8:00AM – 3:00PM (F)

National Institute for Aviation Research
Environmental Test Lab
3800 S. Oliver
Building 13L
Wichita, KS 67210

Fee:

  • $2,500 if registered before August 12, 2016
  • $2,750 if registered after August 12, 2016

Contact:
Andrew Nguyen
Email: environmental_lab@niar.wichita.edu
Phone: 978-5049

Register Here

About the course:
This comprehensive workshop will provide an awareness of all aspects HIRF and Lightning systems and aircraft testing in regard to compliance to the existing rules. In addition, with recent revisions to guidance material and FAA policy towards Fuel Tanks (25.981) and PED tolerance, it is critical that anyone working in this field be up to date on the developments.

For any questions about the class, feel free to Contact EMA

Topics include:

  • Background and Why HIRF is important?
  • The FAA/European requirements to demonstrate compliance – FAA/EASA Harmonized HIRF         and Lightning requirements
  • Equipment Qualification
  • Aircraft certification, modeling and testing (HIRF and IEL)
  • Pitfalls and problems
  • Design issues
  • Discussion of 25.981 Rule Revision Status
  • Using CEM Analysis to Support 25.981 Aircraft Certification Programs
  • Discussion on PED tolerance Policy

With emphasis on practical measurement and design guidance, this workshop is particularly relevant to engineers and technicians involved in aircraft HIRF and Lightning Clearance. As part of the practical presentations, the class will be providing demonstrations concerning critical aspects of the HIRF/IEL testing.

Presenters:

Billy Martin (NIAR: EME Lab Director: Regarded as one of the technical experts on HIRF and Lightning in the United States), Dave Walen (FAA’s Chief Scientific and Technical Advisor for HIRF, EMC and Lightning), Jeff Phillips (NIAR: Senior Research Engineer), Dr. Vignesh Rajamani, Ph.D. (Senior Associate, Technology Development Practice), Cody Weber (Senior Scientist at Electro Magnetic Applications, Inc.), Tim McDonald (Ph.D. Chief Scientist at Electro Magnetic Applications, Inc.).

Mesh Sensitivity

 

Finite Element Mesh Variation as Quality Assurance in Space Charging

EMA3D has tools which, when used in combination with Nascap-2K, provide the user a comprehensive and sophisticated space charging analysis framework.  One of the key capabilities that EMA3D provides is the ability to control the finite element mesh which serves as the basis for a Nascap-2K simulation object.

Control over the mesh within the EMA3D set of tools includes control over both the meshing algorithm and the mesh resolution.  Both of these aspects of the mesh are important to an analysis program.  Different mesh algorithms may represent different areas of the vehicle more accurately.  Some are stronger at maintaining the curvature of surfaces, while others are better at providing uniformity in the mesh gradient.

A finer mesh resolution generally provides more accurate results than a coarser mesh, however, a finer mesh takes longer to simulate.  In Nascap-2K the simulation time scales as the number of elements squared.  It is then desirable to find the coarsest mesh resolution which is still numerically accurate.

By using different simulation mesh algorithms and resolutions, the user can get a sense of the numerical accuracy and stability of their simulation results.  We present a flow chart that represents one possible strategy for using multiple meshes as the foundation of an accurate and stable simulation program:

 

1-mesh-algorithms-flow-chart

 

In this post, we flesh out some of the details of our flow chart and show how using multiple meshes can provide insight and confidence in the numerical accuracy of simulation results.

We show our simulation model in the figure below, where we have chosen three different mesh algorithms with roughly the same resolution to begin our sensitivity analysis with.  In the EMA3D/CADfix framework, the user starts with a geometrical model, assigns materials, and then meshes the geometry which gets directly exported as a Nascap-2K object.  The user can easily generate new meshes using a convenient mesh wizard.  New objects can be exported quickly, with the appropriate materials already assigned.

 

2-simulation-model-mesh-examles-for-nascap-nascap2k

 

Our model shown in the Figure is a simple model with just four materials: solar panels (cyan), elimstat paint (magenta), windows (blue) and FRSI thermal material (red).  The three different meshes are generated by three different algorithms that provide different combinations of curvature sensitivity and uniformity.

We simulate the model out to 10,000 seconds in a geosynchronous ‘worst case’ plasma.  We consider both a shaded (eclipse) environment and one in which there is illumination on the back side of the vehicle (away from windows and FRSI).

We start by looking at the results for the shaded scenario across these three algorithms.  We will look at sensitivity to the mesh resolution further down.  Our results are shown in the Figure below, where we plot the absolute maximum voltage to plasma on the vehicle minus the absolute minimum voltage to plasma on the vehicle, all scaled relative to the DELM mesh result.  By plotting in this way, we have an easy comparison across meshes for a relatively intuitive physical quantity.

When looking the plot, a couple of observations are in order.  First, the green curve corresponding to the DELC mesh (curvature sensitive mesh) shows a discrepancy relative to the other two meshes.  Second the green curve also appears to have some numerical fluctuations early in the simulation.  Taken together, our initial impression is that the DELC mesh is less accurate than the DELM and DELT meshes.  Our initial impression is also that these two meshes, DELM and DELT, are likely accurate since they are stable and agree with each other. However, in order to confirm these initial impressions, we look at the 3D plot of the voltage to plasma at the end of the simulation, which we show in the following Figure.

3-nascap-simulation-voltage-to-plasma-plot

4-3d-simulation-voltage-to-plasma-plot

 

The Figure shows a color representation of the induced voltages at the final moment of simulation.  We have included both the DELM and DELC meshes in the plot.  When looking at the 3D plot, we see that the DELC mesh has trouble capturing the spatial gradient on the solar arrays.  The results are choppy, especially compared to the smooth variation seen in the DELM mesh.  This confirms our initial impression that the DELC mesh results should be viewed with skepticism for this scenario.

We now consider a variation in the resolution of the mesh.  We have limited our analysis here to variations in the DELM mesh resolution.  The figure shows results in the same format as above for three different resolutions – labeled Fine, Medium and Coarse.  The number of mesh elements for each mesh is shown in the parenthesis next to the plot legend.

5-nascap-simulation-voltage-to-plasma-plot

When looking at variations in the mesh algorithm there is always some uncertainty as to which mesh should represent ‘baseline’.  However, when looking at variations in the mesh resolution, we can usually safely assume that the finer mesh is more reliable.  Looking at the results in the Figure we see that the Coarse mesh (776 elements) shows clear discrepancy with the Fine mesh (3622 elements), but that the Medium mesh (2050 elements) agrees relatively well with the Fine mesh.  In this case, the user may make a judgment based on the need for simulation speed versus the importance of numerical precision whether the Fine or Medium mesh is more suitable for their needs.  It is also possible that another mesh, perhaps with 2500 elements, would be a good compromise.

We now consider the results across the three algorithms for the scenario with illumination, which are shown in the Figure.  It is interesting to note in these results how much the DELC mesh results fluctuate relative to the other two meshes early in the simulation, but then they all converge toward later times.

6-nascap-simulation-voltage-to-plasma-plot

While it is reassuring to see consistency across the meshes in the ‘steady state’ of the results, the early fluctuations seen in the DELC mesh again indicate this mesh should be viewed with skepticism.  Although we have only plotted results relative to the DELM results as a ratio, the user can also plot the minimum and maximum voltages for each mesh separately.  Doing that would highlight clearly that the DELC mesh shows numerical instability at early times.

In this post, we have presented a strategy for using multiple meshes as the foundation of an accurate and stable space charging simulation program.  Our strategy takes advantage of the mesh and material capabilities present within the EMA3D/Nascap-2K interface.  Within this interface, the user can quickly generate simulation objects from different mesh algorithms and resolutions.  We have seen that numerical results can fluctuate between these different meshes and that by careful analysis the user can start to pinpoint which meshes are reliable and how fine a mesh resolution is required.  These capabilities help lay the groundwork for an accurate and reliable space charging analysis program.

Space Applications

Advanced Electromagnetic Modeling for Space Applications

 

Presentations a recent seminar and webinar can be found below.

Today electromagnetic (EM) modelling plays an essential role in the development of challenging projects in every engineering field.  This is especially true for space applications, where performances and design specifications have recently experienced an incredible increase in complexity.

This seminar will discuss the benefits of high fidelity EM modelling in standard applications such as antenna siting on satellites. Further, we will deal with non-conventional EMC (electromagnetic compatibility) problems such as the modelling of antennas mounted on re-entry vehicles in the presence of plasma cloud and analysis of the interaction of antennas with plasma plume emitted by ion thrusters.

This seminar is based on the experiences gained by IDS in more than 30 years as a consulting company participating in satellite programs such as  Sicral, Lisa pathfinder, SAC-D, Oceansat, Galileo, SmallGeo and Cosmo SkyMed.

Presenter: Dr. M. Bandinelli

Biography: M. Bandinelli received his degree in Electronic Engineering in 1986 from the University of Florence discussing thesis on numerical methods for antenna array design.

Since then he joined IDS S.p.A. where he was involved in the development of advanced numerical codes for electromagnetic modelling focused on antenna design and space application. Currently Mauro is the Director of the “ElectroMagnetic Engineering (EME) Division”.

His main area of interest includes:

  • Development of CAE tools design for electromagnetic applications;
  • Advances in numerical methods for electromagnetic modelling:
    • Full-wave techniques (Method of Moments, FEM, FDTD, MTL);
    • Hybrid techniques (MoM-GTD, MoM-FEM, MoM-MTL);
    • Asymptotic methods (GTD, PO, PTD);
  • Antenna siting design on naval, airborne, earthbound and spaceborne platforms (radiation patterns, link budgeting and EMI problems);
  • Antenna – plasma interaction;
  • Propagation analysis and antenna analysis applied to radar-TLC system analysis;
  • EMC analysis and design for electronic systems (for earth station, naval, avionic and

Bandinelli published about 100 original papers at international meetings and on technical journals, on topics related to his relevant experience.

Seminar Presentation

 

Webinar Presentation

Re-entry Antenna

Background and Motivation

Space vehicles re-entering the Earth atmosphere  become shrouded by a “dense” plasma (bow shock wave). The plasma frequency exceeds 1 GHz in most of “cloud” around the vehicle. Link obstruction occurs in most directions, causing the “blackout” of the link to ground stations.

The ESA Atmospheric Re-entry Demonstrator (ARD) program investigated experimentally the link to NASA TDRSS satellite. At the time, existing simulation teams found replicating the experimental results challenging. In this whitepaper, we describe the new modeling technique developed that correlates well with the experimental data. The technique considers diffraction around the plasma “cup” in order to accurately capture the effects.

ADF Re-entry Simulation Moduleadf-re-entry-simulation-models-particle-charging

With respect to space capsule re-entry antenna link for space vehicles, the communication black-out due t o the presence of plasma is one of the main challenges to overcome. The purpose of the ADF Re-entry simulation module is to provide all the means (input data interfaces, working procedures and modeling methods) necessary to analyze in depth this problem and support communication system and antenna design.

The steps include:

  • Define the flight trajectory ephemeris (latitude, longitude, altitude)
  • Define the ground station or data relay satellite location
  • Define the plasma cloud (available from existing spacecraft CFD models)

The outputs of the module include:adf-re-entry-simulation-models-particle-charging-graphs

  • Antenna gain pattern maps and polar/Cartesian plots
  • Induced structural currents
  • Channel transfer function for each station in the time or frequency domain, with the temporal evolution

Purchase the Software or Engage the EMA Services Team

The correlation achieved with the test results is dramatic. The tools are easy to use and fit into a streamlined workflow. Contact EMA today for this software module. Alternatively, our services team can perform this modeling or train internal staff on its use in a cost effective manner.

 

Charging Webinar

 

Topic:

Advanced CAE Tools for Spacecraft Charging Analysis with NASCAP-2K

 

Presenter:

Bryon Neufeld

 

Abstract:

EMA3D includes advanced CAE tools for spacecraft charging analysis with NASCAP-2K. These tools allow the user to import native CAD (in almost any format) directly into the EMA3D platform to serve as the basis for their surface charging simulation, ensuring a detailed and accurate model. The user may also develop their model manually using powerful geometry development capabilities. The EMA3D platform enables the user to define and assign NASCAP-2K materials directly to sections of the model. There is no need to assign materials element-by-element within the NASCAP-2K environment, thereby reducing development time. The user can also easily control the mesh from within the EMA3D platform, including changing the mesh resolution and mesh algorithm. Finally, space charging results can be parsed with EMA3D or further simulated using EMA3D’s tools to propagate discharges to cables or antennas. We provide an example of the process from beginning to end.

For any questions feel free to contact us.

 

Full Webinar Presentation and Video

 

 

Spacecraft Charging

Spacecraft Charging

EMA3D includes advanced CAE tools to extend NASCAP-2K and provide spacecraft charging analysis for plasma interaction and EMC characterization in space. Many US companies rely on NASCAP-2K, but find the CAD and CAE tools, such as meshes, to be cumbersome and underdeveloped.

EMA3D gives the ability to simplify, modify, and defeature geometry to prepare for NASCAP-2K simulation. The EMA3D tools can then be used to assign the plasma interaction material properties. Then advanced meshing creates a valid conformal BEM mesh that imports cleanly into NASCAP-2K. Finally, the results can be parsed with EMA3D or further simulated using EMA3D’s tools to propagate discharges to cables or antennas.

The following gives an example of the process.

Capsule CAD

The example below shows a spacecraft from a internet-available CAD download. As you can see, the model is not yet defeautured and is not appropriate for NASCAP modeling yet.

Capsule CAD from Internet fror NASCAP and NASCAP2K spacecraft particle charging simulation

 

Simplified, repaired and de-featured using EMA CADfix

The defeaturing is advanced, with automatic wizards and user-friendly tools.

Simplified, repaired and de-featured using EMA CADfix. Features are not included in NASCAP and NASCAP2K for spacecraft particle charging simulation
  • This capability is not included in standard NASCAP tools
  • Automated processing and defeaturing
  • Assign the material properties using sets that are easy to use

 

BEM Mesh in EMA CADfix

Next, you can create a BEM mesh that is high quality and captures all the important elements of the geometry.

BEM Mesh in EMA CADfix for NASCAP. High quality mesh with no errors and CAD traceability.
  • High quality mesh with no errors
  • CAD traceability

 

Opens Directly in NASCAP, with Materials Included

This allows the plasma engineer to take advantage of the good parts of NASCAP and omit the parts that are not advanced. The materials in this example are for illustration and are not realistic.

Opens Directly in NASCAP, with Materials Included. NASCAP CAE tools are outdated by 20 years and nearly unusable. However, The solver algorithm is compelling and useful.
  • NASCAP-2K CAE tools are outdated and not pleasant to use
  • The solver algorithm is compelling and useful

 

NASCAP Sample Results

One can view the results in NASCAP or export them to EMA3D. Further, more processing such as discharge coupling can be performed in EMA3D using the FDTD EM solver.

EMA3D FDTD Mesh

The EMA3D FDTD mesh of the same geometry is shown below. This is a general solver that can couple fields and waves as necessary to determine the threat to systems.

EMA3D FDTD Mesh. Use the results of NASCAP simulation to find the effects on the system. Couple discharges to antennas. Calculate total available energy from voltages. Non-linear breakdown modeling under development.
  • Use the results of NASCAP simulation to find the effects on the system
  • Couple discharges to antennas
  • Calculate total available energy from voltages
  • Non-linear breakdown modeling coming soon

Railroad Protection

EMA recently published a paper at the AREMA Railway Exchange conference in Minneapolis, MN entitled: “SYSTEM LEVEL FULL SCALE LIGHTNING TESTING OF PTC WAYSIDE C&S SYSTEMS.” A summary of the paper follows:

Positive Train Control requires a high degree of reliability and availability. In order to meet these requirements, CSX needed to ensure the lightning protection of its wayside installations. In order to verify the CSX lightning protection design, an extensive full scale test and validation of all lightning protection devices and their applications was accomplished.

The following items are discussed:

  • CSX Lightning Protection Approach
  • Summary of CSX PTC Lightning Protection Features
  • PTC Lightning Test Articles
  • Application of Numerical Simulations of Lightning Strikes to Wayside Signal Systems
  • Example Test Results
  • Summary of Results
  • Recommendations for Improvement

A PowerPoint presentation of this paper can be viewed at the bottom of this page.

INTRODUCTION

CSX’s implementation of Positive Train Control must ensure the reliability of wayside equipment.

A critical part of reliability is effective lightning protection. In order to verify the lightning protection approach, CSX performed extensive full scale testing of wayside PTC installations. This PTC system-level lightning test is the first of its kind in the railroad industry.

This test of two fully CSX configured PTC bungalows to threat level lightning is an innovative concept that provided a unique opportunity for verification of the CSX lightning protection approach that has been applied since 1998.

The test demonstrated the effectiveness of the protection approach, and also provided suggestions for future improvement.

CSX LIGHTNING PROTECTION TECHNICAL APPROACH

The Foundation of CSX Lightning Protection

In 1998, CSX decided that the foundation of its lightning protection approach must be consistent with the following objective:

     Eliminate Train Control service interruptions and signal equipment losses due to lightning related incidents.

This objective is consistent with that of other highly reliable systems in other industries for which there is no option for system failure. These include military command and control facilities, commercial aircraft, and other ground based critical systems.

Basis of Approach

The CSX protection approach is similar to that of other industries, and is based on the considerations of stress vs. strength.

In this case, stress is the incident lightning environment, which is quantified in terms of peak current, available energy, available charge, and current rate of rise.

Strength is a measure of the ability of the system to withstand the stress.

Stress and strength are compared to create the effectiveness of the protection approach. This effectiveness is stated in terms of the margin which equals the ration of strength/stress. For effective protection, the margin should be much larger than 1. If the stress is greater than strength, more protection is required.

Stress, the strength of the lightning environment, can be determined from several sources. First, field experience can be used to estimate the lightning levels that would be responsible to cause the observed damage. Second, Computational Electromagnetics can be used to perform numerical simulations of lightning strikes to wayside systems in order to characterize lightning currents that are incident on the wayside electronics and protection devices. Finally, the AREMA Signal Manual provides guidance in the lightning environment suitable for protection design.

SUMMARY OF CSX PTC LIGHTNING PROTECTION FEATURES

Basic Lightning Protection Rule

The basic rule of lightning protection is: Don’t allow lightning inside the bungalow!  The critical PTC electronics are inside the bungalow, so if lightning cannot penetrate the bungalow, then the electronics are safe.

In order to accomplish this, the following protection features are implemented:

  • Metal bungalow
  • Faraday cage
  • GE Tranquell AC arrester
  • RF coaxial in-line bulkhead arresters
  • Hybrid Low Voltage Arrester (HLVA) arrester for circuits having operating voltages less than about 30 volts
  • Grounding of spares and shields at both ends of cables

These are discussed in the following paragraphs.

Metal Bungalow

The metal skin provides an excellent shield upon which to apply protection for the lightning points of entry (POEs).

Figure 3.1 Aluminum house providing the basic barrier for lightning shielding of critical electronics

Aluminum house providing the basic barrier for lightning shielding of critical electronics

  • Aluminum house provides an excellent lightning shield

Faraday Cage

The cage is basically an extension of the bungalow surface inside the house, such that the house interior is a clean environment, and the interior of the Faraday cage contains the arresters and is the dirty external environment. Clean wires exit the cage with a very short lead length from the arrester, minimizing dirty environment coupling to the clean wires.

Figure 3.2 The CSX Faraday cage

The CSX Faraday cage

  • Isolates clean and dirty wires and the clean and dirty volume
  • House interior is a clean volume
  • Contains arrester with a short low inductance current path to the clean environment

GE Tranquell AC arrester

This is mounted in its own small metal box (another Faraday cage) and has nearly zero lead length for its arrester return paths. The surface area and small lead length of this arrester ensures a low impedance path that will minimize let-through voltages.

Figure 3.3 GE Tranquell AC power protection

GE Tranquell AC power protection

  • Nearly zero inductance ground plane connection
  • Small let-through voltage
  • Robust design

 

RF Coaxial In-Line Bulkhead Arrester

Below is an interior view of a bulkhead mounted RF coaxial cable arrester.

Figure 3.4 Interior view of bulkhead mounted RF coaxial cable arrester

Interior view of bulkhead mounted RF coaxial cable arrester

  • Bulkhead design keeps lightning currents outside the house
  • Provides coaxial cable center conductor transient protection
  • Maintains a clean interior volume

 

Hybrid Low Voltage Arrester (HLVA)

This is the HLVA that is used to protect low voltage circuits. It has the smallest let-through voltage of any arrester CSX has tested since 1998. It has never failed in a shorted mode in either extensive testing or in the field.

Figure 3.5 CSX Hybrid Low Voltage Arrester

CSX Hybrid Low Voltage Arrester

  • Non-shorting design
  • Requires no equalizers
  • Robust
  • Lowest let-through voltage
  • Visual fault indicators

Grounding of Spares and Shields

The image illustrates the grounding of shields and spares at both ends. The grounding is done within the dirty volume of the Faraday cage.

Figure 3.6 Grounding of shields and spares

Grounding of shields and spares

  • Grounded at both ends
  • Grounded within faraday cage dirty volume

 

PTC TEST OVERVIEW

There were 155 test shots with as much as 120 kA injected lightning current as follows:

  • Track circuits (Electrologixs) and arresters: 73 shots
  • Signal lamps (Electroblox and relay) : 31 shots
  • Communication and I/O cables between houses: 25 shots
  • AC power: 7 shots
  • RF links: 19 shots
    • Satcom: 10 shots
    • iNet: 5 shots
    • Cellular: 4 shots

PTC LIGHTNING TEST CONFIGURATION

The test articles consisted of two fully configured PTC bungalows as shown below. The internal equipment consisted of the following:

  • CNA 2000 Communications Network Adaptor
  • ElectroLogIXS VLC and EC5
  • ElectroBlox Standalone Wayside Interface Unit
  • MDS iNET 900 transceiver
  • A shielded six pair cable connection was also included from the A house to the B house, of which one pair was used.
  • A shielded 12 wire signal I/O cable also connects the A and B houses
  • Satellite connection with the iDirect Evolution 5 box via a satellite dish
  • Cellular connection via the Digi Transport WR44 box
  • RuggedCom RS930L switch
  • Battery chargers and batteries
  • Internal Faraday Cage containing arresters
  • House ventilation and lighting systems

CSX provides redundant IP communication paths into the PTC equipment enclosures as follows:

  • Local IP connection via telecom cable if available
  • Cellular connection
  • Satellite connection
  • A few remote locations may use a 220 MHZ radio to communicate to the locomotive directly instead of the IP connection back to the control center and to the 220 MHz base stations.
Figure 5.1 Two PTC bungalows for lightning testing

Two PTC bungalows for lightning testing

NUMERICAL SIMULATIONS OF LIGHTNING STRIKES TO WAYSIDE SYSTEMS

The PTC lightning test was supported with computational electromagnetic simulations of strikes to wayside installations. This provides a first principles estimate of the lightning current waveforms (i.e., the stress) incident on wayside systems to supplement AREMA waveforms.

Stress is a combination of the following attributes:

  • Peak current with units of amperes
  • Available energy: Action Integral = ∫i(t)2dt with units of Joules/ohm (also = A2-seconds)
  • Total charge: ∫i(t)dt with units of Coulombs

Lightning strikes to a typical CP location were numerically simulated with the software EMA3D from Electro Magnetic Applications (www.ema3d.com), which has been used on aerospace and military projects worldwide.

The incident lightning current is the standard 1% waveform commonly used for protection design of aircraft and ground stations.

The computational model is shown below. Four 200 kA lightning strikes were analyzed as follows:

  • Strike to Bungalow
  • Strike to Track
  • Strike to Ground
  • Strike to Signal Mast

The computed results included currents on track wires and signal wires. An example is shown below.  The largest lightning currents induced on track wires and signal lamp wires are as follows:

  • Track wires
    • Largest, for a strike to a rail
      • Amplitude: 95 kA
      • Action integral: 430 kJ/Ω
    • Second largest, for a strike to the bungalow or signal mast
      • Amplitude: 26 kA
      • Action integral: 55 kJ/Ω
    • Signal cable, for a strike to a signal mast
      • Amplitude: 170kA
      • Action integral: 1600 kJ/Ω
Figure 6.2 Wayside EMA3D computational model

Wayside EMA3D computational model

Figure 6.3 Example of computed current flow

Example of computed current flow

PTC TEST RESULTS SUMMARY

The results of the PTC test are summarized as follows:

  • No electronic units in the houses were damaged.
  • Momentary upsets were observed, all self recovered
    • Electrologixs: 30 sec recovery
    • iNet radio: momentary dropout, 30 sec recovery (closing the Faraday cage doors remedied this)
    • VDSL: momentary dropout: 30 sec recovery
  • AC Protection: GE Tranquell performed best of the arresters tested
  • HLVA was the best performing low voltage arrester
  • RF interfaces: all passed, but inconsistent behavior of Satcom arrester
  • Bonding of cable shields and spare wires to bungalow skin on both ends is a highly effective protection method
  • Faraday cage: highly effective
    • Clean/dirty isolation
    • Arrester ground lead short for minimum let-through

SUGGESTED DESIGN CHANGES

Several design changes were recommended as a result of this test: These included:

  • The Tranquell installation could be improved by using MOVs on only L1 and L2, and by connecting the neutral directly to bungalow skin ground.
  • Bulkhead arresters be added to the Satcom antenna design to eliminate lightning current penetration into the house.
  • The low voltage arresters on the signal lamp circuits could be eliminated

Full Conference Presentation

EMA Webinar

 

Topic:

Validation of Computational Electromagnetics Simulations to Support Aircraft Certification Projects for Direct and Indirect Effects of Lightning

 

Presenter:

Cody Weber

 

Abstract:

Computation Electromagnetic (CEM) simulations play an ever increasing role in the analysis and support for aircraft certification projects. CEM can be used to evaluate electromagnetic environmental effects as well as EMC/EMI system problems for design and certification support. This analysis can be used early in projects to investigate aircraft designs and assess the need for protections schemes but also to provide valuable results to aid in certification support. Both stages of simulation can provide significant program cost benefits by reducing program testing and developing a complete understanding of the EM response of a particular aircraft design. In this webinar, a senior EM scientist with more than a decade of CEM experience will highlight recent published efforts demonstrating the success of a large scale CEM simulation validation effort for direct and indirect effects of lightning on a commercial aircraft program with a composite fuel tank. The webinar will cover the validation comparisons of experiment and simulation results for a sample wingbox and a full aircraft. It will also cover some critical aspects of modeling and simulation required to achieve good correlations with experimental results.

For any questions about the webinar, please contact us.
 

Full Webinar Video and Presentation